PRC-47
The PRC-47 is a complete portable high-frequency communications system
including antenna and accessories, designed by Collins in the late fifty's or
early sixty's. The radio set provides CW and USB transmission and reception
in 1kc increments over the frequency range of 2 to 12mc. The equipment is
also capable of FSK communication when used with a FSK converter. The radio
set may be used in portable, vehicle, and fixed station applications. In the
portable application, two men can pack the complete equipment. For this
application, the radio set is powered by a 24-volt battery that is part of the
equipment. For mobile applications, the radio is mounted in a vehicle and
powered by the vehicle's 24-volt charging system. For fixed station use the
radio may be powered by a 115-volt 400-cps power supply. Power out of the
transmitter is about 20 watts in low power or about 100 watts in high power.
The radio is designed to match a 15-foot whip mounted on the radio or it will
match a long wire or a resonant antenna. It is a hybrid unit using 4 tubes
and the rest of the radio uses solid state devices. It uses plug in modules
so the trouble shooting can be real easy if you have the extra modules or a
pain if
you don't.
I have two of these radios, one is complete with all of the accessories other
than the 24-volt battery, and the second one is a parts radio. I changed out
the LSB filer and replaced it with a USB filer, this change puts the radio on
LSB, and the CW still works the same. I use two 12-volt garden tractor
batteries in series for 24-volt operation. It is real easy on the batteries
only drawing 600MA on receive. I have used this radio in a mobile setup by
using the two batteries in series and charging them at night. Also this radio
works well for portable work eather with the 15 foot whip or dipoles. It's
weatherproof, matches almost any kind of antenna, and you don't have to take
your new 1000.00 radio out in the weather. The transmitter uses speech
processing and VOX operation. I have set it up in the military portable
application, using the 15-foot whip and ground plane setup that comes with the
radio and worked Ca on Low power using CW.
The down side to this radio is the 1kc steps, the 24-volt operation, and it
size. The first photo is a line photo out of the manual, the second photo is
my working PRC-47 that I have setup on the radio bench.
Since I wrote this page, I have acquired an CV-2455/ FSK Converter for the
PRC-47. This accessory allows the PRC-47 to transmit and receive RTTY
signals. It also has a built in loop supply for the teletypewriter and a
blower for the transmitter to allow for the 100% duty cycle of FSK. The
converter
is setup to use 850 cycle shift and provide 20MA or 60MA loop current for the
teletype. It also is setup for remote PPT control. The
instruction sheets that I got with the TU, talks about using a AN/TGC-14A(V)
teletypewriter with it. I have it hooked up to a Model 15 teletype at the
monent and I am getting ready to bring a model 28 KSR teletype online as
well.
On the air using the PRC-47 in the FSK mode has been a real kick for me! I
havn't used a teletype on the air in over 20 years! So having the model 15
running and the DC supply and the converter blower running on transmit makes
for a noisy shack, but a cheerful one! There was four stations on the
frequency (10.137) that morning, three of us were using the PRC-47 /CV-2455
setups! I was running high power (about 100 watts into a dipole) with no
problems or overheating of the transmitter or power supply. I havn't tried to
use it yet when the bands are noisy or busy, so I am not sure how it will copy
under that type of operation.
Since I wrote that article about using the CV-2455 with the PRC-47 an years
worth of Saturday morning QSO's have gone by. The setup works very well on 30
meter band providing good print day in and day out.
On using the radio in a portable configuration, we have all ways had problems
with RF feedback into the Mic when using the 15 foot whip on on the radio. To
get around this problem all you need to do is add an counterpoise to the ground
system. When I was at Ft Steven's last summer I had time to check out this
idea. I used two 40 foot lenghts wire spead out in a straight line with the
radio in the center, this took care of the feedback problem and I was able to
talk with Al W6GER on 7296 USB with no problem when using the 15 foot whip!
updated 03-31-2002
