Homebrew tuners
Art Unwin KB9MZ
to operate on many bands with just a long wire and a tuner.
The wire is inexpensive but the tuners are not. Thus my present
project.
I was given a Palomar enginnering balun with 5 female connenection
which by selection can match a antenna in steps from 5 ohms to over
450 ohms
in a series of steps. I am presently rigging it up so that all
steps can be switched thru remotely by a single motor. The switching
arrangement
is the main challenge since inexpensive means simple.
Now I have not measured losses of the balun before hand because the
switching
challenge is what is driving me.
Anybody have any thoughts about what I should expect from this
balun other than knowing that it is not a tuner as is generally known
since
it does not have the ability to obtain the priceless 1:1 condition
that so many desire?
Regards
Art
George, W5YR
r-f transformer.
A balun, of course, is completely different from a transformer in that it is
a "transmission line transformer" which is made of short transmission line
sections instead of "windings."
If a balun is made with line sections of Zo, then the load must be an
appropriate multiple of Zo and purely resistive for the balun to function
properly.
Usually it is best to let a balun do the current steering and keep the outer
braid of the coax "clean" and do the impedance matching elsewhere, as in a
tuner.
Just a thought . . .
--
73/72, George
Amateur Radio W5YR - the Yellow Rose of Texas
Fairview, TX 30 mi NE of Dallas in Collin county EM13QE
"In the 57th year and it just keeps getting better!"
<mailto:w5...@att.net>
"Art Unwin KB9MZ" <aun...@insightbb.com> wrote in message
news:85ed38d.03072...@posting.google.com...
Mark Keith
> Seems like a lot of hams with limited resources are still compelled
> to operate on many bands with just a long wire and a tuner.
> The wire is inexpensive but the tuners are not. Thus my present
> project.
> I was given a Palomar enginnering balun with 5 female connenection
> which by selection can match a antenna in steps from 5 ohms to over
> 450 ohms
> in a series of steps. I am presently rigging it up so that all
> steps can be switched thru remotely by a single motor. The switching
> arrangement
I'd rather wind a coil, "oatmeal tube carton"? and find a good
variable cap, and make a simple L network to feed a random wire. I'd
rather not use an apple to do a job that an orange should rightfully
have. :/ MK
Art Unwin KB9MZ
It says in very large letters on it " TRANSFORMER"
Since transformers are touted as being efficient
I was wondering how it would compare with
the normal tuner. Half of the challenge for me
was to come up with an inexpensive switching
system where the input was stationary while the rest
were switched thru and then repeated for the next
input e.t.c. With that being solved I look forward
to finishing and then playing with it
Regards
Art
"George, W5YR" <w5...@att.net> wrote in message news:<aoHVa.76443$3o3.5...@bgtnsc05-news.ops.worldnet.att.net>...
W5DXP
> Since transformers are touted as being efficient
> I was wondering how it would compare with
> the normal tuner.
Who touts transformers as being efficient? And efficient
compared to what?
--
73, Cecil http://www.qsl.net/w5dxp
-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
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Dave Shrader
"When I was a youngster, back in the olden golden days, transformer
efficiencies exceeded 98%, but that was for 60 Cycle [olden days
language] power distribution systems."
<H U G E G R I N >
Deacon Dave, W1MCE
+ + +
W5DXP
> Define 'Efficient' before you engage in this discussion.
OK, let's say as efficient as a transmission line transformer
over an entire range of frequencies. I don't think you will
find a normal transformer that is as efficient as a transmission
line transformer over the entire HF frequency range. But I could
be wrong.
Dave Shrader
design, I recall that core loss increased as an exponential of
frequency. The exponential was greater than '1.2' and less than '2.0'.
Now, magnetic materials have changed, since the invention of the wheel,
but I still suspect that losses in magnetic materials are exponential,
even in new materials.
So, in a transformer I would expect core loss to increase exponentially
from 1.8 to 29.7 MHz.
In a balun, well I don't know!
Shortly after the invention of the wheel I came into the ownership of a
B&W air wound balun rated at 250 watts continuous that I used for over
35 years. I dumped it as part of the move from Massachusetts to New
Hampshire. That was DUMB! But, using air instead of magnetic material
certainly minimized losses <grin>.
Back to the Modern Age. How efficient is a transmission line
transformer? [TBD %] Can you quantify a suitable number or will it
remain a qualitative statement?
Deacon Dave, W1MCE
+ + +
W5DXP
> Back to the Modern Age. How efficient is a transmission line
> transformer? [TBD %] Can you quantify a suitable number or will it
> remain a qualitative statement?
Looking at some of the graphs in Jerry Sevick's book, _Transmission_
Line_Transformers_, it looks like about .05 dB maximum loss from 3
to 30 MHz. Note that figure is for perfectly matched resistive loads.
A transmission line transformer carries a high flux density for common
mode but not for differential mode. An ordinary transformer carries
a high flux density for differential mode. That's got to make a
difference.
Richard Clark
<david....@comcast.net> wrote:
>Back to the Modern Age. How efficient is a transmission line
>transformer? [TBD %] Can you quantify a suitable number or will it
>remain a qualitative statement?
Hi Dave,
Jerry Sevick offers a multitude of designs, all specified for loss
over frequency. One such example illustrated in Fig. 11-6 shows a
50:12.5 Ohm with an insertion loss of around 0.1dB or less over the
interval of 100KHz to 30MHz. And this is not the best example of low
loss.
73's
Richard Clark, KB7QHC
Dave Shrader
DD, W1MCE
Reg Edwards
transmission line HF transformers (voltage Baluns), download program BALUN4
from website below -
---
=======================
Regards from Reg, G4FGQ
For Free Radio Design Software
go to http://www.g4fgq.com
=======================
NN...@reno.rmci.net
hearing, sight, ect. ), anyhow, Just what would be the Noticeable effect of
>/ = .1 dB in the real world ? Would , say, 2/10's really kill you, or
1/100th dB extra get you that last DXCC country? As I say, am very cynical
when ANYTHING gets into these kinds of numbers! Jim NN7K
KB7QHC wrote:
-------------------------------------------------
50:12.5 Ohm with an insertion loss of around 0.1dB or less over the
interval of 100KHz to 30MHz.
AND THAT IS NOT THE BEST EXAMPLE OF LOW LOSS!
Jimmy
segments for impedance matching. That is about as cheap as it gets.
"Art Unwin KB9MZ" <aun...@insightbb.com> wrote in message
news:85ed38d.03072...@posting.google.com...
Richard Clark
Hi Jim,
Cynical? This 0.1dB corresponds to about 2% error from perfect where
too many think that 5% error is the worst they have to suffer from
making a power measurement with their Bird (which actually doesn't do
nearly that well in the first place due to these accumulations of
error). It doesn't take long for error to accumulate to the 10's of
percent where you couldn't convince the bench tech that he has too
many places of precision in his pronouncement of measuring 104.5W
(when it was in fact closer to somewhere between 85W to 115W).
I can well anticipate the "so what?" rebuttal. "Who needs 5%
accuracy?" being another. The general rule of thumb demands that your
standard exhibit 3 times the accuracy of the instrument being
calibrated (the Bird is already dead on arrival using this 0.1dB loss,
if it were not characterized already). With an out of whack Bird, you
barely qualify any power measurement to within 15% (and there are more
sources of error than the BalUn used to isolate the Bird). Again, I
am being generous with the 3 times rule (professionals generally seek
5 times and are more comfortable with 10 times). But this is all
really the provence of the professional Metrologist, not the Amateur.
For the Bench Tech that confidently made the 104.5W measurement (not
knowing it was in fact closer to 60W) would hardly know it through
contacts where they barely noticed the less than 1 S-Unit difference.
Returning to this 0.1dB, it also represents a heat burden of 20W (or
more, I am being generous) for each 1KW passing through. This is a
lot of heat for small packages carelessly regarded as being trivial
(after-all, who can see 0.1dB on their S-Meter?). There have been
more than single reports of Hams writing here in astonishment of their
BalUns exploding. Blame the BalUn seems to be a popular ballad played
to that audience. Others pronounce with hushed tones of reverence
remonstrating mankind for drifting from the true path of the air wound
BalUn (or choke, what will you) mindless of the same loss, but
gratified through ignorance of the greater heat mass.
This 0.1dB in the wrong hands is clearly an example of extravagant
dismissal or myopic attention. And speaking of hands, how long would
you consider it trivial if you had to hold onto the sucker for 20
seconds?
W5DXP
> I would suggest that anyone that strapped for cash use transmission line
> segments for impedance matching. That is about as cheap as it gets.
Yep, I bought an SGC-500 amp and didn't want to spring for a high power
tuner. So I vary my window-line length to obtain a match.
Art Unwin KB9MZ
people asking about the G5RV which is an inexpensive way of
of operating on many bands. I thought that maybe a inexpensive way
of matching such an antenna would be a cheap sort of tuner.
I don't need a tuner, it was just an idea that popped
into my head. Clark raised the subject of excess heat
that I hadn't thought of but I am enjoying the challenge
of putting together suitable mechanisms that would not be
subject to breakdown, that one could place at a antenna feed point.
If it explodes it would be more spectacular than having a
neon light blinking during radio operation !
If one must have 1: 1 SWR at all times then they can spend a $200
amount or more to buy the SGC tuner ( I thing that in the name
of the automatic tuner which I believe is limited with respect
to power.)
The mechanism I am making is a star shaped wheel with a slot in
each point.
It has a interconnecting rotary switch that sweep each transformer
connection and when it has rotated once engages the star wheel
so that it rotates a distance equal to the transformer connection
where it stays in place for the next rotary switch rotation.
Making the parts from a plastic sheet used to replace a glass
window pane plus the use of a small hand grinding tool.
Duing this in the garage to escape the heat
Jimmy" <Gfe...@carolina.rr.com> wrote in message news:<7smWa.367564$jp.10...@twister.southeast.rr.com>...
Art Unwin KB9MZ
> Jimmy wrote:
> > I would suggest that anyone that strapped for cash use transmission line
> > segments for impedance matching. That is about as cheap as it gets.
>
> Yep, I bought an SGC-500 amp and didn't want to spring for a high power
> tuner. So I vary my window-line length to obtain a match.
Cecil, the idea that you have is quite unique but I was thinking
of the newby ham. To capture the future hams of tomorrow we must
enable them to get them on the air as quickly and cheaply as
possible and not dissuade them in any way as to how much they
will be paying in the future, and that is where my thoughts lie.
If a newcomer is to put up a G5RV so that he can get on the
air quickly,I thought that buying a RF transformer would be a
quick way of getting on the air and getting the taste for ham radio.
To be honest Cecil no newby is going to struggle with your method
in his early days.
If one could arrange a way to run thru a series of impedance ratio's
with just one knob then we have hooked those who are curious, even
when using the most plainess of wires or the gutter we have fed the
mind, remote control systems can come later. Frankly when you are
hooked by ham radio money ceases to become an issue.
Art
Bill
If you are trying to communicate with another station and he is putting out
100 watts and is not being copied and then he puts out 110 watts and you can
copy him that is what counts.
Bill N4WC
Reg Edwards
> I think it all boils down to signal to noise.
> If you are trying to communicate with another station and he is putting
out
> 100 watts and is not being copied and then he puts out 110 watts and you
can
> copy him that is what counts.
>
Bill, sorry to be so pessimistic.
If, because of bad signal to noise ratio you can't copy him when he's using
100 watts, then, as sure as eggs don't bounce off concrete, there's no hope
of any detectable improvement by increasing power to 110 watts or 0.4 dB.
Suppose when he's using 100 watts you can hear only 25% of words (or morse
characters). So you can't copy him.
If he doubles power to 200 watts you will still read only 40% of what he
says. So you still can't copy.
If he doubles power again to 400 watts you will be able to copy 60% of what
he says. You will still be in big trouble.
At 800 watts 80% of words (or characters) will be OK but it's not solid
copy. Requests to repeat will be common.
At 1600 watts 99% of words (or characters) will be OK and that's solid
enough.
There are many assumptions in the foregoing crude analysis. But as many have
experienced it is typical.
Claude E. Shannon's (of Bell Labs) original classical paper on the subject
of "Communication in the Presence of Noise", Jan. 1949 can be downloaded (I
have just discovered) by doing a Google on the title. Radio and phone
engineers had been trying for 40 years to describe in precise mathematical
terms the effects of noise and cross-talk in a communication channels. The
transistor had just been invented. So had PCM pre-war. But progress in the
design of the vast communication digital networks then envisaged and which
we now see was being impeded by the lack of understanding of the effects of
ever-present random noise.
It was basically a problem in Statistics. But Shannon went off at a tangent
back to Geometry where Pythagorus the ancient Greek had begun. He translated
the statistical problem into one of calculating the number of small spheres
which can be packed inside a much larger multi-dimensional sphere. The
calculating procedure acquired the everlasting name of "Ball Packing". It is
not difficult to understand. It was Shannon's dazzling multi-coloured flash
of inspiration which did the trick. His name has gone down in history. Think
of him the next time your electric light dimmer-switch goes faulty.
Following Shannon progress forged ahead. In-words such as signal-to-noise
ratios and error-rates became very popular.
A one-dimension sphere is a dot. A 2-dimension sphere is a flat circular
disk. A 3-dimension sphere is a ball. Followed by N-dimensions, all of which
have a surface area and and a volume involving Pi.
----
Reg.
Ian White, G3SEK
>Suppose when he's using 100 watts you can hear only 25% of words (or
>morse characters). So you can't copy him.
>
>If he doubles power to 200 watts you will still read only 40% of what
>he says. So you still can't copy.
>
>If he doubles power again to 400 watts you will be able to copy 60% of
>what he says. You will still be in big trouble.
>
>At 800 watts 80% of words (or characters) will be OK but it's not solid
>copy. Requests to repeat will be common.
>
>At 1600 watts 99% of words (or characters) will be OK and that's solid
>enough.
>
>There are many assumptions in the foregoing crude analysis. But as many
>have experienced it is typical.
>
Typical for a machine, but not for a human being. For humans, "copying"
very weak speech or Morse is mostly about *understanding* it as
language.
In conversational speech, we don't always hear every word. Our minds are
remarkably good at filling in gaps by using the broader context of the
whole sentence. Even if you don't hear a word clearly, you can hear a
word was there and your mind will automatically make a good guess, based
on what we did hear before and after. It happens all the time, in
conversations both on and off the air, and you don't even notice
yourself doing it.
It's more obvious when copying Morse, where we more often fill in
individual letters, but sometimes also whole words. We make very clever
guesses about what the letter could have been, based on what we did
manage to hear.
Often there is a threshold effect. Below that threshold, you can hear
quite a lot but it doesn't make sense as language. Just above the
threshold, it clicks into context and you can understand a whole
stretch... and then maybe we lose it again.
It's also like listening to a language we only "half" know. That doesn't
mean we understand a certain percentage of individual words, as a
machine might. The way it really works with human beings, we're suddenly
delighted to find ourselves understanding whole sentences... and then,
just as suddenly, we lose it again completely.
The exceptions are for certain key items like a callsign, name, QTH or
contest exchange. These items come one by one (without context) and must
be logged with 100% accuracy, so then it's rather more mechanical like
Reg describes. But even for key words like phonetics, there is a
threshold between hearing a sound, and that sound resolving itself into
a recognisable word.
As any DXer knows, the threshold between "getting it" and "losing it"
can indeed be as little as 1dB. The more serious you are about working
right down to that threshold, the more that last 1dB matters.
--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek
WB3FUP (Mike Hall)
run my FT-817 with its 5 watt signal for a lot
less money than my friend Jim can operate his
kilowatt. If the band is open The difference
between my 5 watt signal and his 1000 watt signal
is 2 or three S units at the far end of the
circuit. Not enough to be really noticeable. If
the band is closed, nobody is talking long
distance, the band is closed. Now when conditions
are marginal he has a decided advantage. Right
now I am happy burning a kilowatt of power
purchased from the electric company every 15 hours
while he gets about 20 minutes operating time for
his station for the same dollars.
--
73 es cul
wb3fup
a Salty Bear
"Ian White, G3SEK" <G3...@ifwtech.co.uk> wrote in
message news:oNdgsoELv2K$EA...@ifwtech.co.uk...
Jimmy
Actually I would think a newbie would be the one most likely to embrace
Cecil's method. Its the guys who have been around a while who want
everything controlled at their armchair(like me). This is not to say that
Cecils method could not be controoled from the shack, Just replace some of
those switches with relays and maybe make some custum impedance feedline for
even a better match that what he shows though you dont really need it. This
sort of setup could even be controlled by a lot of radios that provide for a
means of automatic antenna switching.
Mark Keith
> W5DXP <Cecil....@ieee.org> wrote in message news:<3f2a4e49$1...@corp.newsgroups.com>...
> > Jimmy wrote:
> > > I would suggest that anyone that strapped for cash use transmission line
> > > segments for impedance matching. That is about as cheap as it gets.
> >
> > Yep, I bought an SGC-500 amp and didn't want to spring for a high power
> > tuner. So I vary my window-line length to obtain a match.
>
> Cecil, the idea that you have is quite unique but I was thinking
> of the newby ham. To capture the future hams of tomorrow we must
> enable them to get them on the air as quickly and cheaply as
> possible and not dissuade them in any way as to how much they
> will be paying in the future, and that is where my thoughts lie.
Sounds kinda like you want a "venus ham trap"....:/
> If a newcomer is to put up a G5RV so that he can get on the
> air quickly,I thought that buying a RF transformer would be a
> quick way of getting on the air and getting the taste for ham radio.
I think stringing up a coax fed dipole is about the easiest of all
antennas.
> To be honest Cecil no newby is going to struggle with your method
> in his early days.
I'm sure many would. It's not that hard to rig up.
> If one could arrange a way to run thru a series of impedance ratio's
> with just one knob then we have hooked those who are curious, even
> when using the most plainess of wires or the gutter we have fed the
> mind, remote control systems can come later.
Huh??? I thought this was already solved in my previous post where I
reinvented the L network. Even the poorest of hams can likely scrounge
an oatmeal carton.
Frankly when you are
> hooked by ham radio money ceases to become an issue.
Luckily, most antennas can be built for fairly low cost.
Now radios.....:(
I'm too lazy to build radios when nothing I can build is as good or
better than what I can buy. MK
W5DXP
> Actually I would think a newbie would be the one most likely to embrace
> Cecil's method. Its the guys who have been around a while who want
> everything controlled at their armchair(like me). This is not to say that
> those switches with ...
I control the switches from my shack. They are mounted on a piece of
plexiglas sitting vertical in a window. It takes less time to throw
the switches than to tune an antenna tuner.
CW
wants on the air multiband cheap, MFJ sells an L-network random wire tuner
for about $40.00.
"Mark Keith" <nm...@wt.net> wrote in message
news:25eb70d7.03072...@posting.google.com...
Jimmy
> Jimmy wrote:
> > Actually I would think a newbie would be the one most likely to embrace
> > Cecil's method. Its the guys who have been around a while who want
> > everything controlled at their armchair(like me). This is not to say
that
> > Cecils method could not be controlled from the shack, Just replace some
of
> > those switches with ...
>
> I control the switches from my shack. They are mounted on a piece of
> plexiglas sitting vertical in a window. It takes less time to throw
> the switches than to tune an antenna tuner.
> --
> 73, Cecil http://www.qsl.net/w5dxp
Really, some how or other I got the impression you had to go outside to
change bands. I have some nice open frame DPDT relays that I think would be
great for this. They are more like solenoid actuated knife switches than
what you would normally consider a relay. Actuate one solenoid and the
switch changes. After you deenergize the solenoid the switch stays in the
same state until the other solenoid is energised.
W5DXP
> "W5DXP" <Cecil....@ieee.org> wrote:
>>I control the switches from my shack. They are mounted on a piece of
>>plexiglas sitting vertical in a window. It takes less time to throw
>>the switches than to tune an antenna tuner.
>
> change bands.
The window-line loops are outside but the switches are inside. I've
got a chart on the wall that makes changing bands a snap from the
operating position.
--
73, Cecil http://www.qsl.net/w5dxp
-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
Art Unwin KB9MZ
> aun...@insightbb.com (Art Unwin KB9MZ) wrote in message news:<85ed38d.03072...@posting.google.com>...
> > Seems like a lot of hams with limited resources are still compelled
> > to operate on many bands with just a long wire and a tuner.
> > The wire is inexpensive but the tuners are not. Thus my present
> > project.
> > I was given a Palomar enginnering balun with 5 female connenection
> > which by selection can match a antenna in steps from 5 ohms to over
> > 450 ohms
> > in a series of steps. I am presently rigging it up so that all
> > steps can be switched thru remotely by a single motor. The switching
> > arrangement
>
>
> variable cap, and make a simple L network to feed a random wire. I'd
> rather not use an apple to do a job that an orange should rightfully
> have. :/ MK
Mark,
What sort of range of impedance matching would this provide?
How would you switch bands and what voltage/capacitor range
would be required?
I suspect you would have to have several relays to pick up various
points on the oatmeal inductor as well as a rotation method
for the capacitor
Seems like you have something specific in mind that you would put in a box
for safety reasons. Are the specifics shown somewhere for people to copy?
Art
Dick
I can recall. The first commercial tuner I remember was the Johnson
Viking. Everyone I knew made their own. You just went to the surplus
store, and got a coil and capacitor that looked about right, and tried
it. No one owned any equipment to measure them anyway. We never used
relays. Maybe a switch, or just change the coil. The ARRL handbook
and Antenna Handbooks still have diagrams for antenna tuners. Also
the Hints and Kinks manuals, among many others.
Dick - W6CCD
On 4 Aug 2003 12:51:51 -0700, aun...@insightbb.com (Art Unwin KB9MZ)
wrote:
Dave Shrader
military surplus ARC-5 transmitter for $5 USD and removed the roller
inductor and final plate tuning capacitor. [Actually, I bought 3 ARC-5s:
one for 80, one for 40 both converted to XTAL control, and one for the
tuner and spare 1625s. Nice NOVICE CW rigs.]
Made a real nice L-tuner at 125 watts continuous duty!!
Hmmm .... where are those old ARC-5s when someone needs them??
Deacon Dave, W1MCE
NN...@reno.rmci.net
inverse -square law, temperature decreases at a rate of 1/4 , for every 1/2
of an increment it is removed from you)!
Jim NN7K
NN...@reno.rmci.net
cover/ cap, and rotary inductor into the area of the osc/ magic eye tuneing
tube area-- makes nice package, and considering these tuned from around 160
meters thru 20 (or thereabouts) in different versions, and loaded a aprox 20
foot piece of wire--- make very versatile tuners . also wonder where all
of the bazillions of these dissapeared to! Jim
Richard Clark
Hi Jim,
How close is anything to your flesh when you are holding it? Are you
still holding it, if it were 2 times further away?
Richard Harrison
"also wonder where all those bazillions of these disappeared to!"
I think all the offshore counterfeiters of ARC-5 and 274-N equipment
switched to modern equipment production when demand dwindled for surplus
radios. Too bad!
Best regards, Richard Harrison, KB5WZI
NN...@reno.rmci.net
surface of a balun , (or any other surface, for thatr matter), that by
doubleing the size of the SURFACE, that it would take something like 4 TIMES
as much heat to destroy it. For the same reason that a transistor, in the
size of a micron will vaporize with a slight static discharge , doesn't
necessarily mean that a POWER transistor will even feel a hickup, if it
takes you 30 minutes with a 100 watt soldering iron trying to get solder on
the leads! For the same reason , have 50 ohm coaxial resistor that fits in
a reducer for rg-174, to a SO-239, that would probably crack, with the heat,
and meantime also have a resistor, 1/3 the size, but made to mount on a heat
sink, that will dissipate 100 watts all day! (also made as a 50 ohm load--
same devices, but different uses-- Jim
Richard Clark
>Well, Richard, tho in jest, serves purpose, that even with 30 watts lost on
>surface of a balun , (or any other surface, for thatr matter), that by
>doubleing the size of the SURFACE, that it would take something like 4 TIMES
>as much heat to destroy it.
Hi Jim,
No, this is incorrect. When discussing power dissipation, it follows
a linear relationship to surface area - not square law (you are mixing
radius and surface area arguments). Even letting this pass, power
dissipation does not even conform to doubling with doubling of surface
area. This departure from expectation arises in the increased
distance the heat has to travel to find the surface. This is usually
found in having too many fins in an effort to maximize that same
surface area (and leads to an increase in Thermal Resistance).
Further, more fins also diminish heat transfer through convection
(again increasing Thermal Resistance). 4 or 5 fins is usually
optimal.
Reg Edwards
> > variable cap, and make a simple L network to feed a random wire.
What are the dimensions of an "oatmeal tube carton ?
Are they made of plastic or cardboard?
Here on Euro-side, toilet paper tubes and aligator (crocodile) clips have
been in vogue for many, many years.
Incidentally, my father, a survivor of the trenches, was probably the last
person to make his own variable, air-spaced tuning condensers to be mounted
behind ebonite panels. He drilled panel holes in front of the kitchen coal
fire with an red-hot iron fire poker. All wiring was done with bare square
brass wire. All corners were at angles of exacly 90-degrees. His radios were
Works of Art, appropriately illuminated with a pair of bright-emitter valves
protruding from the top of the cabinet. Circa 1922-30.
So began my early education.
---
Reg G4FGQ.
larry
openned by saying that many hams still use a long wire and tuner. He
comments to say that the long wire is cheap but the tuner is not.
That kinda hit a cord with me because of my antenna experiences. I have
been an amateur since 1964, thats not a brag just a comment. Besides using
a random wire antenna, I have tried multi-band dipoles, quads, beams, folded
dipoles and others. However, I still keep coming back to my old reliable
random wire, about 60ish feet and an L network (the coil connecting to the
transmitter and the capacitor connecting between the ground and the common
connection of the coil and antenna). Though a very simple circuit, it works
very well. Recently I put up a 30ish foot random wire and found that it
didn't work on 80, using the L network. After some thought, I broke the
random wire and inserted a coil. I now gives me a good swr on 80 meters.
I just wanted to defend cheap, but highly functional, antenna couplers and
cheap but useful random wires.
Larry ve3fxq
Sorry if I have come accross a little rough sounding.
"Art Unwin KB9MZ" <aun...@insightbb.com> wrote in message
news:85ed38d.03072...@posting.google.com...
> Seems like a lot of hams with limited resources are still compelled
> to operate on many bands with just a long wire and a tuner.
> The wire is inexpensive but the tuners are not. Thus my present
> project.
> I was given a Palomar enginnering balun with 5 female connenection
> which by selection can match a antenna in steps from 5 ohms to over
> 450 ohms
> in a series of steps. I am presently rigging it up so that all
> steps can be switched thru remotely by a single motor. The switching
> arrangement
MikeN
a Philips 4C6 toroid, around late 70's to match my homebrew helical
mobile whips to my Atlas 210X installed in my Austin 1800 (like a Mini
on steroids and affectionately known as the "land crab").
The separate whips, for 80 40 and 20 metres, could all be matched to
50 ohms, all I had to do when changing bands was to change the whip,
turn the selector switch to the appropriate tapping and away we went.
Best dx - when mobile one afternoon, I heard a VK4 (across the pond
in Aus) calling CQ on 40m, but when I went back to him found he was a
DK4.
MikeN ZL1BNB
bnb
On 29 Jul 2003 08:50:27 -0700, aun...@insightbb.com (Art Unwin KB9MZ)
wrote:
>Seems like a lot of hams with limited resources are still compelled
Art Unwin KB9MZ
Why I chose a switchable transformer is the antenna I use
is always made resonant because of remote variable lumped
constants. ( The loop antenna is a similar type antenna )
Thus for me I only have to deal with RESISTIVE resonant
impedances that vary from frequency to frequency.
The Palomar provides a lot of different ratios between all
inputs and outputs thus SWR of less than 1.3 is really a snap.
As far as efficiency goes I should have defined efficiency but
then it comes down to compared to what.
I suppose a telephone call would be the best no matter how
efficiency is defined. As far as radio goes a remotely switchable
TRANSFORMER placed at the antenna input would be hard to beat
no matter how one defines efficiency.
Now a wag will enter bringing up the subject of inter
coil capacitances in a transformer.
Regards
Art
MikeN <mne...@clear.net.nz> wrote in message news:<jbf8lv8jgcj2lvr9j...@4ax.com>...