Navy HF Diversity Receiving Systems

Diversity systems use 2 or 3 receivers to copy the same traffic (typically RTTY) from one or more transmitters
Frequency diversity - receivers tuned to different frequencies - to cover shifting ionospheric propagation
Spatial diversity - receivers tuned to the same frequency but connected to different antennas - to cover fading and multipath

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HF Diversity Receiver Systems
model	type	primary use	freq	features	manuf	links
AN/FRR-10		Dual Diversity HF shore SSB (simultaneous USB & LSB) variant of FRR-24 click here for info	2-32 mc	dual diversity 253 tubes	National	info
AN/FRR-24		Triple Diversity HF shore RTTY & CW click here for info	2-32 mc	triple diversity 420 tubes	National	info/photos
AN/FRR-28	two R-450/FRR-28 rcvrs O-165/UR master oscillator AM-615/UR amplifier/detector KY-79/UR keyer SB-224/UR patching panel LS-187/UR speaker	R-450/FRR-28 showing AVC switch and ID tags	0.54-54 mc Dual Diversity HF shore used with AN/URA-8A	uses two Hammarlund SP-600-MX (R-450/FRR-28) R-450/FRR-28 photo FRR-28 at NAVCOMMSTA Kodiak 1959	manuf - Northern Radio info SP-600 manuals	FRR-28 spec sheet - page 1 FRR-28 spec sheet - page 2 Manual - NAVSHIPS 91582
AN/FRR-32			Dual Diversity - HF shore system 2-32mc	two R-618/FRR-32 rcvrs (probably modified FRR-23) O-330/FRR-32 master xtal oscillator CM-70/FRR-32 comparator/keyer SB-431/FRR-32 patching panel LS-169/G speaker CY-597A/G rack	RCA	NAVSHIPS 92736
AN/FRR-37		Dual Diversity version of FRR-24 HF shore RTTY & CW Click here for component info	2-32 mc	dual diversity approx 250 tubes	National	info/photos
AN/FRR-38		Dual Diversity FSK two R-390(*) receivers CV-116/URR dual FSK converter	0.5-32 mc	Signal Corps procurement but used by USN FRR-38 and FRR-41 at NAVRADSTA ( R) Salinas	Collins Hoffman	TM-11-647 TO: 31R2-2FRR38, 31R-1-8
AN/FRR-41		Dual diversity SSB two R-390(*) receivers two CV-157 SSB converters (simultaneous USB & LSB from each)	0.5-32 mc	Signal Corps procurement but used by USN FRR-38 and FRR-41 at NAVRADSTA (R) Salinas	Collins others	TM 11-649 TO: 31R2-2FRR-221
AN/FRR-42 AN/FRR-43	Similar to AN/FRR-24	Click Here for Info
AN/FRR-51	need photo	Dual-diversity HF with 10 channel auto-tune R-792/URR receiver (2 ea.) CU-560/URR antenna coupler C-2087/URR receiver control C-2086/URR remote switching control CV-116/URR FSK converter CV-395/U Signal Data Converter CY-1119/U cabinet	need info	need info - please send e-mail
AN/FRR-60	photo from TMC vintage radio web site	HF shore diversity system NAVCOMMSTA Guam - 1960's	info needed	Info - AN/FRR-60 Page	TMC DDR-5
AN/URR-49	Guam 1968 - URR-49 configurations	HF shipboard/shore FSK dual-diversity system two R-390A receivers AN/URA-8A dual FSK converter	info needed	Nomenclature was assigned and configuration was widely used, but I'm not sure it was ever procured as URR-49
REA part of AN/FRC-10	photo	Western Electric triple diversity for pt.-to-pt. VF AFSK links 4-23 mc dual channel SSB (crystal controlled?)