Military Vehicles, June 1997,: Re: [MV] Radio help (long)

Re: [MV] Radio help (long)

Mark J. Blair (
Mon, 23 Jun 1997 23:20:14 -0700

Robert Ratliff <> wrote:

> However, in my defense, the sergeant who taught me radios and electronics
> told me the RT-524 was the vehicle version (and/or a component thereof) of
> the PRC-25/77 series.
> As I am not in the military (I took the class because of an emergency reponse
> requirement - we had to know how to use military equipment such as radios in
> case of a disaster), I don't have the access which you do. Also, I am going
> off what I was told at the time.

Well, your sergeant was mistaken. I'm not in the military, either, but
I collect and restore US military radios, and I have the Army
maintenance manuals for the VRC-12 series, its major components, and
some of the maintenance manuals for various systems which include the
PRC-27/77 (these are NOT part of the VRC-12 series). I've also run
into many of these radios and systems while shopping, although I don't
own any... yet... (most of my current radios are from the previous
generation of vehicular sets). I think I can set the record straight
on this thread, since I have the real Army manuals for these radios,
with pictures, sitting right here on my desk.

> In any case, that's my defense.

No need to feel defensive! I can't remember this junk without looking
in the manuals, and this junk is my favorite hobby! I just wanted to
end all of the confusion in this thread.

Well, here goes:

The RT-524 is a vehicular transceiver which is used in half of the
VRC-12 series sets. It covers 30.00 to 75.95 MHz in 50 kHz steps, and
delivers at least 35 watts on high power. It's mostly solid-state, but
uses a tube-type power amplifier. It's not a PRC-25 or PRC-77, it
doesn't have a PRC-25 or PRC-77 inside it, and it doesn't look
anything like a PRC-25 or PRC-77. I'd love to include the pictures so
everybody can see what this radio looks like, but I don't have access
to a scanner. Also, my manuals don't list the dimensions or weight (or
I haven't found them... the manual stack is about a foot tall!), so I
can't quote those accurately. From memory, it's around 8" tall, 18" or
so wide, and maybe 12-14" deep. The PRC-25/77 with its vehicular power
supply/amplifier mounts in the same mounting as the RT-524. The RT-524
is just one big piece, though. It doesn't break down into a backpack
rig and a power supply/amplifier like the vehicular PRC-25/77
installations do.

The RT-246 is similar to the RT-524, but allows the user to program 10
preset frequencies, and select them with pushbutton tuning. It also
lacks the built-in speaker that the RT-524 has. The box is the same
size, its specifications are the same, and it plugs into the same
mount, but its front panel looks different.

There are also RT-524A and RT-246A radios, which can be used
interchangeably with their non-A counterparts.

The R-442 is an auxiliary receiver that is used along with the RT-246
or RT-524 in many of the VRC-12 series sets. It's the same height and
depth as the RT-524, but is about 6" or so wide (from memory).

Here is a brief summary of the VRC-12 series sets, with their major
components listed (I'll omit listing mounts, antennas, cables, etc.,
and just list the major radios in the sets):

Radio Set Major Components
AN/VRC-12 RT-246, R-442
AN/VRC-43 RT-246
AN/VRC-44 RT-246, R-442 (x2)
AN/VRC-45 RT-246 (x2)
AN/VRC-46 RT-524
AN/VRC-47 RT-524, R-442
AN/VRC-48 RT-524, R-442 (x2)
AN/VRC-49 RT-524 (x2)

Now, on to the PRC-25 and PRC-77 sets:

The RT-505/PRC-25 is a short-range radio used in either a backpack
configuration (AN/PRC-25) or vehicular configuration (AN/VRC-53),
operating in the same band as the VRC-12 series, and capable of
communicating with them. It's mostly solid-state, with one tube in the
power amplifier.

The RT-841/PRC-77 is a newer version of the RT-505/PRC-25, and is all
solid-state. It looks just like the PRC-25. It is "functionally,
operationally and in appearance identical to" (quote from the tech
manual) the RT-505/PRC-25, except that it has "X-mode" capability,
which the RT-505/PRC-25 lacks (I think this is a mode used with
external scrambling/encryption equipment; somebody correct me if I'm

The OA-3633 group is an amplifier/power supply and cable which is used
in vehicular installations of the RT-505 and RT-841. It consists of an
AM-2060/GRC amplifier/power supply and a CX-4655/GRC cable. Yes, they
had to some up with a special number just to keep track of the power
supply *with* the 8" cable. This stuff gives me a headache. Anyway,
The transceiver clamps into the AM-2060, the CX-4655 connects between
the two, and then the AM-2060 clamps into the vehicular mount (which
happens to be the same mount used in the VRC-12 series, which probably
caused some of the confusion in this thread!).

Now, here are the various complete sets:

AN/PRC-25: An RT-505, with necessary accessories, strapped on some
poor grunt's back.

AN/PRC-77: An RT-841, with necessary accessories, strapped on some
poor grunt's back.

AN/VRC-53: The vehicular installation of the RT-505, with an OA-3633.

AN/VRC-64: The vehicular installation of the RT-841, with an OA-3633.

AN/GRC-125: This is basically an AN/VRC-53, but also includes extra
accessories so that you can pull the RT-505 out of the mount and
configure it as an AN/PRC-25 (that is, it includes the extra stuff you
need in order to use the radio in its backpack configuration).

AN/GRC-160: This is basically an AN/VRC-64, but also includes extra
accessories so that you can pull the RT-841 out of the mount and
configure it as an AN/PRC-77 (that is, it includes the extra stuff you
need in order to use the radio in its backpack configuration).

Note that the "PRC-25" refers to the complete backpack configuration,
and is not the correct name of the transceiver by itself, so it's not
really correct to refer to a "vehicular PRC-25". However, most people
commonly call the RT-505 and anything that has one it it a "PRC-25",
and I do that myself, even within this message. The same comments
apply to the RT-841 and the PRC-77.

> The complete vehicle version of the PRC-25/77 series is know as the VRC-12
> series. This consists of two PRC-25/77's, their vehicle amplifers (AM-5040 I
> think), their vehicle mounting brackets, all the interconnecting cables,
> their transmitting and receiving antennas with matching units, etc.


I don't know what an AM-5040 is. It's not listed in my
AN/VRC-53/etc. manual, but my manual is dated 1967, so maybe the
AM-5040 is a newer version of the AM-2060. I dunno.

I'll provide tech. manual titles, numbers and dates if anybody really

I hope this answers everybody's questions. I also hope that I haven't
just started a "stop talking about radios in the vehicle list"
flamefest. :-)

Mark J. Blair  KE6MYK

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