The radio set provides voice, narrow-band data and narrow-band or wide-band CW. Both SSB and AME are provided for voice and data operation. The SSB mode is used for CW and in the SSB mode both USB and LSB are provided.
An automatic antenna matching unit is built into the radio set, for matching almost any antenna over the frequency range of the radio.
The radio set is all solid state with a average transmitter output of 20 watts and low current draw on receive.
Here is more info that I got from the NET.
- Back-pack, Vehicular HF, SSB/AM/CW & data transceiver. A U.S. designed system, the PRC-174 is built in Israel by Tadiran & is part of their HF-700 series of equipment. The Basic RT-936 serves as the heart of several portable or vehicular configurations, with optional power levels of 20 to 500 watts. - Features include digital synthesis with six push-button frequency selection, LSB/USB/DSB(AME)/CW(narrow)/CW(wide) modes, & automatic silent tuning. - Ops 2-30mc in 100cps steps for a possible 280, 000 channels.RF power output is rated at 20 watts. Requires 22-32vdc supplied by batteries (silver zinc or nicad rechargeable).Size 2 11/16"H x 10 5/16"W x 11 5/8"D, 12.5 lbs(less battery). - Known accessories/configurations include, compatibility with earlier generation antennas, audio accessories, power supplies, & mountings, also specially designed automatic test sets, & remote control equipment. AM-1760 100 watt amplifier & OA-807 mount(VRC-176). AM-4760 500 watt amplifier & OA-807 mount(VRC-476). Introduced in 1978. Well that gives you an overview of the radio from the Military viewpoint.
Nothing wrong with the packing or any thing like that, but I think there must be some high frequency vibes from the plane that loosens that hardware. The only copy of the operator's manual that I have found is pretty poor, but all that I have been able to come up with so far.
The radio uses a side mounted whip in the manpack configuration. It uses a unique way of switching the internal antenna tuner from either the front panel BNC antenna connector or the whip antenna mount on the side of the radio by means of a small magnet in the whip antenna base. I found out that the radio will receive on either of the antenna ports, but if you want to use the BNC panel mounted connector you need to remove the side antenna mount.
As far as batteries go the radio runs on anything from 22 Vdc to 32Vdc. It draws about 140 Ma on receive and up to 4 to 5 amps on transmit. This makes it very easy to use the newer battery technology that is in use today. I built a battery for it out of 2700 Ma AA nickel-metal hydride cells. I used 20 cells in series and then 3 sets of 20 in parallel for about 27.5 Vdc fully charged at 7.5 Amps. Here are couple of photos of the battery that I built. When soldering to the cells you want to use a large soldering gun with a lot of heat, pretin the cells and solder on your wires or braid connections quickly so that you do not damage the seals on the cells. I used the black tape for ease of assembly and repair / replacement of cells.
The radio will work with voltages as low as 22 Vdc, but at 20 Vdc will start sounding an alarm and flashing the red led meter to protect its self, as well as the battery. I bought 60 of the cells for $50.00 (2007 prices Christmas special) plus shipping and then 39.95 plus shipping for a charger to charge them properly. This will pretty much run the radio for the whole weekend.
Here are some web sites where I found good prices on batteries and chargers.
The radio works quite well on both SSB and listening to short wave stations on AM. The Internal antenna tuner does a good job with both whip antennas and dipole type antennas. I also have used it with the Collins NVIS type crossed dipoles very good results on a weekend campout. The tuner checks for a correct match every time that you transmit this makes it real easy to use an external RF keyed amp. It uses the standard PRC-25-77 audio acc's using the U-229 connectors and has enough audio to drive a LS-454 speaker. I found a backpack Harness for the radio. This one looks like the ST-138 pack frame for the PRC-25/77 radios. The built in metal shelve is mounted much lower on the harness and it is marked PRC-174.
The photos show my first PRC-174 with a large battery box and a home brew whip mount. This was a RT-936. I have since got a RT-936 with the normal sized battery box and different whip mount. I will be adding more photos of the new radio and the battery that I built up from AA cells.