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Armor/AFV: Modern - USA
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M151A2 Radios and Antennas
Burik
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Posted: Thursday, January 05, 2017 - 06:38 PM UTC
So I am doing a Grenada jeep, 1983. I am confused with how to wire up the radios and what antennas to use.

My idea is to have radios on both sides of the jeep, not just the basic one. I do not want to do a gun jeep. So I THINK I would be using all three of these radios from the old Verlinden set. Do es that mean I have to use three antennas? Or does the RT-442 share an antenna?

On the third pic note the extra antenna on the side of the vehicle. Is that for a specific radio only? That antenna is different than the typical antenna.

Also, the wiring has me confused. I think I can figure out based on diagrams and pics where to hook up the antenna and how the wire looks for that. But what about the wire on the left side of the attached second photo? Where is that going? To the engine battery? A hole in the body? I assume the batteries have to be wired to something for power.

The more I google the more I am confused.





Frenchy
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Posted: Thursday, January 05, 2017 - 07:29 PM UTC
According to this thread :

http://g838.org/viewtopic.php?f=5&t=3789

the side antenna is a AB-15 one (used with the R-442)...

H.P.
HeavyArty
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Posted: Thursday, January 05, 2017 - 07:40 PM UTC
Each radio has its own antenna. So the vehicle you have pictured has three antennas, hence three radios (as in the Verlinden set). It is most likely a commander or staff officer vehicle. The smaller antenna on the side is for the RT-442. You can see the RT-442 on that side of the vehicle next to the other radio set (toward the rear).

On the RT-524, the wires across the bottom are, from left to right; handset, speaker, and power (one w/the metal 90 degree connector). The power cable runs under (or next to) the radio mount and down the left side of the wheel well to the batteries which are under the passenger seat. The antenna cable is at the top.

The RT-246 has pretty much the same wiring set-up w/the farthest connector on the right of the middle three being the power connector (labeled AMT CONT ??).


The RT-442 gets its power through the mounting base. That is why there is no large power cable to the front. The bottom two connectors are (L-R) handset and speaker. There are two antenna connectors on the top depending on which side of the main radio you mount it on to allow flexibility for wire placement.

RT-442 w/left antenna wire


RT-442 w/right antenna wire


This page has a really good wiring diagram for the radios. Unfortunately, my firewall at work blocks the pics and I can't show it here. Hopefully it works for you.

http://federalcavalry.com/


Burik
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Posted: Thursday, January 05, 2017 - 08:13 PM UTC
Wow thanks. So if I put the 246 behind the driver I will have to run the power cable to the passenger seat, correct?
HeavyArty
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Posted: Thursday, January 05, 2017 - 08:46 PM UTC
Correct, two batteries are under the passenger seat and that is where the radio power cables need to go.
Sabot
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Posted: Thursday, January 05, 2017 - 08:48 PM UTC
The R-442 is an auxiliary receiver only and cannot transmit. It has to have the external square box speaker in your verlinden picture so you can hear any incoming transmissions. The RT are receiver/transmitters so you can hear and reply on that radio.

A company commander would have the company net on the main RT and battalion on the AUX. He'd then set the battalion frequency as a pre-set on his RT so he can flip back and forth if he hears battalion calling him on the AUX.

The RT-246 with the pre-set buttons and no speaker are the style usually used in tanks. There is no attached speaker since the sounds will come through the intercom system. The buttons work like old school push button AM/FM car radios and don't always tune the radio to the exact frequency; you often have to tune it by hand a few clicks up or down. The push button just gets you kind of close like a 1970s car radio. Not often seen in Jeeps, but it's possible.
Burik
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Posted: Thursday, January 05, 2017 - 10:04 PM UTC
Thanks Robin for clarifying the R vs RT thing. Nice analogy with the car radio too. Helps me understand a lot better.
thathaway3
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Posted: Thursday, January 05, 2017 - 11:55 PM UTC
The MTO&E (Modified Table of Organization and Equipment, if you can find one, will tell you the exact configuration authorized for the vehicles assigned to each section of a unit, which is based on some staff guy's assessment of what equipment is needed to satisfy mission requirements.

For example, in my FA unit in the 70's which used these radios, the Battalion Commander would usually have two RTs (Receiver/Transmitter) which I believe were both RT-524s as well as one R-442. This allowed him to "operate" (listen and transmit) on two frequencies simultaneously, and "monitor" (listen only) on a third.

A common set up was to set the two RTs to the Battalion Command Frequency, and to the Battalion Fires Frequency, and set the R-442 to the DivArty Command Frequency.

Normally the RT-524 with R-442 were on the passenger's side, and the single RT-524 was on the other side. And you'd have two larger antennas, mounted with "Matching Units" (to facilitate Transmitting on different frequencies) on the stanchions at the rear corners of the vehicle, and the smaller antenna for the R-442, mounted just behind the passenger side door opening, just like in the Gino's photo.

A Battery Commander would usually only have ONE RT-524 and one R-442, mounted on the right side. He'd usually "operate" on the Battery Frequency and "monitor" the Battalion Frequency.

As a Forward Observer, I had one RT-524 on the passenger side, and what was called the GRC-160 on the other side. This was a vehicle mount which allowed you to install the portable PRC-77 and either operate it using the vehicle power and antenna, with the speaker built into the mount, or quickly remove it from the vehicle and jump into the vehicle of the commander of the maneuver unit which I was supporting.

In Gino's photo, you'll notice what appears to be a 1LT sitting in the back and talking on what appears to be a PRC-77. I wouldn't be surprised if this was an Artillery FO.

These radios were not secure, (unless you added a secure device which was totally separate) had somewhat limited range, and because you typically could only operate on a limited number of frequencies, made commo much harder than it is today!!!
dhmundy
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Posted: Friday, January 06, 2017 - 12:11 AM UTC
I was in 9ID (2/4 FA) back in ’83, and the normal “three radio” rig for the Bn Cdr, staff and FIST jeeps was an RT-524 and an R-442 with the two antenna (side and rear) on the passenger side and an RT-524 with a single antenna at the rear behind the driver – all cabling as previously described by others. I don’t recall ever seeing an RT-246 in a jeep, but it might have happened – there was a lot of improvisation. The location of the loudspeaker box varied - it was not permanently attached to anything - so some folks mounted them in back near the R-442 and left the cable coiled up in back, others ran the cable to the front and mounted the box on the dash on the passenger side (that was my preference).
Our FIST jeeps always had an AN/PRC-77 (backpack rig) wedged in somewhere also, like the one in your picture next to the 1LT in the back on the passenger side.
It looks like the jeep in your picture has some additional secure/encryption gear mounted – KY-38 maybe ? – I can’t recall the cabling on those and will have to defer to other more knowledgeable – or with better memories.
BruceJ8365
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Posted: Friday, January 06, 2017 - 01:43 AM UTC
Batteries (2 of them) are located under the passenger seat. The power cables come out of there.

The battery compartment cover is the hump under the passenger seat. The little door you see just underneath the rear of the passenger seat is the tool box. Usually the power cables are routed through a hole cut in the edge of the tool box lid and then it goes into the wall of the battery compartment from inside the tool box.

Radios from the drivers side will have a power cable that goes across the floor and a steel boxed cover over the cable.

I build the 1/1 scale version of these vehicles!

_____

Something I see a lot of modelers get wrong on the MUTT radios is mounting them squarely centered on the rear fender. They actually sit on a little shelf that extends forward.
Burik
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Posted: Friday, January 06, 2017 - 03:49 AM UTC
So I probably should use two RT-524s and an R442? The other devices I will google, but I am not confident they are provided by anybody in 1/35. Maybe the PRC-77 but that other stuff? Anybody know?

Thanks everybody for the input.

Bob

redleg12
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Posted: Friday, January 06, 2017 - 05:28 AM UTC
Bob

It would be rare to have two RT-524 and an R442 in one jeep. As Tom stated a battery or company commander would have one RT 524 and one R442 mounted on the passenger side. The speaker for the R442 would have a wire run and be connected to the dash on the passenger side.

The short antenna for the R-442 would be on the side of the jeep. The full mast for the RT-524 would be on a corner mount at the back of the jeep.

This arrangement would allow a commander to be on his level net and monitor the next level above on the R442.

More than 2 radios would be the S3 or assistant S-3 but they would have more than a jeep

HTH

Rounds Complete!!
Burik
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Posted: Friday, January 06, 2017 - 05:36 AM UTC
Thanks Mike, but I thought I read that another radio could be behind the driver a lot and it would have its own mast on that side. Lots of photos seem
To show two masts one behind the driver one behind the passenger. Im going for the overcrowded look of many photos from Grenada.
HeavyArty
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Posted: Friday, January 06, 2017 - 06:20 AM UTC
Not to contradict my Arty brother, but the three radios as you describe was used by staff officers in Airborne DIVs. In the pic Bob posted, that jeep from 82d ABN in Grenada actually has four radios. It has an RT-524 and R-422 on the passenger side, another unknown radio (most likely another RT-524 or an RT-246) on the driver's side, and a man-portable PRC-77 on the passenger side behind the RT-524.

Burik
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Posted: Monday, January 09, 2017 - 08:09 AM UTC
How long are the antennas? They seem pretty tall. Maybe not the same as today? And what is the white markings on the antennas?





HeavyArty
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Posted: Monday, January 09, 2017 - 05:46 PM UTC
They are he same antennas as the longer ones still in use w/SINCGARS today. They are two-part fiberglass w/a total length of 8 feet (4 feet per section). In 1/35, they are 2 3/4 inches long. The "white" marking is actually a yellow label identifying each section of the antenna w/a part number, serial number, etc. They also have the protective antenna ball on the tip as well.
GulfWarrior
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ARMORAMA
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Posted: Monday, January 09, 2017 - 08:09 PM UTC
I'd LOVE to find one of those old jeeps still serviceable and use it with my ham radio gear!
Burik
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Posted: Tuesday, January 10, 2017 - 08:10 AM UTC
To digress a little; these Grenada jeeps - are they the Merdc with forest green with field drab (and buff and black) winter verdant?
mshackleton
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Posted: Tuesday, January 10, 2017 - 01:23 PM UTC
The antenna on the side is very similar to German aerials like this http://leopardclub.ca/workshop/LW023/ or more possibly http://leopardclub.ca/workshop/LW024/. The whip aerials on the back are http://leopardclub.ca/workshop/LW021B/
HeavyArty
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Posted: Tuesday, January 10, 2017 - 05:44 PM UTC

Quoted Text

To digress a little; these Grenada jeeps - are they the Merdc with forest green with field drab (and buff and black) winter verdant?



Most were a mix of Winter and Summer Verdant MERDC. Some were overall sand as one BDE of the 82d ABN had just returned from a Bright Star Exercise in Egypt and their vehicles had not been repainted yet.

M151 MERDC Summer Verdant Camouflage Color Profile and Paint Guide


Paint Colors:
1: Dark Green - FS 34079
2: Interior Green - FS 34151
3: NATO Sand - FS 30277
Black Squiggles: Black - FS 37038

M151 MERDC Winter Verdant Camouflage Color Profile and Paint Guide


Paint Colors:
1: Dark Green - FS 34079
2: Field Drab - FS 30118
3: NATO Sand - FS 30277
Black Squiggles: Black - FS 37038
Burik
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Posted: Tuesday, January 17, 2017 - 10:24 PM UTC
I'm trying to figure out how to mount these radios. Online photos show a lot of support bars being used which I want to avoid if I can. Others seem to show some sort of direct attachment to the fender, but nothing is that clear. It seems the trays should overhang the front inside portion of the fender, but how are they really attached?







HeavyArty
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Posted: Tuesday, January 17, 2017 - 10:34 PM UTC
The additional support bars were only used when the radios were mounted far forward and overhung the front of the fender. Usually, the mounting base was bolted directly to the fender through the holes Verlinden depicted on the bases. Also, they overhung the insides of the fenders to make room for the folded bows of the soft top to fit behind them. The way you have them mounted in your pics looks perfect.

BruceJ8365
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Posted: Tuesday, January 17, 2017 - 11:58 PM UTC
Usually mounted on a little shelf that allows the radio to be forward on the fender. If you mount it directly to the fender, the radio ends up being kinda behind you when you sit in the back seat.

In fact, the kit for the antenna mast contains the shelf, U channel for running cables across the floor, and even a reflector mounting because to have to relocate one of the side reflectors to put the mount the corner bracket.


I've built several of the real deals. Here's my current daily driver version:

redleg12
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Posted: Wednesday, January 18, 2017 - 06:37 AM UTC
Bruce....love your ride, would love one in my garage..

Bob, I just finished a MERDC paint job, I used the Vallejo latest MERDC colors. Excellent!

Rounds Complete!!
ALBOWIE
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Posted: Wednesday, January 18, 2017 - 09:28 AM UTC

Quoted Text



On the RT-524, the wires across the bottom are, from left to right; handset, speaker, and power (one w/the metal 90 degree connector). The antenna cable is at the top.


http://federalcavalry.com/





The ANT CONT (The one you refer to as power) socket on the front panel of the RT 524 is the control / power cable for the Antenna Matching unit. It's function is to drive the relay and change the filter to match the operating freq of the RT. The Power connector for the 524 comes in as a pin of the multi pin connector on the MT 10129 Mouning tray and cannot be seen although the actual power cable from the vehicle supply can be seen on the bottomn of the Rear RHS of the tray.

Al
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