|PRODUCTION DATE||SUFFIX #||NOTES|
|Sept. 1951||SP-600-JX-1||Std. Frequency range 540 khz-54 MHz. Also designated R-274A/FRR ("Fixed Radio Receiver") Signal Corps order no. 1689-Phila- 51-01. Note: many early SP-600's were simply designated SP-600-JX|
|Sept. 1951||SP-600-JLX-2||Frequency range 100-400 khz, 1.35-29.7 MHz|
|Sept. 1951||SP-600-J-3||Std. Frequency range, 540 khz-54 MHz. No X-tal frequency control.|
|Sept. 1951||SP-600-J-4||Std. frequency range, 54O khz-54mhz. No X-tal frequency control. Equipped with 25 to 60 cycle ( hertz ) power supply. Signal Corps. R-320A/FRC, order no. 21478-Phila-50-06. Also has separate IF gain control located where the X-tal frequency control was normally located. Part of OA-58B/FRC Set.|
|Sept. 1951||SP-600-JX-6||Std. Frequency range, 540 khz-54 MHz. BFO range 0-10khz. U.S. Navy model R-274B/FRR, order no. Nobsr-52039 19 October, 1954. Navships manual 91661.|
|Sept. 1951||SP-600-JX-7||Std. frequency range, 54O khz-54mhz.|
|Sept.1951||SP-600-JX-8||Std. frequency range, 54O khz-54 mhz. Manufactured for Welch contract no. XG-479. Believed to be a cover for a CIA contract.|
|Sept. 1951||SP-600-JL-9||Frequency range, 100-400khz, 1.35-29.7 mhz. No X-tal frequency control.|
|Nov. 1951||SP-600-JX-10||Std. frequency range, 54O khz-54 mhz. Replaces JX-7.|
|Nov. 1951||SP-600-J-11||Std. frequency range, 54O khz-54mhz. No X-tal frequency control.Note: This model made to complete NAVY order, without the changes per ECN1156 as standard J series. Replaces J-3.|
|Nov. 9, 1951||SP-600-JX-12||Std. frequency range, 540 khz-54mhz. Signal Corps. R274A/FRR, order no. 3376-Phila-52. Replaces JX-1.|
|Nov. 26, 1951||SP-600-J-13||Std. frequency range, 54O khz-54mhz. No X-tal frequency control. Signal Corps. order no. 16838-Phila-51. Serial no's. 52 to 67 inclusive. 25 to 60 cycle power supply. Replaces J-5. 16 receivers produced on this order.|
|April 23, 1952||SP-600-JX-14||Std. frequency range, 54O khz-54mhz. Signal Corps. R274C/FRR, order no. 3376-Phila-52. Also designated previously as R-542/FRR. Replaces JX-10.|
|June 17, 1952||SP-600-JLX-15||Frequency range, 100-400 khz, 1.35-29.7 mhz. Replaces JLX-2.|
|June 17, 1952||SP-600-JL-16||Frequency range, 100-400 khz, 1.35-29.7 mhz. No X-tal frequency control. Replaces JL-9.|
|June 17, 1952||SP-600-JX-17||Std. frequency range, 54O khz-54mhz. Diversity receiver. Manufactured for Air Material Command. Note: easily identified by 'red metal knobs'. The most common of the SP-600 series receivers.|
|June 26, 1952||SP-600 JX-18||Std. frequency range, 54O khz-54mhz. Made for ' GAUVREAU ' contract. Replaces JX-10.|
|Aug. 27, 1952||SP-600-J-19||Std. frequency range, 54Okhz-54 MHz. No X-tal frequency control. Equipped with 25 to 60 cycle power supply. Replaces J-5, J-13.|
|Aug. 1952||SP-600-J-20||Std. frequency range, 54O khz-54mhz. No X-tal frequency control. Same as J-19. Signal Corps. R-483A/FRR, order no. 3479-Phila-52-05. Equipped with 25 to 60 cycle power supply. Replaces J-19.|
|Feb. 13, 1953||SP-600-JX-21||Std. frequency range, 54O khz-54mhz. Replaces JX-10.|
|Feb.1953||SP-600-J-22||Std. frequency range, 540 khz-54mhz. No X-tal frequency control. Replaces J-11.|
|Feb. 1953||SP-600-JLX-23||Frequency range, 100-400 khz, 1.35-29.7 mhz. Replaces JLX-15.|
|Feb. 1953||SP-60O-JL-24||Frequency range, 100-400 khz, 1.35-29.7 mhz. No X-tal frequency control. Replaces JL-16.|
|Feb. 1953||SP-600-J-25||Std. frequency range, 54O khz-54mhz. No X-tal frequency control. Equipped with 25 to 60 cycle power supply. Replaces J-19.|
|Feb. 1953||SP-600-JX-26||Std. frequency range, 54Okhz-54mhz Signal Corps. R274C/FRR, order no. 3376-Phila-52. Effective upon Signal Corps. approval of TAR#10 dated 2-12-53. Replaces JX-14.|
|March 13, 1953||SP-600-JLX-27||Special frequency range, 200-400 khz, 540 khz-29.7 mhz.|
|Oct. 5, 1953||SP-600-JX-28||Std. frequency range, 54O khz-54mhz. Signal Corps. R-620/FRR, order no. 25693-Phila-53-61, contract DA-36-039-SC-49453, 100 units built, s/n 15001-15100. Several ckt modifications.|
|March 12; 1954||SP-600-JX-29||Std. frequency range, 54O khz-54mhz. Made for CIA contract no.XG-1178.|
|Dec. 28, 1954||SP-600-JX-30||Std. frequency range, 54O khz-54mhz. Diversity receiver. Replaces JX-17 red metal knobs, not very common.|
|Dec. 1954||SP-600-VLF-31||Special frequency range, 10-540khz X-tal frequency control (4 position). Very low frequency receiver.|
|Dec. 1954||SP-600-JX-32||Std. frequency range, 540 khz-54mhz. Black wrinkle finish front panel with white engraved lettering. Made for Mackay Radio, their order no. M-41666, Hammarlund production order no. 2467- 300. Internally the same as JX-21.|
|Dec. 1954||SP-600-JLX-33||Special frequency range, 100-400 khz, 1.35 - 29.7 mhz.|
|Aug. 7, 1956||SP-600-JL-34||Special frequency range, 100-200khz, 54O khz-14.8 mhz. Made for CIA. Their order no. XG-1765.|
|Aug,. 1956||SP-600-JX-35||Std. frequency range, 540 khz-54mhz. X-tal frequency control. BFO range 0-10 khz. U. S. Navy R-274B/FRR, order no. NObsr-71369. Navships manual 91661.|
|Oct. 3, 1957||SP-600-JX-36||Std. frequency range, 540 khz-54mhz. X-tal frequency control. Made for FBI, their order no. FBI-16876, their contract no. J-FBI-3873. Same as JX-21, except for addition of audio input jack on rear of chassis.|
|Oct. 9, 1957||SP-600-JL-24
( Special )
|Frequency range, 100-400 khz, 1.35-29.7 mhz. No X-tal frequency control. U.S. Navy R-274B/FRR. Supplied to NAVSHIPS 91661, R-274B/FRR per PL-33910-1. Reason for 'Special' designation not known.|
|Mar. 28, 1961||SP-600-JX-37||Std. frequency range, 540 khz-54mhz. X-tal frequency control. 25 to 60 cycle power supply. Otherwise, same as JX-21.|
|March, 1961||SP-600-VLF-38||Special frequency range, 10-540 khz. X-tal frequency control (4 position). Very low frequency receiver. 25 to 60 cycle (hertz) power supply. Same as VLF-31 except for 25 to 60 cycle (hertz) power supply.|
|July 21, 1961||SP-600-JX-39||Std. frequency range, 540 khz-54 mHz. Made for FAA contract no. FA-2338.|
|June 1969-1972||SP-600-JX-21A||Std. frequency range, 540 khz-54 mhz. This was the last series of SP-600's manufactured. It had 22 tubes vs. 20 in other models. Also, a separate product detector, LSB,USB,CW,MOD switch. Appearance was different from other SP-600's in that the knobs had no metal skirts, the front panel was engraved with markings for Xtal phasing, selectivity, bfo, audio gain, rf gain. Also is marked JX-21-A on front panel. This is probably the rarest of the SP-600 series. Click Here for SP-600-JX21A Pictures|
|The information above, came from engineering revision ' sign off ' sheets,
Robert Fowle obtained from the late Wayne Cordell,
last Administrative Sales Mgr for Hammarlund, and
are only approximate dates. |
Les Locklear condensed and retyped it all for this format.
Note from Les Locklear:
Over the years, many articles have been written on the performance and modifications of the Hammarlund SP-600 Super-Pro receivers.
Most state (incorrectly, I might add) that production ended with the JX-26.
After a great deal of research, telephone calls and conversations with SP-600 owners and having owned 19 of these fine receivers, this list was compiled.
Most of this information was taken from a "Hammarlund model number designation for type SP-600xx receivers list". The dates are engineering revision dates taken from the engineering revision "sign off" sheets, so are only approximate production dates.
The only SP-600's not included on this list that I'm aware of are the "hybrid" SP-600's manufactured during the Vietnam war. The military designation was R-1511/GR. These models used only 9 tubes, dual voltage regulators, 8 printed circuit boards and a 200 khz bandpass filter. usually used in banks of 5 receivers and connected to video recorders. They were used for signal intercept work in the hf spectrum to detect where the enemy was talking. The reels of tape were sent to the NSA in Ft. Meade, Maryland for interpetation. (We have a manual for this unit on the "manuals" page.)
Although many SP-600's were used by the Naval security group for signal intercept work, I don't believe that SP-600's were ever used aboard naval ships, only at shore installations.
Another variant was the R-450/FRR-28. These were standard Hammarlund JX receivers that were modified by Northern Radio; USN stock no. F 16-Q-112117-200, contract number Nobsr-52132, 19 December, 1950. These were designated SP-600-MX. Installed in a relay rack cabinet with a LS-187/UR speaker, AM-615/UR amplifier detector, KY-79 keyer, O-165/UR high stability oscillator, S-224/UR patch panel and an AN/URA-8 fsk converter-comparator. The X-tal frequency control at the top r.h corner was removed and covered with a Buships/Northern Radio order no. nameplate. Northern Radio located in New York City made many modifications available for SP-600's such as an IF gain control located where the dial lock was normally located. This was a very common military modification.
Hopefully, this will help SP-600 owners and users in identifying various models of Hammarlund SP-600 receivers.