On Fri, 11 Sep 2009, Mike Morris WA6ILQ wrote:
> I've been thinking about setting one up, as a future project is to set
> up a mobile, either a low band Syntor-X9000 or a Maratrac, with some
> channels on Red Cross and the rest on amateur 6m. I may have to go to
> a screwdriver antenna as a 1mh
Milt said:
> The
> chart in the document was developed specifically for the
> Spectrum series
> series fed LB antenna. THE MEASUREMENTS IN THE CHART WILL NOT
> WORK WITH
> SHUNT FED COILS!
So as I guessed, the secret sauce is the type of antenna/loading coil used.
It might be a worthwhile ex
Steve,
The document in question is on the repeater-builder WEB site, not the files
area for this group.
There were two documents produced by Motorola , each dealing with specific
antenna combinations allowing the use of 2 antennas to cover areas of VHF
lowband. One dealt with using two Motor
> Being an analytical guy I modeled the antenna system in both
> Ansoft Designer and an antenna modeling program. In Ansoft
> Designer the antennas were modeled as a series RLC load with
> 50 ohms at resonance and a Q of 15. Transmission lines were
> modeled with VF equal to that of RG-58A/U co
Re: [Repeater-Builder] Diplex antenna installation using
coaxial cable for 10M and 6 M
At 05:32 PM 09/11/09, Joe, K1ike wrote:
>The average coax cable of 1985 vintage probably had a velocity factor of
>66%. If you didn't figure this into your calculations the coax would
>appear to be
Mike-
How about using an automatic antenna tuner with a whip 6 foot whip?
-- Original Message --
Received: Fri, 11 Sep 2009 10:50:49 PM PDT
From: Mike Morris WA6ILQ
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] Diplex antenna installation using coaxial
cable for
At 05:32 PM 09/11/09, Joe, K1ike wrote:
>The average coax cable of 1985 vintage probably had a velocity factor of
>66%. If you didn't figure this into your calculations the coax would
>appear to be about 1/4 physical length, but would be an electrical 1/2
>wavelength. Did you use a velocity facto
I did take into account the velocity factor in the simulations.
In Ansoft Designer I can specify physical length and VF.
In the antenna simulator I am currently using I cannot specify the VF so VF
= 1 and
I use coax lengths equal to free space wavelengths.
The document was given to me in PDF forma
It is on the repeater builder website already.
-- Original Message --
Received: Fri, 11 Sep 2009 05:32:31 PM PDT
From: Joe
SNIP
> Would it be possible to scan the Motorola document that you have and
> post it to the group? I've heard of it but I've never seen it.
The average coax cable of 1985 vintage probably had a velocity factor of
66%. If you didn't figure this into your calculations the coax would
appear to be about 1/4 physical length, but would be an electrical 1/2
wavelength. Did you use a velocity factor in your calculations?
Would it be poss
--- On Fri, 9/11/09, Steven Schultz wrote:
From: Steven Schultz
Subject: Re: [Repeater-Builder] Diplex antenna installation using coaxial cable
for 10M and 6 M
To: Repeater-Builder@yahoogroups.com
Date: Friday, September 11, 2009, 5:29 PM
Thanks Mark and John for your response
Thanks Mark and John for your response.
I can appreciate using the Comet CF-360B duplexer as a quick solution,
John. Thanks.
Mark, I can also see the matching bandwidth being better with shorter
transmission line.
But my concern is that 1/4 wavelength transmission line sections seem to
be very i
I did this same thing but went about it by a different direction.
I mounted the 52 mhz antenna and the 29 mhz antenna on the roof of
my Ford Explorer. I ran the coaxes down and connected them both to a
Comet 10meter/6meter diplexer and plugged the common end of the diplexer
into my radio.
Look
Steve,
The shorter length stub most likely will give you wider matching
bandwidth... This may be why Motorola spec'd a 1/4λ stub as opposed to a
1/2λ stub, as well as nominally lower costs for the shorter cable length.
Maybe this will help explain my reasoning:
http://www.ittc.ku.edu/~jstiles/723
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