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Old June 24th 13, 01:57 PM posted to rec.radio.amateur.antenna
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First recorded activity by RadioBanter: Jun 2013
Posts: 1
Default Help with commercial VHF mobile antenna



It's a long story, here's the short version.

Our volunteer rescue squad dispatch operates in the 152 - 154 MHz
range -- transmit on 154.XXX, receive 152.XXX.

Our main antenna barely survived contact with a tree limb and needs to
be replaced.

Our local Motorola sales rep has his head stuck firmly up his ass and
keeps trying to sell us some basic 1/4-wave verticals.

The current antenna is a vertical whip with a loading coil wound
along the length of the antenna.

The dimensions a

-- Overall height: 14.25 inches
-- 4 inches from the base the antenna is wound into a coil, about 3/8
inch diameter, 5 turns
-- the coil is 1.75 inches long
-- above the coil is 8.5 inches of antenna
-- NMO base

I suspect this antenna is an old model 5/8-wave VHF antenna, shortened
by winding a coil in the antenna.

If it is a 5.8-wave, it should be giving us a few dB gain. The
1/4-wave whip he wants me to install would give unity or less gain. In
our rural area, we need all the antenna help we can get. I an
thinking about installing a full-length 5/8-wave whip, but, we go into
a lot of driveways with low tree limbs and I doubt a full-length
antenna would survive very long.


I have Googled every term I can think of to find this antenna,
Motorola sales rep tells me he thinks its a "cellular antenna" . .
..which it clearly is not. My MFJ antenna analyzer shows a resonance
at 154 MHz.

Anyone help me identify this antenna?


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