The PRC74 radio was used by the US Army
Special Forces for long range communications in Viet Nam. It was built by
Hughes in about 1965. It is a ‘lightweight’, two-way
communications set that is capable of receiving and transmitting voice (USB)
and telegraph signals (CW). The
original frequency range of the radio set for both receive and transmit modes of
operation is between 2.0 - 17.999 MHz. It has a stability of +/- 1.5ppm from -30 to +55C.
To find an
operating PRC74 these days is pretty rare.
For more details look up "radionerds an/prc-74:.
It
has no subassembly labels, not even adhesive residue from where the labels
would have been. Perhaps to prevent a
captured radio from being identified or repaired.
It
is a PRC74B but has a PRC74C
chassis ID tag. The radio case is desert tan and the battery case is
green. It is mounted on an ALICE Backpack frame. The ALICE frame has a
'Kick Stand' and the Battery Case has 'Swing out' support feet.
It
also has a few Modifications:
The 2 to 3 MHz range has been switched to
1.8 to 2 MHz so it can operate on the 160 Meters USB or CW.
The 17 to 18 MHz range has been switched
to 18 to 19 MHz so it can operate on the 17 Meter Band.
(The original
crystals are included to switch it back to the original bands if desired).
This radio
has over 50 crystals in it. It uses them to mix all the channel
frequencies in 1 kHz steps from 2 to 18 MHz.
It has a crystal rubbering feature so it can operate on any in-between frequency, like 14,342.5 kHz.
It is stable enough to run digital modes. I have used it on PSK-31.
The
battery case has an external charging socket and an External/Internal power
switch.
If the
internal battery gets low you can switch to an external 12V battery.
The
original internal power connector has been replaced
with an Anderson Power Pole type and the battery is a 12 Volt LiIon
(2P3S, 26650 cells) Battery. There is no battery management controller,
(That means you have to turn the radio off or the battery will be
damaged).
It comes with a commercial (Batteryspace) LiIon smart battery charger.
The original final transistors have been
replaced with the improved 2N2876's. There are 2 spare RF Power transistors in the kit,
needless to say these transistors are impossible to find.
The entire rig weighs about 30 pounds with the Li-Ion battery pack.
It comes with
one handset, a H-189 or a H-250 handset, Your choice.
There is also an external audio generator (‘Tuner
Upper’) which allows antenna tuning to
be done in a ‘Safe Mode’ at 5W. It also injects a 400Hz offset tone for CW, which puts the
responding signal audio at 400 Hz, instead of 2,000 Hz. This accessory has a CW
keyer attached. No CW paddle or earphones are included.
This is not one of those "As is" sales, This radio was not just found in a barn, It
works! I have packed it around and communicated with stations all around the world.
You have to
have an FCC license to transmit on this radio.
The purchase includes the original AS-1886A segmented center loaded whip antenna with a "Quick On" adapter.
The 1965
price for this radio was $5560, (The cost of a new Chevy was $2500).
It comes with the very rare AN/PRM-31B Test Set
in new condition. The test set has a Power Meter, Dummy load, a RF Voltmeter, a
DC voltmeter and a signal generator to repair the radio in the field. It also
has instructions how to trouble shoot and repair the PRC74. It has a set of test cables.
A hard copy of the Technical Manual TM 11-5820-590-35-1 is included.
This is a real radio, It has no whiz-bang software or memories that get upset or cause a failure.
Everything is inside is repairable.
You
can read more about the radio by Googling
‘PRC74’.
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