Re: [MV] MV Antenna

From: Richard Notton (Richard@fv623.demon.co.uk)
Date: Fri Dec 31 1999 - 01:54:06 PST


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-----Original Message-----
From: jim gilmore <jgilmore@oeonline.com>
To: Military Vehicles List <mil-veh@uller.skylee.com>
Date: 30 December 1999 21:07
Subject: Re: [MV] MV Antenna

> I think you will find the length (height) of the antenna on a MV depends on
the radio fitted. The antenna is "tuned" to the frequency of the radio set. For
example; A U.S. RT-68 radio uses a shorter 2 section antenna than the 3
section one on a RT-66 or RT-67 radio even though the RT's look identical. It
is the difference in the band width that determines the antenna sections used.
RT-68 (38 to 54.9 mc.) uses 1 MS-117-A and 1 AB-24-GR antenna sections. RT-66
(20 to 27.9mc) and RT-67 (27 to 38.9mc) radios use 1 MS-116-A, 1 MS-117-A and 1
MS-118-A sections.
>
The UK antennas are abundant except the bottom section that has the plain end to
fit the base, these are invariably broken by the mil and never make the surplus
market. The rolled thread of the next section does perfectly fit the base
though and is a common sight here, operation of the radio itself is rare owing
to law here though.

These MS 116/117/118 sections are virtually identical though and handy for those
Americans with anything from a Ferret to a Centurion. These were going cheap at
Beltring last year and unused too with little interest from the punters. In
actual fact you can saw off the thread on the MS-116A or MS-117A section and the
generous length of swaged-in copper plated plain tube left is a perfect fit in
the UK antenna base, again the rolled thread will push-fit the base too. By
this means you can make a two section nominal 6' antenna or a 9' with all three.

> The RT-66 is used by armor units, the RT-67 by artillery units and the
RT-68 by the infantry.
>
> The British/Canadian radios such as the C-42, C-45, C-12 and No. 19 sets
will also have their antenna "tuned" to the frequency of the particular set.
>
Generally the UK mil radios will actually load into almost anything, in some
applications an additional base tuner is used. The 19 set with its variometer
is certainly capable of loading almost anything from a 4' whip to a long wire,
with loading unit No.1, (basically a 140pf cap to ground) a 6" antenna is used
for command vehicles in close proximity.

> If you plan to actually use your radio, it is important to make sure you
are using the correct antenna, not just one that "looks cool". Never, never,
transmit on your RT without having an antenna hooked up as you WILL burn out
your transmitter. And don't hold on to the antenna when transmitting.....could
be quite shocking!
>
Heed this warning, although these older HF sets often only make a watt or two of
RF power, certain places on the antenna will have exceedingly high voltages on
them. An RF burn is deep and nasty as it is the deep skin burn you feel before
any electrical shock, I have two 40yr old knuckle mounted scars to prove it,
courtesy of a Mk III 19set.

Richard
(Southampton UK)

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