PRD-1

© Brooke Clarke, N6GCE

PRD-1

Background

The PRD-1 is an H.F. receiver designed for direction finding. It can be mounted on it's special tripod or using a special mount that allows leveling of the radio, on the fender of a jeep , like the M38A1. It was used in Vietnam and possibly the Korean conflict. SP4 James T. Davis was an american advisor in Vietnam helping the ARVN to use the PRD-1 and was the first American killed in Vietnam.

This is a tube type radio.

The PRD-1 did not work well against transmitters using Near Vertical Incidence Sky wave antennas. These "cloud Burner" antennas send the H.F. signal straight up and when it bounces back covers hundreds of miles from the transmitter location. Much better coverage than you could get with a 1/4 vertical whip antenna, but nowhere close to the range of a good horizontal dipole antenna or beam. The NVIS antenna is good for comms in a battle situation and provides better coverage than VHF radios. Since the sky wave is coming down at a steep angle the loop antenna on the PRD-1 does not give good results.

Overall Photo with Dynamotor power supply under R-395.

PRD-1

I have removed the spare fuse to allow wires for plus and minus 28 VDC to get out of the case (the fuse holder is in a transit case.
The 28 Vdc Power cord has a BIG connector with 3 male pins that goes to the M38A1 or other power source.
The loop has a sense antenna that is over six feet long in the center of the square loop to provide unambiguous direction indications.

I got this set from Fair Radio many years ago and at that time it was operational in my living room.
On a number of frequencies you could hear two or maybe 3 stations on the same AM broadcast frequency by rotating the antenna.
I have not turned it on and am selling is AS IS condition.

ASA Lives - former PRD-1 users and related info on the set.

CY-949/PRD-1

R-395/PRD-1 Receiver

Covers 100 Kc to 30 Mc. The CY-949 transit case is in the background to the right of the of the photo.
When I was using this radio many years ago I could hear many broadcast stations. In many cases 2 or sometimes 3 stations could be seperated on the same frequency by rotating the antenna.

Right Side Photo -

Front Panel while mounted on Dynamotor P.S.

CY-947/PRD-1 Battery Box

Holds a lot of batteries and the bottom mates to the tripod and the top mates to the bottom of the 395 receiver.
1 each type BA-404/U is connected to pins D & A supplying +1.5 V for filiments
4 each type BA-404/U are connected is series to pins B & A (and also to E & A) supplying -6 V.
2 each type BA-419/U are connected in parallel to pins C & A supplying +90 V (B+).

CY-950/PRD-1

MT-870 Tripod
Loop antenna
sense antenna
AN/PRD-1 Compass Adapter
32374 Open end & hex wrench
SM-B 133852 Tool
Spare Fuse from DY-79 front panel
"T" handle casting with small Allen wrench

CY-954/PRD-1

DY-79/PRD-1 Dynamotor
I have removed the spare fuse in order to bring out the 20 to 32 VDC power wires. The bottom mates to the tripod and the top mates to the bottom of the 395 receiver.
CX-2269U Cable
One connects to the DY-79 and the other end has 3 male pins that go the the M38A1? or outer power source.

MT-1283/PRD-1 Jeep Mount (M38A1?)

This mount has provision to level the receiver even when the jeep is on sloping gorund.

Figure 25 from the manual showing the PRD-1 mounted on the jeep.

Manual Partial Copy

TM 11-667 Direction Finder Set AN/PRD-1
This includes theory of operation, many schematics, alignment procedures, etc.

Photo of the Set

PRD-1

CY-947 Battery Box 12#, 16x14x5"
CY-950 Transit Case with loop antenna & tripod 71#, 42x16x10"
CY-954 Transit Case with DY-79/PRD-1 Dynamotor 105#, 22x20x22"
CY-949 Transit Case with R-395/PRD-1 Receiver (175#), 28x21x27h
MT-1283/PRD-1 Jeep Mount (70#)

Related Equipment FOR REFERENCE ONLY

AN/PRD-10 Manpack Radio DF Set [MPRDFS]

AN/PRD-11 Radio Receiver Direction Finder Set (NSN 5825-01-188-3435)
Called "MINI-FIX", see the FAS web page on AN/PRD-11, MINI-FIX

AS-3732 (20 - 175 MHz) or AS-3733 (20 - 850 MHz) Antenna

IP-1355 Panoramic Indicator - spectrum display

AN/GRR-8(V) Receiver, Tuners: TN-586 (0.5 - 30 MHz), TN-584 (20 - 250 MHz), TN-585 (250 - 500 MHz)

C-11495 Processor Display Control - digital and compass rose displays of bearing

Speaker Assembly

CV4090, up-converter

Manuals

TM 11-5825-278-12-1 (063258.pdf) = restricted

TM-11-5825-278-12-2 (ETM 058582.pdf)

TM 11-5825-278-12-3 (064718.pdf) = restricted

TM 11-5825-278-23P (061798.pdf) = restricted

AN/PRD-12, Lightweight Mantransportable Radio Direction Finder System (LMRDFS)

Manpacked 60 lbs Carried by 2 soldiers

Comm intercept/DF system; on emitter location missions, works with TEAMMATE; ideal in LT, Abn, ASSLT, SOF Ops,. Rapid relocation; optimizes collection in forward Area of Operations

FM 34-1 Intelligence and Electronic Warfare Operations- Chapter 2 - Fundamentals of IEW Operations -
How To Net an AN/TRQ-32a(V)2 With an AN/PRD-12 -

AN/TRQ-23

This is also a DF set.
AN/TRQ-32V Receiving set TEAMMATE

HMMWV

EA (jam): COMINT

AN/MLQ-38 Ground-Based Common Sensor Heavy & AN/MLQ-39 Ground-Based Common Sensor Light

Hvy: Electronic Fighting Vehicle (XM5), Lt: HMMWV

Intercept and DF: COMINT and/or ELINT EA(jam): COMINT Targeting location data Data downlink to CGS

USMC Mobile Electronic Warfare Support System (MEWSS)

Directional Finder (DF) System (AN/PRD-10)

Two Acquisition Receivers (WJ-8618B)

Intelligence and Electronic Warfare Common Sensor (IEWCS)
Section XI. EQUIPMENT -
AN/FSQ-144V (TROJAN)

is the Army's remote collection system supporting in-garrison collection by tactical MI units.
FM 24-33 Communications Techniques: Electronic Counter-Countermeasures. 17 July 1990.
FM 34-40 (S)Electronic Warfare Operations (U). 9 October 1987.
FM 34-40-7 Communications Jamming Handbook. 23 November 1992.
M 100-5 Operations. 19 June 1993.

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