Antenna, Antenna Bases

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Antenna, Antenna Bases

Post by rmel » Sun Jan 24, 2016 10:39 pm

I often get questions about my Antenna and Antenna bases on my 710K. These are a combination of Military and
commercially available antenna and mounts — providing a broad range of HAM bands and CB. This took some research,
so I thought I’d share that here for those interested in Emcom or just truck-to-truck communication.

For CB, I use a Breedlove quick disconnect Brass Mount, Mounted in the existing
chassis hole on the drivers side just below the windshield hinge. With a 2’ K40 whip I get decent short range and avoid weed
whacking, for longer range I use a 4’ K40. Use of an antenna spring between base and antenna to avoid antenna damage and
minimize flexing the chassis. The Radio is mounted behind the drivers seat. I prefer compact units such as the Cobra C75 WX ST,
which has all the controls in the Mic — very handy.
CD-AntMount.jpg (16.69 KiB) Viewed 1317 times
The other possibility for CB is the existing Pinz Mount with a military base (4.5” BHC) and whip. The best choice is the MX-6707,
the original Pinz base.
MX-6707-1.jpg (12.26 KiB) Viewed 1317 times
The whip is a two section center feed vertical dipole and is very efficient for the bands it was designed for; 30MhZ to 75Mhz. For mobile
applications a vertical dipole is a very good choice for high clearance vehicles which results in poor ground reference. The base is a
matching unit with 10 sub-bands from 30-33, 33-37…up to 75Mhz — remotely selected by the RT-524A radios via a 12-pin cable, or
manually with a switch on the base. The closest band for CB is 30-33MhZ which is far enough outside the CB band to not perform well
unless tuned to the lower CB frequency. This is easy to do by adjusting a tunable capacitor (C8) in the base, ... nna_cb.htm. The next generation radio system SINCGARS common in
Humvee uses the AS-3900A base. This system is not tunable, and will not perform as well for CB as a tuned MX-6707. The AS-3900
was designed for Frequency hoping (Spread Spectrum) over broad-band, the compromise is that performance at fixed frequencies will be
fair to poor depending upon the frequency.

The Military base I selected for HF HAM is the Shakespeare Model 120 System with the 4245 base. This base is a feed-through,
no tuning components. The 4245 is very beefy but fits on the Pinz mount. The antenna AT-1011, comes in 4' sections to a max of 32'.
A tuner back at the radio adds flexibility avoiding adding 4’ sections for band changes. I typically operate on 20M with 16' stationary
and 8’ Mobile. These components are getting harder to find on the Surplus market. I was lucky to find a unused 4245 base and a
number of sections from Murphy’s Surplus Shakespeare will sell New to consumers but pricey.
American Mil Spec has some limited number of sections as well.
Mount+Base.jpg (47.15 KiB) Viewed 1317 times
AT-1011.jpg (89.94 KiB) Viewed 1317 times
For VHF/UFH I use a “NMO” New Motorola mount. These mounts are large thread diameter 1 1/8” - 8 tpi, brass, durable, easy
removal. I use a 40” Comet broadband CA-2x4SRNMO antenna which is excellent for 2M/70cm HAM as well as GMRS/FRS
communication. I mounted this to my Solar panel base.
RoofView.jpg (18.5 KiB) Viewed 1317 times
With the above, I have reasonably robust communications, supporting short range and up to 1,000+ miles, Voice, Digital, APRS,
and eMail via the Winlink system.
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712M

Driver: Ron // KO0Q

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Re: Antenna, Antenna Bases

Post by GadgetPhreak » Sat Mar 05, 2016 12:15 pm

Awesome setup, thanks for sharing! I'm building out my rig for Search and Rescue use and have started thinking about my antenna configuration. On my Jeep I had 4 of the diamond antenna motors that all raised/lowered with one switch. It worked well when going under low branches or into a garage. I will be running two Icom VHF, one Icom UHF and one Yaesu Dual band HAM. I didn't run CB in the Jeep at all and only wished I had one once over 8yrs so unlikely to add one here either.

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King County Search & Rescue | Regional Special Vehicles Unit
1972 710M - Building up for SAR use
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