VIC-4 intercom manual and VIC-1/VIC-4 mods

[OPCOM]

Been working with the VIC-4 intercom system. This is like the VIC-1, except it controls 4 tranceivers where the VIC-1 controls two tranceivers and one receiver.

When working with one of these to interface a CB radio or other non-FM tranceiver, there can be issues of the transmitted RF signal getting back into the mike wiring of the headset causing a squeal. The noise primarily gets into the system through the headset's 6-FT coily-cord and also through the long cable from the crew box to the amplifier (mine is 21 FT long).

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tech note -skip if not interested about why the problem happens:
For sure some RF from the VRC-12 FM radios gets into the VIC intercom. The reason that FM does not bother it is that an FM signal keeps the same 'power' level at all times and only varies the frequency slightly -for instance, when you set the RT-524 to 51 MHZ and you speak, the actual frequency of the radio varies from 51.010 to 50.990 MHz according to the speech but remains at the same 35 watt power level, while an AM or SSB signal from the CB radio remains on the same frequency but varies the RF power from 0 to 12 watts with the voice syllables. The electronics in the VIC cannot process RF, but are affected by sudden changes in the RF power picked up, especially if these variations are in the speech range that the VIC is designed to reproduce.
It gets far worse with a powerful ham radio (and I have never heard of a 400 watt GRC-106 being used with the VIC-1 or VIC-4.) One solution is to reduce the TX power on the CB, but it only has 4 watts to begin with. Another, and probably better solution is to get more technical and install bypass capacitors in the crew boxes to help kill off the RF.

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I have the -30 manual for the ViC-1, and while is it of some help, I need the manual for the VIC-4. I need this because I need the pinouts of the crew box-to-amplifier plugs. Although the systems use the same cables and headsets, the pinouts are not the same as the VIC-1 and the amplifier unit is extremely different inside.

Here's the deal: I would be willing to pay for a VIC-4 manual, particlularly the direct support maintenance manual with the large fold-outs and schematic wiring diagrams. Nobody seems to have one, and it's not shown in the index of the usual web sites. I can only hope that one has come out along with the VIC-4 units through DRMO.

I have been trying to work this issue but the VIC-4 is rather highly integrated and things are not so easy to deduce. My attempts have reduced but not eliminated this annoying problem.

Please PM me if you have a manual for the VIC-4. If necessary, I am willing to make a copy and reutrn it.

If by chance I am successful in RF-proofing the VIC-4 with or without the books, I'll post the details in an article. I will also address the same issue for the VIC-1

Thanks,
SSG PJ

 

[Attackpilot]

SSG PJ,

I have a NOS VIC 4 control box. It was part of a package deal collecting comm stuff. Is anyone interested in this sort of set-up. Since the guys have been helpful in my com quest......here n steel solider, I thought I would offer here first if appropriate.

As I understand it can control 4 radios vs 2. I believe it uses different control station boxes. My understanding is that it is compatible with the VIC 1 system. Any pics in jpg format of all the equipment like above.

 

[CARNAC]

If it is the same one pictured, these were used in the FIST-V artillery spotter vehicles. You are correct in controlling multiple radios. About the only compatible items are the cables, radio mounts and the power protection box.