Today's Message Index:
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1. 04:45 AM - Re: Terminating Coax Cable to VOR Antenna (Robert L. Nuckolls, III)
2. 04:56 AM - Re: Terminating Coax Cable to VOR Antenna (George, Neal E Capt USAF ACC 505 TRS/DOJ)
3. 05:43 AM - Re: Terminating Coax Cable to VOR Antenna (Eric M. Jones)
4. 05:49 AM - Re: Terminating Coax Cable to VOR Antenna (Mike Welch)
5. 06:08 AM - Re: Terminating Coax Cable to VOR Antenna (Robert L. Nuckolls, III)
6. 06:19 AM - Re: Re: Terminating Coax Cable to VOR Antenna (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: Terminating Coax Cable to VOR Antenna |
At 09:36 PM 5/20/2010, you wrote:
I have a RAMI AV-12 VOR antenna that has the two machine screws/studs
for electrical connection to the coax cable -- it doesn't take a BNC
twist-on connector. I believe the coax that I have is a double
shielded type but it isn't RG400 -- it has a bright yellow outer jacket.
How did you acquire the ooax? Did it come with the
antenna as a kit?
How do I terminate this coax cable to this antenna? Do I just crimp
PIDG terminals (or solder suitable lugs?) to the braided shield and
to the center conductor?
Yes, make the lengths of these leads as short as practical.
I'd also use some heat-shrinked tubing. Is anything more than this required?
Nope.
Bob . . .
Message 2
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| Subject: | Terminating Coax Cable to VOR Antenna |
Bob -
Connectors appropriate to the antenna's lugs, either crimped or soldered
will do just fine. Keep the length of exposed center conductor to a
minimum. Support the cable with a clamp very near the end of the jacket,
fastened to the airframe to provide strain relief and vibration protection.
Neal
====================
How do I terminate this coax cable to this antenna? Do I just crimp PIDG
terminals (or solder suitable lugs?) to the braided shield and to the center
conductor? I'd also use some heat-shrinked tubing. Is anything more than
this required?
Best regards,
Bob Falstad
GlaStar N248BF
310 Hours in two years
Message 3
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| Subject: | Re: Terminating Coax Cable to VOR Antenna |
For frequencies near or above 1 MHz, coaxial cables are best terminated with a
connection method that is easy to make or buy that avoids the unnecessary losses
in pigtailing the shield.
Yes, you can "get away with" pigtails, but Google "Kimmel Gerke pigtails" and learn
how to do this important task....
And see my "Dabbling with Electricity...It's Child's Play" attached for more explanation.
(I have also attached for your pleasure the Popular Mechanics 1943
Army Test.)
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones@charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=298415#298415
Attachments:
http://forums.matronics.com//files/army_test_173.pdf
http://forums.matronics.com//files/dabbling_with_electricity_994.pdf
Message 4
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| Subject: | Terminating Coax Cable to VOR Antenna |
> How did you acquire the coax? Did it come with the
> antenna as a kit?
> Bob . . .
Bob=2C
Yes=2C it does. One of the two experimental planes I'm building is a Gl
aStar. When ordering some of their options=2C I got the dipole com radio a
ntenna kit. Evidently=2C whoever they have build their antennas likes to u
se this triax cable.
I got the com antenna fastened to the inside of the vertical stabilizer
=2C and glued the two halves of the plane together. I forgot to look at ho
w they handle the antenna end of the cable=2C that's why I asked previously
about the balun information.
In the present topic=2C do I understand correctly that you combine the in
ner and outer shields together on the solder lug=2C at the antenna end?
Mike Welch
_________________________________________________________________
The New Busy is not the too busy. Combine all your e-mail accounts with Hot
mail.
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ID28326::T:WLMTAGL:ON:WL:en-US:WM_HMP:042010_4
Message 5
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| Subject: | Terminating Coax Cable to VOR Antenna |
At 07:46 AM 5/21/2010, you wrote:
> How did you acquire the coax? Did it come with the
> antenna as a kit?
> Bob . . .
Bob,
Yes, it does. One of the two experimental planes I'm building is
a GlaStar. When ordering some of their options, I got the dipole com
radio antenna kit. Evidently, whoever they have build their antennas
likes to use this triax cable.
Just making sure it wasn't some form of ohterwise
un-identified cable . . .
I got the com antenna fastened to the inside of the vertical
stabilizer, and glued the two halves of the plane together. I forgot
to look at how they handle the antenna end of the cable, that's why I
asked previously about the balun information.
Adding the balun is a technically satisfying thing
to do for this style antenna but will offer no
observable improvement in your VOR system performance.
In the present topic, do I under stand correctly that you combine
the inner and outer shields together on the solder lug, at the antenna end?
Yes, you can do that. But if you do the elegant
breakout of the center conductor through the shields
like . . .
http://aeroelectric.com/articles/shldwire/shldwire.html
. . . you'll find that the bulk of strand for
two sets of shields demand a rather hunky
PIDG terminal. This is an exceedingly non-critical
application that doesn't really benefit from
double-shielding. At the antenna end, you can
simply cut away all of the outer shield at the
outer jacket and terminate only the inner shield
as suggested above.
Bob . . .
Message 6
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| Subject: | Re: Terminating Coax Cable to VOR Antenna |
At 07:41 AM 5/21/2010, you wrote:
>
>For frequencies near or above 1 MHz, coaxial cables are best
>terminated with a connection method that is easy to make or buy that
>avoids the unnecessary losses in pigtailing the shield.
>
>Yes, you can "get away with" pigtails, but Google "Kimmel Gerke
>pigtails" and learn how to do this important task....
In this case, we're making a transition between a coaxial
feed line and pieces of metal intended to be exceedingly
NON-coaxial, I.e. elements of an antenna.
Pig-tails on the end of the coax simply become part
of the total length of each antenna element. The
existence or non-existence of a constant impedance
connector at the end of the coax is not a factor
for over-all performance. The technically elegant
design will shorten the elements by the same dimension
added by the pigtails. This adjustment for length
will produce a more satisfying SWR plot over the
range of interest . . . but it's not going to
make an observable difference in system performance.
In this instance, doing the PIDG-on-pig-tails
termination provides a more robust, lower parts-
count transition between the feed line and the
antenna elements without degrading performance.
If one opted for a pristine connector, then
a mating connector needs to be part of the
antenna assembly. The same pig-tails from
the mating connector to each antenna element
will exist and have the same influence on the
antenna's resonant frequency. Parts count and
numbers of connections go up.
The K&G admonitions for preserving feed-line
integrity are quite accurate but not applicable
in this instance.
Bob . . .
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