Impedance of PL-259 and "Barrel" connector?
Scott McClements
determined by the distance of the inner conductor to the outer
conductor. So, what is the impedance of the PL-259 and the "Barrel"
connector (whatever the number is on that thing)? Are they suppose to
have a characteristic impedance of 50 ohms? Something to ponder at 12:52
am.
Scott.
R E Heath
The PL-259 and other connectors of the "UHF" series are non-constant
impedance connectors. The resulting mismatch is of negligible
significance at the lower HF frequencies and they are even usable in
many circumstances up to about 150 MHz. The manufacturers use them for
the simplest reason -- they are CHEAP! I replace "UHF" connectors
whenever conveniently possible with N, TNC or BNC connectors and always
buy equipment with N connectors if there is the choice.
Bob, W8BZ, VA3BZ
Dick Carroll
I spent a number of years working with UHF gear in the 450-470 mhz
region that all used UHF/PL259-SO239 style connectors of good quality,
installed at the General Electric factory. Never had a hint of a problem
from it and all equipment operated at rated output power an receiver
sensitivity. The impedence bump introduced by the connectors is
completely tolerable through 500mHz.
Dick
Dale Parfitt
Scott McClements wrote:
Depends on the type of dielectric- and because the transition is not a
smooth one, it varies. Pretty much a don't care situation up through 70cM.
Dale W4OP
Ian White, G3SEK
That's almost true, except for one word: "completely". It isn't quite
that clear-cut.
The impedance bump from a single 'UHF' connector is almost always
tolerable through 500MHz, except in special circumstances like test
equipment.
It becomes less tolerable if there are several of these connectors at
various places along a transmission line, causing reflections at a
variety of phase angles due to the lengths of the line segments.
Murphy's Law says that those small, "completely tolerable" reflections
are going to add rather than cancel. For example, you may find that the
SWR has crept up to around 2, which will start to activate the SWR
shutdown on some transmitters. This can be very difficult to trouble-
shoot, because every line segment will test out OK. Since the only thing
left untested is the antenna, the next thing is to climb the tower...
only to discover there's nothing wrong up there either. Changing to
constant impedance connectors such as N and BNC can be a complete cure.
Unfortunately N and BNC fall short in power handling at UHF. BNC drops
out of the race because it will only accept small cables which get hot,
soften and break down. N connectors are limited by the small center pin
and the possibilities for misalignment. Above 1kW on 432MHz, they are
right on the edge - if they're not absolutely perfect, you find out very
quickly! On the other hand, 'UHF' connectors are reported to be good for
many kW up to at least 50MHz.
73 from Ian G3SEK Editor, 'The VHF/UHF DX Book'
'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.com/g3sek
Wes Stewart
wrote:
>>
>>R E Heath wrote:
[snip]
>> I spent a number of years working with UHF gear in the 450-470 mhz
>>region that all used UHF/PL259-SO239 style connectors of good quality,
>>installed at the General Electric factory. Never had a hint of a problem
>>from it and all equipment operated at rated output power an receiver
>>sensitivity. The impedence bump introduced by the connectors is
>>completely tolerable through 500mHz.
>
>That's almost true, except for one word: "completely". It isn't quite
>that clear-cut.
>
>The impedance bump from a single 'UHF' connector is almost always
>tolerable through 500MHz, except in special circumstances like test
>equipment.
>
>It becomes less tolerable if there are several of these connectors at
>various places along a transmission line, causing reflections at a
>variety of phase angles due to the lengths of the line segments.
>Murphy's Law says that those small, "completely tolerable" reflections
>are going to add rather than cancel. For example, you may find that the
>SWR has crept up to around 2, which will start to activate the SWR
>shutdown on some transmitters. This can be very difficult to trouble-
>shoot, because every line segment will test out OK. Since the only thing
>left untested is the antenna, the next thing is to climb the tower...
>only to discover there's nothing wrong up there either. Changing to
>constant impedance connectors such as N and BNC can be a complete cure.
Ian brings up a good point. Microwave designers are especially worried about
this because the phase angle is rotating so quickly that even just two
reflections separated by a short distance can cause wild VSWR ripple as the
frequency is swept. Add a couple of more reflections by inserting another
device in a cascade and you quickly have a mess.
The worst case VSWR (all reflections in phase) is the product of the individual
VSWRs. So even at VHF, there can be a problem, if for instance, you have a
system with an SWR bridge or power meter in the line, followed by a filter,
followed by a change-over relay.....
If each of these has a "UHF" connector or two with a 1.2:1 VSWR or worse, and
the cable lengths happen to be "wrong", you may have a problem.
>
>Unfortunately N and BNC fall short in power handling at UHF. BNC drops
>out of the race because it will only accept small cables which get hot,
>soften and break down. N connectors are limited by the small center pin
>and the possibilities for misalignment. Above 1kW on 432MHz, they are
>right on the edge - if they're not absolutely perfect, you find out very
>quickly! On the other hand, 'UHF' connectors are reported to be good for
>many kW up to at least 50MHz.
The key is proper alignment and pin depth setting. I once tested a couple of
dozen cables for power handling capability at 10 GHz. These were flexible
cables using SMA connectors and were for a space application. The requirements
were 100W input with a 3:1 VSWR load for one hour at an ambient temperature of
90 deg. C. All of the cables survived without degradation.
What was remarkable was that to achieve the 3:1 VSWR load I used a length of
0.141" semi-rigid coax, with an SMA connector on one end and a short on the
other. The majority of the length was coiled up and placed into a can of water
outside the temperature chamber for cooling. The SMA connecter on this cable
survived about thirty hours of abuse as did the isolator in the Watkins-Johnson
400 W TWTA.
Something to not be overlooked when using UHF connectors is the ghastly assembly
problem. It is easy to melt the dielectric when soldering the braid, to the
point that the power handling capability is reduced.
Wes N7WS
Bill Turner
>The PL-259 and other connectors of the "UHF" series are non-constant
>impedance connectors. The resulting mismatch is of negligible
>significance at the lower HF frequencies and they are even usable in
>many circumstances up to about 150 MHz. The manufacturers use them for
>the simplest reason -- they are CHEAP! I replace "UHF" connectors
>whenever conveniently possible with N, TNC or BNC connectors and always
>buy equipment with N connectors if there is the choice.
_____________________________________________________________
This subject comes up periodically and there are always differing opinions. The
N, TNC and BNC connectors have their advantages, but they have one disadvantage
too - they are mechanically weaker than the PL-259 type and have a lower power
rating, especially at VHF. The N connector in particular has an annoying
habit of having the center conductor pull out of it's mate at a most inopportune
time. I understand there are versions available which do a better job of
locking it in place, so be sure to get one of those if you think that's a
concern.
PL-259s work fine for most applications and the low cost, simplicity and
universality of them is good enough for me and lots of other folks.
w7ti
Pie®©
What about systems with 75 Ohms impedance that use BNC connectors?
Are these the same 52 Ohms connectors we use for our purposes, or are
different
ones?
Thanks & 73' de IK2VTJ, Piero.
Merry Christmas & Happy new Year to everybody.
http://www.infinito.it/utenti/ardf.it
http://ardfitalia.supereva.it
http://www.qsl.net/ik2vtj
Dale Parfitt
"Pie®©" wrote:
> What about systems with 75 Ohms impedance that use BNC connectors?
> Are these the same 52 Ohms connectors we use for our purposes, or are
> different
> ones?
> Thanks & 73' de IK2VTJ, Piero.
75 Ohm systems would purchase 75 Ohm BNC connectors- same with type N 75
Ohms.
Dale W4OP
Tom W8JI
Scott,
Like many things in life, the real problem is with the female.
The male end of the UHF connector set is almost perfect. There is no
bump there.
At the female-end, a simple typical SO-239 has an impedance of 30 to
40 ohms. However, that "bump" is only 1/2 inch long, so it will NOT
caude a problem unless you have a lot of them spaced the wrong
distance apart at frequencies below 150 MHz or so.
Even at 450 MHz, the effect is often minor.
The pro's outweight the con's in my book, since a conventional good
quality UHF connector set will handle much higher line SWR and power
than a N connector. A regular UHF connector is much easier to assemble
also.
N connectors are fine below 1500 watts with low SWR, and constant
impedance connectors are needed for critical measurements or UHF and
higher work, but they are not needed below 200 MHz or so in almost any
application.
Barrel connectors are a slightly worse problem since the length is
longer. The general rule is if you keep the length of slight impedance
bumps below 1 electrical degree, they won't bother almost anything you
ever do.
That means on 160 meters you could have 1.5 FEET of total connector
"bump" area before before you could measure any difference. On six
meters, that would be only one connector....but remember this is the
WORSE situation where you could normally measure any change at all.
73 Tom
Ian Jackson
<GTE/par...@GTE.net> writes
Yes, there are both 50 ohm and 75 ohm BNC connectors.
However, the main difference is not the diameter of the inner conductors
(essentially identical). It is the amount of dielectric which is
present. 50 ohm has more than 75 ohm.
Mechanically, 50 and 75 ohm connectors are totally 'inter-connectable'.
Also, electrically, I doubt if you will see any difference in amateur
use.
Also, the 'inner parts' of 50 ohm BNC and N connectors are essentially
identical. You can make an electrical connection between a male N and a
female BNC.
IMPORTANT NOTE #1: This is NOT true for 75 ohm N-connectors. The
diameters of the inner conductors of 75 ohm N-connectors are MUCH less
than for 50 ohms. You can NOT connect a male 75 ohm N to ANY BNC or N
female (the inner conductor simply does not make contact).
IMPORTANT NOTE #2: NEVER, NEVER connect a 50 ohm male N to a 75 ohm
female N. You will end up with a SERIOUSLY damaged female. If I had my
way, this would deserve capital punishment for a second offence!!!
73,
Ian.
Richard Clark
<ianja...@g3ohx.demon.co.uk> wrote:
>
>IMPORTANT NOTE #2: NEVER, NEVER connect a 50 ohm male N to a 75 ohm
>female N. You will end up with a SERIOUSLY damaged female. If I had my
>way, this would deserve capital punishment for a second offence!!!
>
>73,
>Ian.
>
Hi Ian,
I've also observed this to be a problem with HV BNC connectors
connecting into standard BNC sockets. Here the problem is with
length.
73's
Richard Clark, KB7QHC
Roy Lewallen
BNC connectors have the same pin sizes. The different impedance is
effected by removing some dielectric around the center pin in the 75 ohm
version rather than changing the pin diameter. So they'll mate without
damage. I don't recall where I saw this, but think it was in some
literature from a connector manufacturer, and it sounded like this is
standard for BNCs. Is this true only for BNC and not for N connectors?
Or do only some manufacturers do it this way?
Roy Lewallen, W7EL
Ian White, G3SEK
Since the inner on those MHV connectors mates before the outer shield,
the punishment could indeed be capital.
Ian White, G3SEK
>I recently came across some information indicating that 50 and 75 ohm
>BNC connectors have the same pin sizes. The different impedance is
>effected by removing some dielectric around the center pin in the 75 ohm
>version rather than changing the pin diameter. So they'll mate without
>damage. I don't recall where I saw this, but think it was in some
>literature from a connector manufacturer, and it sounded like this is
>standard for BNCs. Is this true only for BNC and not for N connectors?
>Or do only some manufacturers do it this way?
The pin diameter is the same, in the parallel-sided part, but the end
tends to be more pointed in the 75 ohm plugs. This means that a
perfectly assembled 75 ohm plug may not mate reliably with a 50 ohm
socket. With typical off-center amateur assembly, there's no problem.
>Richard Clark wrote:
>>
>> On Sat, 16 Dec 2000 22:05:37 +0000, Ian Jackson
>> <ianja...@g3ohx.demon.co.uk> wrote:
>>
>> >
>> >IMPORTANT NOTE #2: NEVER, NEVER connect a 50 ohm male N to a 75 ohm
>> >female N. You will end up with a SERIOUSLY damaged female. If I had my
>> >way, this would deserve capital punishment for a second offence!!!
>> >
>> >73,
>> >Ian.
>> >
>>
>> Hi Ian,
>>
>> I've also observed this to be a problem with HV BNC connectors
>> connecting into standard BNC sockets. Here the problem is with
>> length.
The MHV connector is an accident waiting to happen. Not only is it
designed so that it can be forced into a BNC socket, but also the HV
center pin mates before the grounding shield. The SHV connector is far
safer because it cannot mate with anything else, both center pins are
deeply recessed and the shield connects first.
Richard Clark
<G3...@ifwtech.com> wrote:
>The MHV connector is an accident waiting to happen. Not only is it
>designed so that it can be forced into a BNC socket, but also the HV
>center pin mates before the grounding shield.
Hi Ian,
In the Navy, we used to call these suicide adapters. Another risk was
found at our RTTY patch panels that used phone plugs to carry the
juice in the loop. Which end to disconnect first?
Neither could hold a candle to the AC Mains to aligator clip leads we
called the KillsMeQuick.
rsm...@home.com
>Like many things in life, the real problem is with the female.
>The male end of the UHF connector set is almost perfect. There is no bump
>there.
>At the female-end, a simple typical SO-239 has an impedance of 30 to 40
>ohms. However, that "bump" is only 1/2 inch long, so it will NOT caude a
>problem unless you have a lot of them spaced the wrong distance apart at
>frequencies below 150 MHz or so.
>Even at 450 MHz, the effect is often minor.
>The pro's outweight the con's in my book, since a conventional good
>quality UHF connector set will handle much higher line SWR and power than
>a N connector. A regular UHF connector is much easier to assemble also.
>N connectors are fine below 1500 watts with low SWR, and constant
>impedance connectors are needed for critical measurements or UHF and
>higher work, but they are not needed below 200 MHz or so in almost any
>application.
>Barrel connectors are a slightly worse problem since the length is
>longer. The general rule is if you keep the length of slight impedance
>bumps below 1 electrical degree, they won't bother almost anything you
>ever do.
>That means on 160 meters you could have 1.5 FEET of total connector
>"bump" area before before you could measure any difference. On six
>meters, that would be only one connector....but remember this is the
>WORSE situation where you could normally measure any change at all.
It also depends on what you mean by "barrel" connectors. I have known both
the short uhf female to uhf female connectors and the uhf female-uhf
female bulkhead connectors described this way. (The bulkhead connectors
are about 2 inches long (5cm) whereas the others are about 3/4 of an inch
(2 cm) long. The bulkhead connectors have horrible effects even at VHF
frequencies and shouldn't ever be used for anything above 30 MHz in my
view.
Bob, VE7HS
Speak softly and carry a cellular phone.
--
-----------------------------------------------------------
rsm...@home.com
-----------------------------------------------------------
Bill Aycock
seen longer. They are used to go through walls and window frames, as
well as bulkheads. I wonder at your statement of 'horrible effects'.
Have you had direct experience with them at ham frequencies such as 50
and 144 mHz? What level of attenuation did they cause?
This is not an idle question. I currently have a 3" barrel feeding the
line for a tri-bander through a window frame, and am about to add one
for a 6M yagi. It, and a 2M line now run through 1" PVC.
Bill-W4BSG
David J. Windisch
Neither could hold a candle to the AC Mains to aligator clip leads we
called the KillsMeQuick.
73's
Richard Clark, KB7QHC
That's (more properly) a 'suicide cord'.
--
73, Dave, K3BHJ
Peter O. Brackett
In the British/Commonwealth Navys the "mains" were [maybe still are] DC, but
the same name applied "kills me quick".
The Navy radio/crypto room RTTY patch panels carrying the 60ma loops often
had very high voltages behind them, we just didn't hlod the phone jacks in
our mouths while making patches, heh, heh.
Peter K1PO [ex RCN electrician's mate]
"Richard Clark" <rwc...@rwclark.seanet.com> wrote in message
news:igw8Oq2Cy6D7QZP6=fcb60...@4ax.com...
Jynx
>
>N connectors are fine below 1500 watts with low SWR, and constant
>impedance connectors are needed for critical measurements or UHF and
>higher work, but they are not needed below 200 MHz or so in almost any
>application.
What they *do* give you (when properly prepared) is far
better weather-proofedness than 'UHF' connectors.
Knowing that's what I have at the top of my tower helps me sleep a
little better at night.
Jonesy
--
Marvin L Jones | jonz | W3DHJ | OS/2
Gunnison, Colorado | @ | Jonesy | linux __
7,703' -- 2,345m | frontier.net | DM68mn SK
tom_b...@agilent.com
the male or the female, unmated, will cause a rather large reflection!
But in the mated pair, I've seen impedances as low as about 25 ohms,
maybe a bit lower, and the 40-ohm end of the range is mighty rare in
those I've looked at.
If you do have a UHF mated pair that's 25 ohms for, say, 1 inch length,
and if the velocity factor is 0.5 (typical insulation in UHF connectors
has a higher dielectric constant than polyethylene, though you can get
Teflon ones that are better: electrically shorter and also higher
impedance), at 450MHz, that's about 27 electrical degrees. That will
transform 1:1 SWR into very nearly 2:1. Even half an inch, about 14
electrical degrees, gets you to about 1.42:1. If you have a couple of
the 25-ohm 1" mated pairs as above on 450MHz, with about 160 electrical
degrees of coax between them, you get to over 2:1 SWR. That assumes low
(0.01dB) loss in the connectors and in the interconnecting coax; higher
loss line reduces SWR of course. But on a 440 transmitter with one
single run of line between it and its antenna, it's quite possible to
design for very low loss and low SWR using UHF connectors: the
transmitter can be designed to deliver power to the impedance seen
looking into the UHF connector on the transmitter, from the inside, when
it's terminated into 50 ohms, even though that's not 50 ohms and in fact
is somewhat reactive...and at the antenna end, the antenna can be tuned
to present a 50 ohm match to the PL-259-terminated transmission line.
So at each end, the UHF can be accounted for, with practically no ill
effects. And at each end, the socket--which I'll agree is the
controlling factor for most of the "bump"--is under the control of the
designer of the equipment. In summary, the effect can be bad if
unaccounted for, but can be pretty small if accounted for.
I'm trying to understand if the N connectors I'm familiar with are the
same N connectors that others here are talking about. They won't take
as much kicking around in the dirt as a UHF plug, but I haven't notices
problems with pins pulling out...that seems like a defective connector
design.
A note on between-series matings: if it was an emergency, I'd plug an N
into a BNC, but since the N pin is distinctly larger diameter, I feel
this is a really bad practice. I think there's a very significant
chance of springing the BNC and then not having it mate properly with
it's own type.
Cheers,
Tom
In article <3a3bd7a1...@news.akorn.net>,
--
Tom Bruhns -- K7ITM
Sent via Deja.com
http://www.deja.com/
Ian White, G3SEK
>
>I'm trying to understand if the N connectors I'm familiar with are the
>same N connectors that others here are talking about. They won't take
>as much kicking around in the dirt as a UHF plug, but I haven't notices
>problems with pins pulling out...that seems like a defective connector
>design.
>
positive location for the center pin, which can be assembled either
"long" or "short" according to exactly how the coax is trimmed and the
pin soldered on. With semi-airspaced cables that don't have a positive
grip on the centre conductor, that conductor can move as the cable
settles into place, and the connector does nothing to stop it. I've seen
the pin spring out as much as 1/16-in when the plug is unscrewed, and
the center contacts in N sockets badly splayed out as a result.
Also the MIL-pattern connector has a poorly designed cable clamp because
all the force is taken on the braid, right where it comes out of the
cable. That's also all the electrical contact to the braid. The water
seal (a cut-one-time rubber washer) has very little mechanical pressure
to make it work. All the above design flaws are present in the MIL-
pattern BNC as well.
The other, more modern, design is called the "pressure sleeve" type.
That has a locating ring on the center pin which resists endways
movement, and helps compensate for amateur cable trimming. It also has a
ferrule arrangement which contacts a large area of braid, and a big
rubber sleeve that both clamps the braid very firmly and seals against
water. When the rear nut of a pressure sleeve N connector is fully
tightened, you can swing on the RG-213 but it won't pull out (on the
BNC, the RG-58 will tear apart but the pressure sleeve clamp won't let
go).
The pressure sleeve pattern are so much better, I won't even let anyone
*give* me the other type any more.
Coming back to the PL-259, pressure sleeve versions of that plug are
also available, which avoid all the usual problems of soldering the
braid. M/A-COM make one, but I have no idea who distributes it in the
USA.
A lower-cost nickel plated version is available in the UK as Farnell
part number 724816 (for RG213) or 724804 (for RG58). See
www.farnell.com/uk/ and search for either part number (no pictures
unfortunately).
Tom W8JI
>On Sat, 16 Dec 2000 21:10:15 GMT, Tom W8JI scribbled:
>>
>>N connectors are fine below 1500 watts with low SWR, and constant
>>impedance connectors are needed for critical measurements or UHF and
>>higher work, but they are not needed below 200 MHz or so in almost any
>>application.
>
>What they *do* give you (when properly prepared) is far
>better weather-proofedness than 'UHF' connectors.
>Knowing that's what I have at the top of my tower helps me sleep a
>little better at night.
>
>Jonesy
Since N connectors fail at much lower power for a given SWR, and since
I know how to weather-proof a connector (which N connectors need
also), I use UHF connectors in everything except my low power UHF
applications.
I also like them because they are easier to install, and stronger if
the cable has any mechanical strain.
73 Tom
Tom W8JI
>Seems to me it's pretty hard to blame it on the female end. Either
>the male or the female, unmated, will cause a rather large reflection!
>But in the mated pair, I've seen impedances as low as about 25 ohms,
>maybe a bit lower, and the 40-ohm end of the range is mighty rare in
>those I've looked at.
Better look again Tom. Inside the PL-259 the cable dimensions are
exactly the same as the cable you have installed. That's true right up
to the start of the pin.
The entire problem is in the female connector, were at the mating
female section it is a larger dimension. Zo there is typically in the
30-35 ohm range, but if the dielectric is removed (some connectors
have a mostly air dielectric) impedance moves up close to 50 ohms.
>If you do have a UHF mated pair that's 25 ohms for, say, 1 inch length,
>and if the velocity factor is 0.5 (typical insulation in UHF connectors
The only way you'd have a bump one inch long of 25 ohms with a Vp of
5 is if you had an absolute junk barrel connector at that point.
>has a higher dielectric constant than polyethylene, though you can get
>Teflon ones that are better: electrically shorter and also higher
>impedance), at 450MHz, that's about 27 electrical degrees. That will
>transform 1:1 SWR into very nearly 2:1. Even half an inch, about 14
>electrical degrees, gets you to about 1.42:1. If you have a couple of
>the 25-ohm 1" mated pairs as above on 450MHz, with about 160 electrical
>degrees of coax between them, you get to over 2:1 SWR. That assumes low
>(0.01dB) loss in the connectors and in the interconnecting coax; higher
>loss line reduces SWR of course. But on a 440 transmitter with one
>single run of line between it and its antenna, it's quite possible to
>design for very low loss and low SWR using UHF connectors: the
>transmitter can be designed to deliver power to the impedance seen
>looking into the UHF connector on the transmitter, from the inside, when
>it's terminated into 50 ohms, even though that's not 50 ohms and in fact
>is somewhat reactive...and at the antenna end, the antenna can be tuned
>to present a 50 ohm match to the PL-259-terminated transmission line.
>So at each end, the UHF can be accounted for, with practically no ill
>effects. And at each end, the socket--which I'll agree is the
>controlling factor for most of the "bump"--is under the control of the
>designer of the equipment. In summary, the effect can be bad if
>unaccounted for, but can be pretty small if accounted for.
No one I know of recommends UHF connectors for 450 Mz, because if you
use enough connectors and they are spaced the "wrong distance" apart
you can indeed cause SWR problems at UHF. Actually with enough
connectors spaced the the wrong distance apart, it can cause a SWR
problem at 30 MHz, but then a line with 25 or more female connectors
probably needs to be redesigned anyway.
>I'm trying to understand if the N connectors I'm familiar with are the
>same N connectors that others here are talking about. They won't take
>as much kicking around in the dirt as a UHF plug, but I haven't notices
>problems with pins pulling out...that seems like a defective connector
>design.
The center pins pull back because of how the N grabs the cable.
Nothing secures the center pin in most N connectors.
If you use the N with "superflex" cables (in some cables the jacket
does not grip the braid and outside of the inner dielectric securely)
the cable can "pull back" the center pin on the ends. You have to be
very careful what type of coax you use with an N connector, which is
what you'd want to do at UHF frequencies anyway.
Using an N connector at VHF and lower is almost silly, since there is
nothing to be gained except headaches. The exception is if you are
making precision measurements.
73 Tom
Tom W8JI
<G3...@ifwtech.com> wrote:
>The pressure sleeve pattern are so much better, I won't even let anyone
>*give* me the other type any more.
>
>Coming back to the PL-259, pressure sleeve versions of that plug are
>also available, which avoid all the usual problems of soldering the
>braid. M/A-COM make one, but I have no idea who distributes it in the
>USA.
Even if you are so clumsy that you melt the dielectric, it has no
where to go and the center conductor can't migate. An exception might
occur in foamed cables that are being flexed or bent at the connector.
If people soldered properly, they wouldn't have problems soldering the
braid. Most of those problems are because they do not file the
connector near the holes and pre-tin the connector with a light layer
of solder BEFORE attaching it to the coaxial cable.
A secondary issue is they use a small soldering iron, and don't have a
wet rag available for cooling the connector during or after soldering.
If you heat each hole with a high wattage gun or iron, while the
connector is laying on a wet surface, you can solder all you like
without "melting through" the 1/4 inch thick insulation.
73 Tom
Peter Bertini
"> > Tom W8JI" <2w...@contesting.com> wrote in message
news:3a3f7db4...@news.akorn.net...
> On Tue, 19 Dec 2000 07:49:44 +0000, "Ian White, G3SEK"
> <
Snip
> A secondary issue is they use a small soldering iron, and don't have a
> wet rag available for cooling the connector during or after soldering.
> If you heat each hole with a high wattage gun or iron, while the
> connector is laying on a wet surface, you can solder all you like
> without "melting through" the 1/4 inch thick insulation.
>
> 73 Tom
Tom
I also find using quality silver plated connectors with teflon insulators to
be a big
plus for ease of soldering. I've thrown away more cheap UHF males than I've
used
over the years.
Pete
Bill Turner
>and don't have a
>wet rag available for cooling the connector during or after soldering.
______________________________________________________________
Excellent idea. Nothing in the universe takes longer to cool down than a
just-soldered PL-259.
w7ti
Ian White, G3SEK
Ain't no denying none of the above. There's nothing wrong with the
conventional PL-259 if you have a big iron and know how to use it.
The only problem is the number of people who either don't know how to do
it or don't have the necessary soldering iron. Number me in the second
group... and for outdoors winter soldering, better make that a *monster*
iron. I reckon I can buy a lot of pressure sleeve PL-259s for the price
of an iron that can really handle the conventional type.
David
Well just my 2 cents, I would use a N style connector where ever possible!
The PL-259 is a bit lossy .25-.50 db loss depending how you install & solider.
A RCA connector has better loss properties than a PL-259 hi hi.
Just my 2 cents...sk
--
73 de David--kb9lpk <><
The Box said "Win95,Win98,NT40 Win2000 or better" So I installed Linux
email- kb9...@telocity.com
Ham email- kb9...@kb9lpk.ampr.org
Homepage- http://members.telocity.com/kb9lpk
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My Equipment Sale page is http://64.193.106.97/sale.html
Shop at our wonderful gift shop on the web! http://www.giftsheavensent.com
David
Wet rag potential problem there!
Well this can also cause cold solider contact in most cases. The proper
use of high wattage irons and contact time is really not much different
than any welding principles. Ya get it to hot or just right practice practice
practice. Hey and what is better way to cool than to apply a heat sink ie
forcipes ect. Not a wet rag its to fast of a cool and bad solder conductivity
(cold solider joint) can certainly result!
If you get it hot enough not to dissipate heat fast ie; 1 minute or less
you are not properly applying heat. Also I found that the silver teflon
PL-259 are most conducive not to mention heat dissipation!
Bill Aycock
RCA connector comparative performance?
An inquisitive mind wants to know- Bill-W4BSG
Ralph Mowery
this info up on the losses..
K1TTT Technical Reference
Quick Reference | Whats New | K1TTT Home | Tech Reference
From: k7...@ncw.net (Gary Nieborsky)
Subject: Re: Cable Attenuation Question
Back in senior year at Washington State U (W7YH, Go Cougs!) we had to do a
measurement project in Measurements Lab. Since there were two hams in the
Lab we decided to measure losses in coax connectors (the Prof was a ham
too). We set up a calorimeter and measured I**2R losses from DC to 2 GHz
for a PL259/SO239 combo (did it for BNC and N too...hey it was a senior
project).
Here are some of the results from my Lab Notes:
Input power = 1,000 watts (100V, 10A @ DC, homebrew 4-1000 .1-30 MHz,
borrowed USAF signal source 30-2,000 MHz (black box from Fairchild AFB),
Bird dummy load)
(We used a kW because neither of us had ever run more than 100 watts...power
trip!)
f (MHz) Loss (W) dB
0.1 1 -0.00435
1 1.2 -0.00521
10 1.3 -0.00565
20 1.5 -0.00652
30 1.8 -0.00782
50 2.2 -0.00957
100 2.6 -0.01131
200 3.5 -0.01523
300 5 -0.02177
400 7 -0.03051
500 10 -0.04365
1000 15 -0.06564
1250 18 -0.07889
1500 28 -0.12334
1750 39 -0.17277**
2000 100 -0.45757**
** Connector failed before calorimeter stabilized.
We attributed the steep upswing after 100MHz to the finish on the connector,
not the connector design. Nickel plating seems to exhibit non-linearity
above 100MHz. The N and BNC runs were much better. BNC went flakey above
600MHZ (RG-58 size, RG-8 BNC went to 1000 MHz). We were able to isolate
cable loss from connector loss by building a teflon box around the connector
body and only "viewing" the inside of the box with the sensor. The
Department Chair was not at all happy that this teflon box cost $750 to
build (teflon was rare in 1977).
As you can see from the table we experienced two failures. Both were due to
the solder melting in the probe part of the connector. The 1250 and 1500
watt runs showed discoloration but no melting. The values for 1750 and 2000
MHz were the calculated values at the time of failure. Each run took 1
hour, these two failed 28 and 17 minutes into the test.
We experienced a failure of an N connector at 2000MHz. We ran the output
up in 100 watt steps until we observed a sharp up turn in losses. We were
able to boil the water in the calorimeter at 15,000 watts and at 17,100
watts the fingers inside the connector relaxed and started arcing.
Before this experiment I was paranoid about my connectors. Since then I
have only been concerned with the quality of the assembly and water ingress.
My take on it.......
73 Gary K7FR
At 02:25 PM 9/15/96 -0400, you wrote:
>In a message dated 96-09-14 19:24:27 EDT, you write:
>
>>loss with the formula dB = 10(log PO/PI). Record this value as a
reference
>>so that some day when the cable is down and about to go up again you can
see
>>if the cable is still as good as when you bought it. (allow .1 dB for the
>>connectors at each end or .2 dB total).
>
>Hi,
>
>I keep seeing this thing about connector loss everywhere I look. It's
become
>accepted as fact in our community, but it's folklore. Here's an example
>why....
>
>With .1 dB loss per connector, power loss in a PL-259 SO-239 combo would be
>about 35 watts at 1500 watts. Loss is concentrated in the center pin and
>dielectric of the SO-239 section, in an area less than one half inch long.
>The PL-259 section has almost no loss or impedance bump when properly
>installed.
>
>35 watts of connector heat (with a 1500 watt transmitter), when
concentrated
>in the inside of the SO-239, would quickly make the connector so hot it
would
>be untouchable. In a few minutes melt the solder connection and dielectric.
>If you doubt this, turn on a 35 watt lamp for a few minutes and touch the
>glass. Now imagine how hot the galss woud be if it was all within a quarter
>inch of the filament.
>
>At 30 MHz, the loss of a 239-259 combo is totally unimportant. One foot of
>9913 cable has much more loss.
>
>73 Tom
>
>
---------------------------------------------------------------------------
David Robbins, K1TTT k1...@berkshire.net
"David" <kb9...@telocity.com> wrote in message
news:3A4010E8...@telocity.com...
John D. Farr
the outer diameter of the center conductor to that of the inner diameter of
the shield rather than a specific distance. I've seen 4 inch coaxial line
with a 50 ohm impedance and the distance between the conductor and the
shield was much much greater than that of RG58. Characteristic impedance is
also a function of the dielectric constant of the material between the
center conductor and shield.
John.
KC4ZXX
"Scott McClements" <yet...@grove.iup.edu> wrote in message
news:3A3B036A...@grove.iup.edu...
Ian White, G3SEK
reference website):
>
>f (MHz) Loss (W) dB
>0.1 1 -0.00435
>1 1.2 -0.00521
>10 1.3 -0.00565
>20 1.5 -0.00652
>30 1.8 -0.00782
>50 2.2 -0.00957
>100 2.6 -0.01131
>200 3.5 -0.01523
>300 5 -0.02177
>400 7 -0.03051
>500 10 -0.04365
>1000 15 -0.06564
>1250 18 -0.07889
>1500 28 -0.12334
>1750 39 -0.17277**
>2000 100 -0.45757**
>
>** Connector failed before calorimeter stabilized.
The full text shows that these are the directly measured heat losses in
the connector itself, and sure enough they are low... but that's only
part of the story.
The other part of the loss is due to the impedance bump that the
connector creates. Most of this does not appear in the connector itself,
but elsewhere in the system.
Here's another one from the archives, which measures the true insertion
loss (essentially the loss when a connector pair is inserted into a
continuous piece of coax connected between a 50 ohm source and load).
*********************************************************************
Date: Fri, 18 Sep 1992
Subject: The Truth about UHF Connectors
Ya gotta feel sorry for UHF connectors. Recent strings on this notes group
lambasted them as worthless at VHF and above, and barely tolerable at HF. One
poster called them "5 dB attenuators", and many agreed that there must be some
sort of conspiracy among ham equipment manufacturers to inflict such garbage
connectors on the amateur community.
Today I finally remembered to bring some UHF adapters from home so I could do
some relative measurements of UHF versus type-N. As expected, the type-N
showed lower insertion loss at high frequencies, but the UHF connectors were
hardly "5 dB attenuators."
For the test I connected an HP8753 RF network analyzer through
two short BNC cables into the following arrangement:
_______ ____________ ___________ ____________ _______
| | | BNC female | | N female- | | N male to | | |
__| 10 dB |__| to N male |__| N female |__| BNC female |__| 10 dB |__
| Atten.| | adapter | | adapter | | adapter | | Atten.|
|_______| |____________| |___________| |____________| |_______|
Then I repeated the measurement with the N adapters replaced with UHF.
I normalized the measurements by replacing the 3 adapters with a BNC
double-female. (That is, this was assumed to have 0 dB loss.)
Since two N or UHF adapters were used, I assume the loss per connector
is half the total. The vertical scale was .1 dB/division, so I
estimated the insertion loss to the nearest .01 dB or so:
--------- Type N ---------- ---------- UHF ------------
FREQ (MHz) TOTAL LOSS PER CONNECTOR TOTAL LOSS PER CONNECTOR
1.8 0 dB 0 dB 0 dB 0 dB
30 0 0 0 0
100 0 0 0 0
150 0 0 .02 .01
200 0 0 .03 .015
450 0 0 .18 .09
600 0 0 .26 .13
900 0 0 .66 .33
1000 .05 .025 .8 .4
1300 .1 .05 .86 .43
1600 .05 .025 .5 .25
2000 .05 .025 .02 .01
Insertion loss increases until about 1200 MHz, and then starts to decrease
until it is almost zero for the UHF connector at 2 GHz! At this frequency,
the connectors are about 1/4 wave long (1 inch, assuming .66 velocity factor),
so I assume that the two adapters are providing a conjugate match to each
other. This confirms my assumption that the insertion loss is due to
reflections (impedance mismatch), not absorption (true power loss).
AL N1AL
*********************************************************************
We keep coming back to the same bottom line: 'UHF' connectors are OK
through VHF, and even higher, but only if you can tolerate the impedance
bumps. Often they are OK, but sometimes not.
Where this discussion goes off the rails is when somebody tries to
shorten all that down to a simple Yes or No - because *both* of those
are wrong answers.
Roy Lewallen
power (or dissipative) loss. There's a lot of misunderstanding about
this, so I'd like to elaborate just a little.
Let's suppose you have a 50 ohm output laboratory generator that puts
one mw into a 50 ohm load. Connect it to a 50 ohm load through a
lossless 50 ohm transmission line. Now without changing anything else,
add an inductor having 35 ohms of reactance in series with the load at
the load end of the line. The power in the load is now 0.891 mW, which
is 0.5 dB less than before, so the inductor is said to have an insertion
loss of 0.5 dB.
But where's the loss? The inductor doesn't have loss. The current in the
circuit has actually decreased, so there's less power in both the source
and load resistances.
The answer is that there isn't really any loss -- the generator is
putting out less power than it did before, causing less power to end up
in the load resistor. But the smaller resistor power is often
conveniently accounted for as "insertion loss" or "mismatch loss". There
isn't anything wrong with this -- it's a common and useful concept. But
it's very important to realize that mismatch loss doesn't mean that
power is really being dissipated.
Now repeat this experiment substituting your 100 watt rig for the
laboratory generator. Assuming a modern solid state rig, the ALC will
maintain a constant forward power over a moderate range of SWRs. In this
case, the SWR is 1.99, so it should produce its nominal forward power of
100 watts. But the reverse power is now 11 watts, so you have a net
power in the load of 89 watts, a 0.5 dB reduction. (This is also the
total power being produced by the transmitter.) Again, it's because the
power out of the rig is actually less than before, not that you've
introduced loss in the system. In this respect, the amplifier with ALC
acts just like a 50 ohm laboratory source. [I was surprised by this, but
a little algebra shows that it's true for any complex load impedance. It
turns out that the forward power from a Thevenin source is constant for
any load Z, so the output I-V characteristics of a typical ALC
controlled transmitter -- one with constant forward power -- are the
same as a 50 ohm Thevenin source.]
But suppose you have a tuner anywhere in the circuit. You can, with the
tuner, make the transmitter see a perfect 50 ohm load, restoring its
power output to 100 watts (100 watts forward minus zero watts reverse).
Presto, the load power is back to 100 watts. If the tuner is at the
transmitter, the mismatch is still the same at the end of the line, and
the line still has a 1.99 SWR. But the mismatch "loss" is gone. So we
can undo mismatch loss with a tuner or other impedance matching
techniques.
If you take the inductor out but replace the connecting line with one
that has 0.5 dB loss (or use a lossless line and a series resistor), you
end up with the same power in the load as when you had the inductor in
series, but due to an entirely different reason. This time, the lab
generator or transmitter is putting out its full power, yet the load is
dissipating less than it was with lossless cable. Power is truly being
lost. Although you might be able to restore the load power by increasing
the transmitter or generator output, you'll always be wasting some of
the power as heat. No amount of fiddling with a tuner will make this
loss go away, as it did the mismatch loss. K7FR's figures represent
measurement of the actual dissipative loss caused by connector
resistance. Al's show the combination of this and the mismatch loss.
With a tuner or other impedance matching technique, you could reduce
Al's figures to the K7FR values.
It's not unusual to see frightening figures for connector loss which is
actually mismatch loss. A number of people have correctly stated that
the impedance bumps (which lead to mismatch loss) aren't significant if
they can be compensated for (by impedance matching). Loss due to
conductor resistance, though, can't be undone. Fortunately (but not
surprisingly, since the conductors are large), this real loss is tiny.
Roy Lewallen, W7EL
Bill Turner
>Wet rag potential problem there!
<snip>
> Not a wet rag its to fast of a cool and bad solder conductivity
>(cold solider joint) can certainly result!
______________________________________________________________
With all due respect, I disagree. Once the solder has solidified, the rate of
cooling is irrelevant, in my experience. Nobody, including me, is advocating
slapping a wet rag on a still-liquid solder joint.
w7ti
Dick Carroll
David wrote:
>
> Well just my 2 cents, I would use a N style connector where ever possible!
> The PL-259 is a bit lossy .25-.50 db loss depending how you install & solider.
>
> A RCA connector has better loss properties than a PL-259 hi hi.
>
David your two cents is worth as much as anyone else's. But are your
figures the result of numerous repeated accurate measurements, or
something you read, from whatever source? I had an engineer friend (now
SK) who wouldn't use a PL259 for ANYTHING. I didn't argue it with him,
but I've used both 259's and N's extensively on the job, and have had
far more operational problems with the N's-mostly those installed by
someone besides me at some earlier time.
A properly installed PL259 (many people do a terrible job installing
them, unfortunately) has done everything it was asked on all the gear
I've been around up thru UHF with no problems. N's have been more
troublesome and fragile, often after being in service for some time.
Of course the thread about 'too many of them in a feedline causing a
high SWR' is a factor to keep in mind. One on each end of the feedline
will be a more reliable installation than N's on each end, from what
I've seen.
For sure RCA's are something less than most reliable, whatever their
loss.
Dick
tom_b...@agilent.com
2w...@contesting.com (Tom W8JI) wrote:
> Better look again Tom. Inside the PL-259 the cable dimensions are
> exactly the same as the cable you have installed. That's true right up
> to the start of the pin.
>
> The entire problem is in the female connector, were at the mating
> female section it is a larger dimension. Zo there is typically in the
> 30-35 ohm range, but if the dielectric is removed (some connectors
> have a mostly air dielectric) impedance moves up close to 50 ohms.
(A bit wary of a virtual tar-baby here...) OK, so is that ever an issue
until the pair is mated? I never did disagree that the mated pair has a
problem with respect to impedance, and I'm well aware of the impedance
as a function of distance along a typical mated pair. But I'd for sure
say it's a _system_ design problem, not the "fault" of the female half
of the system. If there's blame to be laid, I'd lay it at the foot of
the system designer; but the fact that UHF connectors are STILL in very
common use after well over half a century says there must be something
right about them: inexpensive, reasonably rugged, ... As with nearly
everything, there are compromises in connectors. One size does not fit
all. I suspect we're in good agreement on that.
And as I wrote before, IF the designer of a transmitter/transceiver and
the designer of an antenna properly took the effects into account (as
noted before, they are the ones that have control over the female ends
that are part of their pieces of equipment), the performance of UHF
connector systems at 440MHz can be just fine for ham applications, SO
LONG AS the ham that uses them doesn't screw things up by putting a
bunch of barrel connectors along the line. But a single line with
connector at the transmitter and another connector at the antenna and
nothing but low loss line between will be fine for most ham
applications. Now if you think I use UHF connectors on my spectrum or
network analyzers...
BTW, I had previously written something about "two 1-inch-long 25 ohm
segments" potentially causing greater than 2:1 SWR at 450MHz. The
example I ran that gave the 2+:1 SWR was with two half-inch-long
segments, more like just a single mated pair at each of two locations
along the line.
Cheers,
Tom W8JI
>Wet rag potential problem there!
>
>Well this can also cause cold solider contact in most cases.
We used that method in production of panel meters and never got cold
joints. When soldering a delicate device, we would lay the device on a
wet sponge while applying heat with only the joint area clear of the
sponge.
The main thing that causes a cold joint (assuming it was heated enough
and clean) is moving the joint while it is cooling, not how fast you
remove heat after the solder flows. This isn't concrete!
How fast you cool the joint has nothing to do with joint quality as
long you don't disturb the solder while it is hardening.
73 Tom
Tom W8JI
>
>Well just my 2 cents, I would use a N style connector where ever possible!
>The PL-259 is a bit lossy .25-.50 db loss depending how you install & solider.
>
>A RCA connector has better loss properties than a PL-259 hi hi.
>
>Just my 2 cents...sk
Not true at all David. That is a popular but totally false "hamlore".
The loss in a UHF connector is immeasureable on conventional meters,
and that's true almost no matter how it is installed. The exception
would be if the connector was open or shorted.
One thing that will help you sort out rumor from fact is looking at
the numbers. Let's consider the .5 dB loss you quoted. That's almost
10% power loss.
If I ran 1500 watts through one of "your" PL-259's, it would dissipate
150 watts of heat.
Now let's consider how hot a 150 watt lightbulb gets, even though it
has dozens of times more surface area than the 259! Try this test, run
1500 watts through the connector and immediately grab it with you hand
after removing power. Now do that with a 150 watt lamp.
Let's try to not propagate such utter nonsense as .25 to .5 dB loss to
people trying to lean. At HF, the N connector is actually lossier than
a UHF connector. That's why a N connector will be unreliable at 5kW,
and a good UHF connector won't even get warm.
The exception are junk connectors like those from Radio Shack, which
fail at about a kilowatt or so.
73 Tom
Tom W8JI
>(A bit wary of a virtual tar-baby here...) OK, so is that ever an issue
>until the pair is mated? I never did disagree that the mated pair has a
>problem with respect to impedance, and I'm well aware of the impedance
>as a function of distance along a typical mated pair. But I'd for sure
>say it's a _system_ design problem, not the "fault" of the female half
>of the system.
It's almost ALWAYS the female's fault, even when discussing UHF
connectors. Look at the design.
The females have to fit around the male, and so the OD of the gripping
contact is larger than it should be for 50 ohms. The male is perfect
right up to the pin, and that pin is totally enclosed in the female.
Even a male-to-male adaptor has a much smaller bump than a female-to-
female.
My point isn't to disagree about impedance-critical cases when the UHF
is not a good idea, but to dispell these nonsense rumors that N
connector are from Heaven and UHF connectors from hell.
The fact is, if the connector is in a communications system below 150
MHz or so, no one would even be able to tell the difference in
performance.
In communications systems below 100 MHz, the N connector is a more a
sign of anal-retentiveness in the person picking the connector than
wisdom.
73 Tom
tom_b...@agilent.com
2w...@contesting.com (Tom W8JI) wrote:
> ... Look at the design.
Indeed! :-) I see we are in perfect agreement then.
Cheers, and Merry Christmas
Bill Turner
>The main thing that causes a cold joint (assuming it was heated enough
>and clean) is moving the joint while it is cooling, not how fast you
>remove heat after the solder flows. This isn't concrete!
________________________________________________________
Another factor in making good joints is using 63/37 alloy solder, NOT 60/40 or
something else. 63/37 solder is eutectic, which means it has the same melting
and freezing point. Other alloys, believe it or not, melt and freeze at
DIFFERENT temperatures and this can lead to fractured joints because they have a
longer time period in which they could be disturbed. 63/37 goes from liquid to
solid almost instantaneously (close enough for our purposes).
73, Bill W7TI
Jerry Flanders
the components of this alloy has the lowest melting point of all
possible ratios of these components. In other words, 63/37 is the
lowest melting temperature solder made of these two metals.
Jerry W4UK
tom_b...@agilent.com
jflan...@home.com (Jerry Flanders) wrote:
> I think "eutectic" only means that this particular ratio (63/37) of
> the components of this alloy has the lowest melting point of all
> possible ratios of these components. In other words, 63/37 is the
> lowest melting temperature solder made of these two metals.
It's the composition which is completely melted at that lowest temp.,
but for instance, 60-40 starts to melt at the same temp, with solid and
liquid existing together over a range of temps. Look at a tin-lead
"phase diagram" for further info...you can probably find one on the net!
There's one, for example, at
http://www.umist.ac.uk/MatSci/research/intmic/phase/pbsndiag.htm
Bill Turner
>for instance, 60-40 starts to melt at the same temp, with solid and
>liquid existing together over a range of temps.
________________________________________________________
Right, and this is what you don't want - a range of temps with liquid and solid
existing together. 63/37 doesn't have this and that's why it is preferred.
Don't feel bad if this is a little puzzling. The solder industry took a long
time to figure it out too.
73, Bill W7TI
Tom W8JI
Are you supposed to solder connections?
Bill Turner
>Are you supposed to solder connections?
________________________________________________________
I'm assuming you hit "send" before you were through...?
73, Bill W7TI
Leland C. Scott
> On Mon, 18 Dec 2000 23:42:06 GMT, tom_b...@agilent.com wrote:
>
> >Seems to me it's pretty hard to blame it on the female end. Either
> >the male or the female, unmated, will cause a rather large reflection!
> >But in the mated pair, I've seen impedances as low as about 25 ohms,
> >maybe a bit lower, and the 40-ohm end of the range is mighty rare in
> >those I've looked at.
>
> Better look again Tom. Inside the PL-259 the cable dimensions are
> exactly the same as the cable you have installed. That's true right up
> to the start of the pin.
>
> The entire problem is in the female connector, were at the mating
> female section it is a larger dimension. Zo there is typically in the
> 30-35 ohm range, but if the dielectric is removed (some connectors
> have a mostly air dielectric) impedance moves up close to 50 ohms.
>
> >If you do have a UHF mated pair that's 25 ohms for, say, 1 inch length,
> >and if the velocity factor is 0.5 (typical insulation in UHF connectors
>
> The only way you'd have a bump one inch long of 25 ohms with a Vp of
Well just for fun I did some calculations at various frequencies for a
system composed of a 1 inch long UHF barrel connector, with a PL-259 plug on
each end. The dielectric length of the PL-259 plugs I measured was 0.25
inches, and the barrel connector was 1 inch long. Each plug, and the barrel
adapter, were treated as a transmission line. The three "transmission" lines
were cascaded in series, a PL-259 plug on each end of the barrel adapter. A
"perfect" 50 ohm load was assumed connected to one PL-259 plug, and the SWR
meter was connected at the end of the other PL-259 plug. The input impedance
for each "transmission" line was calculated starting with the perfect 50 ohm
load, and then used as the load impedance for the next "transmission" line.
The length of the "transmission" lines were converted to the equivalent
wavelength based on the test frequency, and VF of the line. The loss less
transmission line equation was used for all the calculations below.
The dielectric constants I used were pulled from a copy of the book
"Reference Data for Radio Engineers" published by ITT.
Er=1.0 (air)
Er=2.1 (Teflon up to 3 GHz)
Er=4.6 (Phenol with 65% mica fill at 1 MHz)
Er=4.04 (Phenol with 65% mica fill at 100 MHz)
Er=3.57 (Phenol with 65% mica fill at 3.57 GHz)
VF=1/sqrt(Er) was assumed too.
I did find references, on the Amphenol Connectors web site, where they use a
mica filled dielectric in some of the UHF connectors they manufacture. You
should be able to look up specific connectors, then look under the
specifications, to see what types dielectric materials you can get them in.
The dimensions I measured on a barrel connector I took apart were; adapter
pin OD equals 0.217 inches, and the adapter shell ID equals 0.47 inches.
(Zadapter in ohms with an Er of adapter of)
( 1.0 2.1 4.0 )
46.37 31.998 23.185 (ohms)
The calculations were made at 430 MHz, 222 MHz, 144 MHz, 50 MHz, and 28 MHz.
The dielectric constant of the material in the PL-259 plugs was assumed to
be 1.0 (air), for this test.
(Freq) (SWR with an Er of adapter)
(MHz) ( 1.0 2.1 4.0 )
430 1.052 1.207 1.469
222 1.027 1.108 1.253
144 1.017 1.07 1.162
50 1.006 1.024 1.054
28 1.003 1.013 1.03
Now repeating the calculations at 430 MHz, 222 MHz, 144 MHz, 50 MHz, and 28
MHz. The dielectric constant of the material in the PL-259 plugs was assumed
to be 2.1 (Teflon), for this test.
(Freq) (SWR with an Er of adapter)
(MHz) ( 1.0 2.1 4.0 )
430 1.253 1.548 2.047
222 1.125 1.263 1.498
144 1.079 1.165 1.307
50 1.027 1.055 1.099
28 1.015 1.03 1.054
Now finaly repeating the calculations at 430 MHz, 222 MHz, 144 MHz, 50 MHz,
and 28 MHz. The dielectric constant of the material in the PL-259 plugs was
assumed to be 4.0 (Phenol with 65% mica filled ), for this test.
(Freq) (SWR with an Er of adapter)
(MHz) ( 1.0 2.1 4.0 )
430 1.489 1.97 2.794
222 1.231 1.439 1.785
144 1.145 1.269 1.467
50 1.048 1.087 1.144
28 1.027 1.048 1.079
As you can see the mix of different dielectric types can result in widely
varying SWR's. It would appear that even Teflon dielectric for 70 cm use may
be no good with UHF type connectors, unless you have a perfect 50 ohm load.
The results for 2m, using Teflon connectors, however look aceptable. If you
take the time to examine the V/UHF type of connectors used on high quality
SWR meters, power meters, and antenna mounts, you will find the
manufacturers use a "web" dielectric type of design. This is to get the
impedance bump of the UHF connector as close to 50 ohms as they can get.
They can do this because the "web" dielectric design is mostly air.
Measuring SWR at V/UHF has to be done with care. If the SWR meter is at the
rig end of the line, and the splice point some distance away, the SWR will
look lower because some of the reflected power is lost in the coax cable. So
with reduced reflected power the SWR meter will show a better SWR that what
you really have.
If anyone wishes I have the Mathcad worksheet I used, which I can E-mail for
further calculations. You will have to let me know what version of Mathcad
you have since I have to save the worksheet in the format specific for a
given version, such as 2K, 8, 7, or 6 only.
--
73's,
Leland C. Scott
KC8LDO
>>kc8...@arrl.net<<
ARRL member
NCI member
"You ask what Morse Code is good for? I'll tell you. Morse
Code is used exclusively by Electronics Based life forms to
communicate amongst themselves using advanced Organic
Digital Signal Processors, running state of the art Artificial
Intelligence Software, to perform the highly complex
transmit encryption, receive decryption and error correction
functions."
Gary Peach
"Tom W8JI" wrote >
> The main thing that causes a cold joint (assuming it was heated enough
> and clean) is moving the joint while it is cooling, not how fast you
> remove heat after the solder flows. This isn't concrete!
>
> How fast you cool the joint has nothing to do with joint quality as
> long you don't disturb the solder while it is hardening.
Good electronic solder has 2% antimony to keep the joints bright.
i.e. 60/40 is really 59/39/2
If you hold the iron on for *too long* then you will boil off the antimony
and the joint goes dull.
The secret of a good joint is:
Support both parts of the materials to be joined so that they will readily
remain in that position without any assistance,
wipe the iron clean and bright on a wet sponge, if it cools listen for the
click of the thermostic control,
apply it to both halves of the material to be joined and bring them up to a
temperature (the temperature voltage anolog) just above the melting point of
the solder to be used.
Again listening for the click can help. This can be assured with a curie
point tip of the correct number, usually a number 6 or 7 and of the correct
shape to limit the heat flow (i.e the heat current analog),
and then having cut the dead bit of solder off (1/4") that has no resin
flux in it (boiled off by the previous joint),
apply the solder to the WORK and not to the iron.
NEVER carry solder to the joint on the iron, by the time it gets there the
antimony will have boiled off.
Once the solder flows remove the iron.
The resulting joint should suck a nice meniscus of solder around the the
materials being joined.
I I
___)I(___,I,___ Imagine the tops of the brackets are not there
)I( 'I' Imagine the bottoms of the brackets are not there
I I
There should be NO surplus of solder.
If the solder hasn't pulled into a meniscus then there is a good chance that
it is not a good joint. A sound mechanical joint will have the best
electrical properties. Usual reason for bad joint is failing to clean the
materials BEFORE you start to apply solder.
Working from the junk box particular care to cleaning is worth the effort.
Practice makes perfect.
To do the best joints it takes about a week of practice to get back onto
good form.
Gary7SLL
Roy Lewallen
> . . .
> Good electronic solder has 2% antimony to keep the joints bright.
> i.e. 60/40 is really 59/39/2
> . . .
Most interesting. In my several decades as an engineer and technician
(including military), I've never encountered solder containing antimony.
A quick look at a Newark catalog does show some 95Sn/5Sb alloys as lead
free solder for HVAC and food service equipment, but nothing like you're
describing. And that one 95/5 alloy is the only one containing antimony
shown on my Kester "Solder Alloys Guide". (Interestingly, there's a lot
of information on the Kester web site about lead free solders, along
with a statement that they feel elimination of lead containing solder is
inevitable.)
Are the solder vendors adding the antimony without telling anyone (which
I seriously doubt), or is this some special alloy you can buy? Is there
a eutectic combination with tin and lead? If so, what percentages of tin
and lead are required?
Roy Lewallen
Bill Aycock
2500 degrees, F, so the soldering iron that will do that is one I dont
want to hold in my hand. I would like to know where this bit of
'information' originated. Do you know?
Bill- W4BSG
Roy Lewallen
[Good and interesting calculations]
> . . .
> As you can see the mix of different dielectric types can result in widely
> varying SWR's. It would appear that even Teflon dielectric for 70 cm use may
> be no good with UHF type connectors, unless you have a perfect 50 ohm load.
> The results for 2m, using Teflon connectors, however look aceptable. If you
> take the time to examine the V/UHF type of connectors used on high quality
> SWR meters, power meters, and antenna mounts, you will find the
> manufacturers use a "web" dielectric type of design. This is to get the
> impedance bump of the UHF connector as close to 50 ohms as they can get.
> They can do this because the "web" dielectric design is mostly air.
> . . .
Many years ago, I was surprised to find an SO-239 antenna connector on a
surplus commercial 450 MHz transceiver. (As I recall, it was a Motorola
"twin V" -- originally used in a taxi or similar service.) But it's
apparent how they got away with it. The transmitter output matching
network could easily be adjusted to match whatever impedance was
presented by the combination of the connector and 50 ohm load, to effect
maximum power transfer. The connector wouldn't have any effect on the
transmission line SWR, being at the transmitter end. Similarly, the
receiver input impedance could be adjusted so that the load seen by the
antenna when receiving was 50 ohms, again resulting in a 1:1
transmission line SWR and proper load for the antenna. So no harm was
done.
If there was a connector at the antenna and the antenna had some means
of matching (a gamma match for example), it could be adjusted to
compensate for the connector. Again, the transmission line would have a
1:1 SWR and everything would be properly matched.
The trick is to have the connector close to the point where a
compensating matching network can be placed (or at a point where a
network already is -- a network that can be adjusted or designed to
compensate for the connector). If you can do that, you can use pretty
badly mismatched connectors or other components with very little
performance degradation. (If the match is really gross, you can incur
loss or narrowbandedness from the matching network.) The farther apart
the matching network and mismatched component, the more narrowbanded the
compensation. You'll also have an elevated SWR on the transmission line
between them, which will result in added loss if the line loss is
significant to begin with.
So whether a mismatched connector or other component is a problem
depends largely on whether you have a compensating network, and where it
is relative to the connector or other component.
Thanks for the quantitative data!
Roy Lewallen, W7EL
Jim Pennino
> GAry- please get it right before you preach- Antimony boils at about
> 2500 degrees, F, so the soldering iron that will do that is one I dont
> want to hold in my hand. I would like to know where this bit of
> 'information' originated. Do you know?
> Bill- W4BSG
<rest snipped>
Getting antimony into solution in the first place is a bit of a chore, but
once there, the melting point of the alloy is not much affected.
Don't recall seeing any solder with antimony in it, but lineotype (SP?)
metal had quite a bit by design (makes the alloy harder and molds "crisper").
And a soldering iron will melt it.
Bullet casters prefer lead alloys with a bit of antimony for the same reasons.
Ever hear of silver solder? You can't melt pure silver with any ordinary
soldering iron either, but once alloyed with lead and/or tin....
Jim Pennino
Hassen Ben Sober
But- What I use- You ain't gonna melt with a Soldering Iron :-)
The Melting Temp of Silver Solder is Damn near the Melting temp of Copper.
That's why it's used in High Pressure AC Systems :-)
"Jim Pennino" <ji...@mail.specsol.com> wrote in message
news:sq1d29...@mail.specsol.com...
Roy Lewallen
solder alloys like you're describing. The ones I've worked with can be
melted with a propane torch but not a soldering iron. But there are
tin-lead solder alloys containing 2 or 3% silver to prevent leaching the
metallization off of gold or silver-terminated surface mount parts. This
has a melting point near that of plain tin-lead solder. Some people
(mistakenly, in my opinion) call this "silver solder", confusing it with
the high temperature alloys. They're very different things.
(There are also other low temperature alloys containing small amounts of
silver, but mostly for special purposes and not often seen in
electronics.)
Roy Lewallen, W7EL
Jim Pennino
> Donno about your Silver Solder-
> But- What I use- You ain't gonna melt with a Soldering Iron :-)
> The Melting Temp of Silver Solder is Damn near the Melting temp of Copper.
> That's why it's used in High Pressure AC Systems :-)
The silver solder used in electonics, as opposed to plumbing and whatever
else, usually runs from 2% to 6% silver and uses ordinary electronic
soldering techniques and equipment.
OK, OF role call; how many of you worked on a Tek 'scope with the little
roll of silver solder under the cover for replacing compenents on the little
silver metalized ceramic strips?
Jim Pennino
Jim Pennino
> "Silver solder" is a term traditionally applied to high-temperature hard
> solder alloys like you're describing. The ones I've worked with can be
> melted with a propane torch but not a soldering iron. But there are
> tin-lead solder alloys containing 2 or 3% silver to prevent leaching the
> metallization off of gold or silver-terminated surface mount parts. This
> has a melting point near that of plain tin-lead solder. Some people
> (mistakenly, in my opinion) call this "silver solder", confusing it with
> the high temperature alloys. They're very different things.
> (There are also other low temperature alloys containing small amounts of
> silver, but mostly for special purposes and not often seen in
> electronics.)
> Roy Lewallen, W7EL
<Other stuff snipped>
Geez Roy, I thought we were talking about electronic stuff here.
Is this rec.plumbing.amateur ? :-)
Properly, the stuff used in electonics should be called "silver baring
solder", but since there weren't any plumbers around to correct us, we
called it "silver solder".
You are quite correct; the purpose is to prevent leaching from a substrate.
About the only place most people have ever seen it is the silver coated
ceramic component carriers used in OLD Tec 'scopes and some old military
gear.
It is still used in the manufacture of thick film devices and things of
that ilk. Those dip/sip resistor packs, for example, have their leads
crimped to a plated ceramic substrate and then "silver soldered" (sic).
Sometimes "gold solder" (sic) is used for parts where silver migration
is a problem, but not often because of the cost.
If you like, I can bore you for hours with tales of watching silver migrate
across substrates though a microscope and trying to figure out how to keep
it from happening without using gold while the Vandegraff generator across
the lab to simulate lightning effects on parts caused the secretaries hair
to stand straight up and brought threats of violence on my person....
Jim Pennino
Richard Clark
<ji...@mail.specsol.com> wrote:
>
>OK, OF role call; how many of you worked on a Tek 'scope with the little
>roll of silver solder under the cover for replacing compenents on the little
>silver metalized ceramic strips?
>
>Jim Pennino
Yo!
73's
Richard Clark, KB7QHC
CJ
I never actually worked on any of those units but I read the threats
about what would happen if I didn't use the proper solder. Scared the
hell out of me!
73, CJ K0CJ
> Jim Pennino
Leland C. Scott
"Roy Lewallen" <w7...@eznec.com> wrote in message
news:3A49CDEC...@eznec.com...
> "Leland C. Scott" wrote:
>
> [Good and interesting calculations]
>
>
> of matching (a gamma match for example), it could be adjusted to
> compensate for the connector. Again, the transmission line would have a
> 1:1 SWR and everything would be properly matched.
>
> The trick is to have the connector close to the point where a
> compensating matching network can be placed (or at a point where a
> network already is -- a network that can be adjusted or designed to
> compensate for the connector).
The above is very true. Since you would have a non-50 ohm load on the line,
the line would "transform" the impedance. So the closer you can keep the
mismatch to the matching network, the less the transmission line will alter
the impedance.
Gary Peach
"Bill Aycock" wrote
> GAry- please get it right before you preach- Antimony boils at about
> 2500 degrees, F, so the soldering iron that will do that is one I dont
> want to hold in my hand. I would like to know where this bit of
> 'information' originated. Do you know?
>
> Bill- W4BSG
Well Bill NASA spent a great deal of money MUS$ investigating solder, and
soldering reliability.
As I was working for them back in the 60s and 70s I was sent on a weeks
course to learn about soldering and how to solder. There was an examination
and a few test pices to complete at the end of the course. That fact that I
passed with a good mark, and my memory though not perfect is not so bad that
I would forget the few useful bits of information that I picked up.
Still we are probably discussing an obsolete technology if lead is to be
eliminated from electronic equipment.
Of course the fact that in the olden days, (50s) one was taught (not NASA)
to produce a third hand by holding the resin core solder in the mouth is
ample evidence that everything that we are taught is not always true, and
that one man's meet is another's poison.
And please don't acuse me of having a mental condition prematurly brought on
by lead poisoning. ;)
--
Gary7SLL
1° 20' W 51° 23' N
http://www.gary.peach.dial.pipex.com/
Gary Peach
of the osciloscope in order to solder components onto the ceramic tag boards
that they used in their equipment.
Silver solder can be soldered with a number 9 curie point tip.
Of course some of us have been around long enough to have done it;
not just read about it.
--
Gary7SLL
1° 20' W 51° 23' N
http://www.gary.peach.dial.pipex.com/
"Hassen Ben Sober" <HassenB...@kumputer.net> wrote in message
news:u%v26.28250$3B5.1...@newsread2.prod.itd.earthlink.net...
Gary Peach
How many of you repaired and calibrated them to a seconadry traceable
standard?
The handbooks that came with them were super, why more companies don't
introduce a little humour into ther tech data I do not know. A full day at
the bench can be tiring enough, the light relief from the humourous drawings
was a welcome.
--
Gary7SLL
1° 20' W 51° 23' N
http://www.gary.peach.dial.pipex.com/
"Jim Pennino" <ji...@mail.specsol.com> wrote in message
news:s08e29...@mail.specsol.com...
Gary Peach
I have used the powdered silver for putting flanges on Q Band Silver wave
guide and certainly that would only melt with a torch.
--
Gary7SLL
1° 20' W 51° 23' N
http://www.gary.peach.dial.pipex.com/
"Richard Clark" <rwc...@seanet.com> wrote in message
news:3a506db9....@news.seanet.com...
Wes Stewart
>Tectronix used to supply silver solder on little bobbins that formed a part
>of the osciloscope in order to solder components onto the ceramic tag boards
>that they used in their equipment.
>Silver solder can be soldered with a number 9 curie point tip.
>
>Of course some of us have been around long enough to have done it;
> not just read about it.
I have done it too. However, I used *silver-bearing solder*, not silver solder
like I use to solder copper pipe with a MAPP torch.
Wes N7WS
Bill Aycock
I have not found a reference to solders with this element , in what was
a limited search. Antimony is used in several lead alloys that are
commonly cast, because Sb, like water, but unlike most substances,
expands when it solidifies on cooling. Thats why it is used in type
metal, and in bullet casting- it gives a 'crisp' surface that is true to
the die.
I have been using non-lead solders in some projects I am involved in,
because they concern objects that are handled, and there are regulations
that dictate 'lead-free'. I actually find the newer solders easy to work
with, unlike some of the reports I have seen.
When I was active in Aerospace work, we had to have certified solderers.
I was not one of them, but it was something we had to specify and
certify. We sent many operators to Marshal Space Flight Center classes.
As to the 'Lead poisoning', I may have been more at risk than you- at
one time- MANY years ago, I used white lead in some activities. We were
very ignorant, and I now find that scary.
Bill- W4BSG
Roy Lewallen
>
> On Sun, 31 Dec 2000 12:51:21 -0000, "Gary Peach" <xc...@dial.pipex.com> wrote:
>
> >Tectronix used to supply silver solder on little bobbins that formed a part
> >of the osciloscope in order to solder components onto the ceramic tag boards
> >that they used in their equipment.
> >Silver solder can be soldered with a number 9 curie point tip.
> >
> >Of course some of us have been around long enough to have done it;
> > not just read about it.
>
> I have done it too. However, I used *silver-bearing solder*, not silver solder
> like I use to solder copper pipe with a MAPP torch.
>
> Wes N7WS
Yes, this is the 2 or 3% Ag solder I mentioned in an earlier post.
Without the small amount of silver, the metalization on the ceramic
terminal strips would dissolve in the solder, and would be gone from the
strips the first or second time you soldered them. But the silver has
only a small effect on the melting point. Sn63/Pb37 solder is turns
solid and liquid at 183 degrees C; Sn62/Pb36/Ag02 turns solid at 179 and
liquid at 189.
Roy Lewallen, W7EL
Gary Peach
"Wes Stewart" wrote
> >Of course some of us have been around long enough to have done it;
> > not just read about it.
>
> I have done it too. However, I used *silver-bearing solder*, not silver
solder
> like I use to solder copper pipe with a MAPP torch.
Sorry that was not directed at anyone in particular Wes,
just one of those generalities.
Only the names have been changed to protect the innocent.
I thought it was the three wise men that came bearing gifts. ;)
Of course you are quite correct about my slack use of the words
"Silver-Solder", I'm afraid you'll have to put that down to the common usage
of that time, a sort of jargon/ shorthand used by insiders and taken to mean
"Silver Baring Solder".
Gary Peach
Thanks Bill nice informative post,
> As to the 'Lead poisoning', I may have been more at risk than you- at
> one time- MANY years ago, I used white lead in some activities.
> We were very ignorant, and I now find that scary.
Well Bill you'll have an excuse, unlike me a bit ecentric,
(runs in the family I'm afraid), but the less charitable might say,
"just plain barmy". ;)
As for being ignorant back then, what about the open wide mouthed bottles of
Benzine and Carbon Tet that used to adorne our work benches.
The Certification that NASA required was for all Technical personelle even
if they rarely did any bench work. This happened one day aftera conversation
with my Boss and a few other engineers. I casually said that although I had
been permitted to design things in the aerospace Industry they were wise
enough to not lket me loose with a soldering Iron even thoughh I had passed
the RAF Workshops p[ractices with flying colours. About three weeks elapsed
and all personell were sent on courses a few at a time for a week each. It
made a nice break from the inevitable shift work that goes along with
tracking spacecraft in interplanetary space.
Bill Ogden
grade melting point
IT 1490F
Hard 1425F
Medium 1390F
Easy 1325F
Extra Easy 1270F
Sterling silver (7.5% copper) melts at 1640F and fine silver at 1762F.
That must be some soldering iron you guys use to work with silver solder!!
(I use a torch, myself; and nowhere near any electronics.)
"Soft solder" (sometimes with just a little silver in it) is a different
story, but this is definitely not "silver solder."
Bill
W2WO