US Navy Shipboard HF/MF/LF Transmitters
AN/SRT-xx, AN/URT-xx, AN/WRT-xx

Ship & Shore HF Transceivers

VHF and UHF Transmitters and Transceivers

WW2 Transmitters and Transceivers

Equipment Photo Specs Additional Info

Circuit Mayflower

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"The Circuit Mayflower (Shipboard) System is installed on a variety of U.S. Navy ships to provide a one-way-ship-to-shore HF radio link. It consists of an AN/BRT-2 system which has a KY-766A Keyer, TS-3858 silent tuner, modified AN/URT-23, AN/UGC-136CX teleprinter, and AN/USM-488 oscilloscope. The teleprinter is used to control the Keyer and to input various strings of coded messages from a classified codebook. The modification of the existing KY-766/BRT-2 Keyer to the KY-766A/BRT-2 configuration, which began in September 1991, will be completed in FY96. This change modified the existing punched tape reader and associated electronics of the KY-766/BRT-2 and replaced it with a direct electrical interface from the AN/UGC-136CX teleprinter via the SA-2626/BR and black switch board." 

"The Submarine shore HF infrastructure is operated and maintained by the Commander, NCTC and consists of eight HF receiver sites and eight HF transmitter sites. The HF receiver sites support the submarine Circuit Mayflower and Clarinet Merlin systems while the HF transmitter sites rekey the Strategic SSBN submarine broadcast. Functional control of the Clarinet Merlin and Circuit Mayflower programs are in process of being transferred to the Submarine TYCOMs. COMSUBLANT/COMSUBPAC will assume the lead responsibility for operation of the Circuit Mayflower and Clarinet Merlin Systems in their respective AORs. Naval Computer and Telecommunications Area Master Station, Atlantic (NCTAMS Lant) will maintain responsibility for maintenance of the Circuit Mayflower System worldwide. This transfer will start mid FY96 and be completed during FY97."

Possibly related to use of AN/WRA-3 and AN/WRT-4


The submarine emergency communication transmitter (CLARINET MERLIN) buoy, if released, should transmit a coded message at 13 to 15 words per minute. The message should consist of the CW characters “HM,” repeated 10 times, “USS OSC,” and three word groups of three characters each. The transmission is about 3 minutes long on each of four frequencies: 6721.5 kHz, 9033.5 kHz, 11264.5 kHz, and 15055.5 kHz.


bull-agmr1-01.JPG (218889 bytes) 10 KW HF shore station SSB xmtr used aboard communication and command ships and a few others --


WB6ZBX's restored SRT-14
srt14-99.jpg (45398 bytes)
100w LF/HF xmtr
synthesized VFO
4-400 final AM/CW/FSK
manuf by Federal
similar to AN/URT-2

includes -
  TN-229/SRT antenna tuner
  CU-372/SRT antenna coupler
  CU-402/SRT load adjusting unit

srt15-01.jpg (31055 bytes)


Download Manual

article in Electric Radio magazine April 1997 p4


3-01.jpg (106618 bytes) LF/HF xmtr
100w 300kc-2mc
500w 2mc-26mc
synthesized VFO
4-400 final AM/CW/FSK
manuf by Federal
similar to AN/URT-3

SRT-14 plus "booster"
(high-power modulator and 3000v power supply)


Download Manual



srt16-sys-01.JPG (1313681 bytes)  two SRT-14 plus one "booster"

LF/HF dual xmtr
100w 300kc-2mc
500w 2mc-26mc
synthesized VFO
4-400 final AM/CW/FSK
manuf by Federal
similar to AN/URT-4


Download Manual



prototype - what is it? manuf by RCA 1959 NAVSHIPS 92944


prototype - what is it? Manuf by ?
Amplifier design modified by Advanced Technology Corp 1960


urt3-101.jpg (262325 bytes)

Photos - Accessory Units

primarily shipboard use
100w 300kc-26mc
(URT-3, -4 also 500w 2mc-26mc)
4-400 final AM/CW/FSK
10 channel remote select 
(preset frequencies + automatic tuning)

Essentially an auto-tune version of SRT-14, 15, 16 - design predates SRT-14 series

OA-353 Transmitter assembly
C-916/URT remote control

Auto antenna tuner
OA-297/URT controller group +
CB-5/URT capacitor tuning unit +
TN-197/URT inductor tuning unit

Optional "booster" OA-354/URT
(3kv p/s + pair 4-125 modulator)

URT-2 is 100 watts
URT-3 is 500 watts with booster
URT-4 is two URT-2 + booster



design & manuf by Federal - see 
"An automatic tuning communication transmitter" - Dettman, M.
IRE International Convention Record
Volume 1, Issue , Mar 1953 Page(s): 137 - 144
An essentially identical article is here beginning on page 271. An additional article on the automatic tuning system begins on page 279

Additional information

My URT-3 restoration project

Coast Guard only?

urt12-01.JPG (203740 bytes)

more photos

75w HF 2-30 mc AM/CW
pair  4-65's modulated by 4-65's

manuf by Radiomarine 

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photos thanks to Sam KF4TXQ

AN/URT-23 Transmitter

AN/URT-23C aboard USS Iowa
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modern HF SSB transmitter
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T-827/URT - exciter
AM-3924/URT - RF amplifier
PP-3916/UR - power supply
MT-4670/URT-23 - shock mount
used with
   AN/URA-38 - antenna coupler group
       C-3698/URA-38 - controller
       CU-938/URA-38 - coupler

From CNO to CINCPAC 11/68
"The necessity for replacing the AN/SRT series transmitters with high reliability equipment... is a matter of vital interest. The AN/URT-23 will be available beginning in fiscal year 1970 for installation in the active fleet."

My URT-23 restoration project

T-827B/URT exciter
t827-urt-1301-01.JPG (184932 bytes)

t827-urt-1301-04.JPG (151019 bytes)

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T-827/URT model differences page

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ET A School HF Transmitter/Receiver Sub-Systems (1982)
  - covers AN/WRC-1B and AN/URT-23(V)
Vol 3 part 1 - exercises - download pdf
Vol 3 part 2 - diagrams - download pdf

AN/URT-23E transmitter

T-827K/URT exciter
t827k-urt-1309-01.JPG (33355 bytes)

t827k-urt-1309-03.jpg (47492 bytes) AM-3924E/URT amplifier
am3924e-urt-1309-01.jpg (56367 bytes)
am3924e-urt-1309-05.jpg (110534 bytes)

AN/URT-24 Transmitter

need photo

T-827/URT exciter + AM-3007/URT amplifier

100w output 2-30mc

T-827B/URT exciter
t827-urt-1301-01.JPG (184932 bytes)
urc35-120310.JPG (39279 bytes)

AN/WRA-3 HF exciter
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CW exciter for use with AN/URC-32
0.5w or 15w output

Spec sheet

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CY-3022/WRA-3 cabinet
O-1115/URC synthesizer
AM-2819/WRA-3 amplifier
PP-2796/URA-3 power supply

REFERENCE: Final Report on Project 0/S66 FY63 - "Conduct an Evaluation of the AN/WRA-3 Radio Transmitter" 
11 April 1963, SECRET

wra3-14.JPG (1877600 bytes)

wra3-01.jpg (4142801 bytes)

LF Transmitter

wrt1a-31.JPG (125908 bytes) 300-1500 kc AM/CW/FSK
125w AM
500w CW/FSK
Download 64.9 MB pdf


2-30 mc transmitter
500W CW, FSK, AM
1000w SSB/ISB

Click here for more WRT-2 photos

- -

wrt2-1608-01.jpg (1082365 bytes) wrt2-101.jpg (124672 bytes)

AN/WRT-4 Transmitter

1 KW, water-cooled, CW transmitter

wrt4-01.JPG (352106 bytes)

Primarily for submarine use

Spec sheets

-- Need more info

Collins KWS-1 Transmitter

photos thanks to K7DFWKWS-1-NAVY-05.jpg (121142 bytes)

Collins KWS-1 SSB transmitter (modified)

KWS-1-NAVY-01.jpg (155575 bytes)

procured in 1956 along with modified 75A-4 for SSB experiments - KWS-1 was modified to cover Navy frequencies.

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Manual - NAVSHIPS 92787
Standard version
3.0 - 4.0 mc
7.0 - 8.0 mc
14.0 - 15.0 mc
21.0 - 22.0 mc
26.4 - 27.4 mc
28.0 - 29.0 mc
29.0 - 30.0 mc
Navy version
3.0 - 4.0 mc
4.0 - 5.0 mc
5.0 - 6.0 mc
7.0 - 8.0 mc
13.0 - 14.0 mc
14.0 - 15.0 mc
KWS-1-NAVY-04.jpg (145776 bytes) KWS-1-NAVY-03.jpg (142062 bytes) Standard KWS-1 info page