RG-8 vs. RG-213?
Jerry Bransford
HF antenna, discovered a new cable type being recommended here and there,
RG-213. What is so much better about RG-213 than what I have used so much
of over the years, RG-8? TIA. :)
Jerry
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Jerry Bransford
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VHFRadioBuff
>HF antenna, discovered a new cable type being recommended here and there,
>RG-213. What is so much better about RG-213 than what I have used so much
>of over the years, RG-8?
RG-213 has less loss per 100 ft than RG-8. Nothing too significant though, not
at HF freq's at least. Check out:
http://www.radio-ware.com/products/techinfo/coaxloss.htm
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
73! de Andy KC2SSB - WPYI880 (GMRS)
Beachwood, NJ USA! Grid FM29vw
http://vhfradiobuff.tripod.com
p.paulf...@comcast.net
news:20031208092607...@mb-m21.aol.com...
I think you are comparing RG-8X (the mini stuff) to RG-213. RG-8U has lower
lose than 213.
Sorry, I don't mean to be pedantic, but as a new ham myself, I found the
various 8s confusing.
73
Paul AB0SI
Jerry Bransford
loss per foot than RG-8 did. Somewhere I got a feeling that perhaps
RG-213's strength was that it was longer lasting but even that doesn't make
sense for several reasons. I've even noticed antenna kits that include
RG-213 so maybe its just less expensive and they can make higher profits
with RG-213 than they can with RG-8 at the expense of slightly higher loss?
Jerry
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Jerry Bransford
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"paulfr...@comcast.net" <p.paulf...@comcast.net> wrote in message
news:w20Bb.461703$HS4.3603203@attbi_s01...
p.paulf...@comcast.net
Off the subject, but....
Last week I had an interesting QSO with a gentleman who runs nothing but
hard line -- and SERIOUS hardline at that. His jumpers are LHR 600 -- he
uses lower loss stuff (honest) for his runs. This includes the runs for his
160m and 80m antennas. Now, there is a person who does not like loss.
Paul AB0SI
"Jerry Bransford" <jer...@mecox.net> wrote in message
news:je0Bb.30145$Bk1.26174@fed1read05...
John Passaneau
RG-8 used to be a military specification cable but the military dropped it
in favor of a new specification called RG-213. They are very similar coaxes
in general, but manufactures are free to make any cable they like and call
it RG-8 so the quality and consistency can vary widely. Also RG-8 with foam
a center insulator, and all the other variations are not nor never were
MilSpec.That does not mean that all RG-8 cables are crap, but it could be
and it depends on the manufactures idea of what kind of cable they want to
sell. On the other hand RG-213 as a current MilSpec cable is a higher grade
cable and is more consistent from manufacture to manufacture. My feeling is
that if I'm going to go to all the work of installing a antenna, I want to
use the best material I can. So I use RG-213. But my favorite coax is Davis
RF Bury Flex, http://www.davisrf.com/ . It's a good coax that has low loss
and a very tough jacket. I have 500 feet of it in my antenna system and so
far I'm very happy.
--
John Passaneau W3JXP
State College Pa
jx...@psu.edu
This mail is a natural product. The slight variations in spelling and
grammar enhance its individual character and beauty and in no way are to
be considered flaws or defects.
"Jerry Bransford" <jer...@mecox.net> wrote in message
news:moUAb.29779$Bk1.25134@fed1read05...
Jerry Bransford
Thank you very much John.
Jerry
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Jerry Bransford
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"John Passaneau" <jx...@psu.edu> wrote in message
news:br24ah$1j7e$1...@f04n12.cac.psu.edu...
VHFRadioBuff
>lose than 213.
According to the webpage that I referenced, the differences are as follows:
RG-8X: 0.5dB at 1mhz
1.0 dB at 10mhz
RG-213: 0.2dB at 1mhz
0.6db at 10mhz
The original poster asked about RG-8. No reference to either X or U.
Bob Miller
<jer...@mecox.net> wrote:
>THERE'S the answer I was looking for and it all now makes perfect sense.
>Thank you very much John.
>
>Jerry
Not to confuse/clarify matters more, but try the coax chart at
http://thewireman.com/coaxp.html
They have five kinds of rg-8 and four kinds of 213. The rg-8s all show
less loss than the 213s.
Guess it all depends on who's manufacturing the stuff.
Bob
k5qwg
Uncle Peter
"VHFRadioBuff" <vhfrad...@aol.comspamme> wrote in message
> >I think you are comparing RG-8X (the mini stuff) to RG-213. RG-8U has
lower
> >lose than 213.
>
> According to the webpage that I referenced, the differences are as
follows:
>
> RG-8X: 0.5dB at 1mhz
> 1.0 dB at 10mhz
>
> RG-213: 0.2dB at 1mhz
> 0.6db at 10mhz
>
> The original poster asked about RG-8. No reference to either X or U.
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
I think most would assume he meant for similarly sized cables.
Steve Nosko
and brains.
Steve K<9;D:C:I
"paulfr...@comcast.net" <p.paulf...@comcast.net> wrote in message
news:as0Bb.469926$Fm2.459011@attbi_s04...
J. McLaughlin
frequencies. Mac N8TT
--
J. Mc Laughlin - Michigan USA
Home: J...@Power-Net.Net
"John Passaneau" <jx...@psu.edu>
<snip>
Tom Bruhns
US military at all. Mil-C-17 now??--and I'm not sure any current ones
are polyethylene (and not Teflon) dielectric. As John points out, RG
numbers have been somewhat corrupted! But in general, "RG-213/U" and
"RG-8/U" should both be solid-polyethylene dielectric cables with the
same diameter and the same stranded inner conductor and single copper
braid outer, and therefore should have the same attenuation per unit
length, nominally. There will be minor variations from lot to lot, or
larger variations if the coax was made poorly. "Reference Data for
Radio Engineers" says of RG-213, "Formerly RG-8A/U."
Foam dielectric cables, perhaps called "RG-213-type" or "RG-8-type,"
have lower loss for a given outer conductor diameter because the inner
conductor is larger diameter and therefore has less resistance than
with solid dielectric. (Similarly for Belden 9913-type cables.) But
they may not be able to handle as much power, because the foam
dielectric may be enough better a thermal insulator that the inner
conductor still gets as hot or hotter at a given power, and that's the
limitation. Also, you should be careful with bends in foam dielectric
cables, because they can cause the center conductor to go off-center;
that's especially bad if the cable's used at VHF/UHF. There's plenty
more about the subject, but hope this helps a bit.
Cheers,
Tom
"John Passaneau" <jx...@psu.edu> wrote in message news:<br24ah$1j7e$1...@f04n12.cac.psu.edu>...
Jerry Bransford
Jerry
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"Tom Bruhns" <k7...@aol.com> wrote in message
news:3200347.03120...@posting.google.com...
Scott
It was installed in the KC, EC and RC-135's I worked on in the Air Force in
the 80's. The planes were built in 1955 through about 1964 that I worked
on. One day we had a transmit problem on our UHF radio (225-399.975 MHz
AM). 10 Watts out, 10 Watts reflected. That's bad. We put a TDR on the
line and saw an impedance discontinuity about 30 feet downstream from the
transmitter. After pulling several floor panels and sending our only (tiny)
female Tech Sargeant head-first down the floorboards, we had her disconnect
the coax clamps and removed the coax. Cut it open and found the center
conductor had migrated through the inner insulation allowing contact with
the shield. The defective area was on a horizontal run. Not sure if
gravity or vibration over 30 some years was at work or maybe fuel fumes
deteriorated the stuff, softening it. I guess I suspected fumes because not
long after that, we had a KC-135 blow up at Altus AFB in Oklahoma. Cause
was determined to be a loose N-Connector at the antenna and when the radio
keyed up there was a spark as the RF jumped the gap and boom. Cinders on
the runway.
Scott
N0EDV
"Tom Bruhns" <k7...@aol.com> wrote in message
news:3200347.03120...@posting.google.com...
Crazy George
current copy of MIL-C-17. Throw away your MIL-C-17E or earlier. Cables
nomenclatured simply RG-nnn/U haven't been supported by the DOD system for
well over 20 years. Only M17/+++-RGNNN nomenclatured cables are truly
MIL-SPEC. See below.
Jerry: Here is a very condensed history of coaxial cable nomenclature.
Now, in the beginning, coax impedances resulted from standard size wires and
tubing. RG-8/U was 52 ohms, which resulted from the dimensions which were
quickly attainable in wire manufacturing in the 1930s. RG-8A/U was the
same, except the jacket was made from a plastic which did not contaminate
the dielectric through migration of the plasticizer. I recently had access
to some old Federal Radio and Telephone Labs records which contained quite a
discussion on dielectrics and jackets. Plastic technology was pretty
primitive back then. So was wire manufacturing, and braid overlaying.
In the 1960s all common coaxes were normalized to round number impedances
and issued new nomenclature, RG-8/U at 52 ohms becoming RG-213/U at 50.0
ohms. RG-9/U became RG-214/U, and so on ad naseum. RG-11/U was already
exactly 75 ohms, so it remained the same (and then moved on to M17/6-RG11).
RG-13/U, on the other hand, the double shielded half inch 74 ohm coax became
RG-216/U at 75 ohms. The new numbered cables were, for all practical
purposes, the same as their predecessors, except for the impedance. 50.000
ohm network analyzers were now safe.
Then in the 70s came cable TV and other wideband systems, which encountered
performance problems due to unpredictable phase characteristics across the
frequency range. This was found to be typically caused by repetitive
mechanical disturbances in the cable construction. To fully qualify the
cables, swept frequency performance measurements were added to MIL-C-17E,
and the nomenclature changed yet again to the present M17/+++. Now, you
don't see much of this 'new' M17/+++ stuff in ham use because it is another
increment more expensive, and hams typically don't have requirements for
wideband, predictable phase characteristics anyway. But, RG-213/U, which we
had just gotten used to then became M17/163-00001, the cheaper non-swept
direct equivalent, or M17/74-RG213 for the more expensive version swept from
50 MHz to 1 GHz. And cable bearing that nomenclature better meet the
specifications of the current MIL-C-17.
Now, just to be clear, there is no rule anywhere against anyone with cable
manufacturing facilities making coax of any kind and quality (or even rope
or water hose for that matter), and labeling it RG-8, or RG-213, or
RG-(anything else). So asking about RG-8 (or RG-213) is like asking what
the impedance of a wet noodle is.
Finally, a quote from the MIL-C-17 page in the Times Fiber RF Transmission
Line Handbook pretty well summarizes it, even better than the specification
itself. Especially the last sentence:
"Cables that are manufactured to MIL-C-17 specification no longer carry the
RG designation. Instead, they are marked with an M17 designation. For
example, RG-214 has been replaced by M17/75--RG214. In the future, any new
cable design will be designated by a M17 number only.
"In addition to the M17 number, all cables are marked with the
manufacturer's name and government identification number, for example,
'M17/75-RG214, MIL-C-17, Times Fiber Communications, 68999, AA-3409.'
Cables that are not marked with all this information are not qualified and
there is no guarantee of their performance."
--
Crazy George
VHFRadioBuff
Since I don't know the physical differences between RG-8, RG-8U, RG-8X and
RG-213, I wouldn't know that he meant similarly sized cables.
Jerry Bransford
electronics whiz to my friends and neighbors but I feel like a beginner
here. Thanks again! :)
Jerry
--
Jerry Bransford
To email, remove 'me' from my email address
KC6TAY, PP-ASEL
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"Crazy George" <muNn...@attSglPobaAl.nMet> wrote in message
news:3fd54...@news1.prserv.net...
JDer8745
I personally like RG-214 but it's very expensive, at least as far as I'm
concerned,
I only have a small amount I have gotten at hamfests.
75-Ohm TV hardline is available from your TV cable company as reel ends usually
for free.
The last I got had 134 feet left on the reel and was insulated and 1/2 inch in
diameter. But there is a price problem with connectors. Many hams fabricate
their own. TV cable companies don't give connectors away.
73 de Jack, K9CUN
Dan/W4NTI
"VHFRadioBuff" <vhfrad...@aol.comspamme> wrote in message
This is what I like about Andy...VHF Radio goof. He knows nothing but that
don't stop him from giving his 'advise'.
A MAJOR factor for using 213 is it is Mil-spec.
And it sure isn't new cable.
Dan/W4NTI