Production Year 1951 - 1972 at $985.00 - $1140.00
The Hammarlund SP-600 is a Dual Conversion Super heterodyne receiver using 20 tubes and covering from 540kHz to 54MHz. The receiving modes are AM and CW.
The tubes and their functions are as follows, two 6BA6 = RF Amp, 6AC7 = FFO, 6C4 = VFO, two 6BE6 = Mixer, 6BA6 = Gate, 6C4 = FFO, two 6BA6 = IF Amp, 6BA6 = Driver, 6BA6 = Buffer, 6C4 = BFO, 6AL5 = Detector & AVC, 6AL5 = Limiter & S-Meter, 12AU7 = IF Out & AF Amp, 6V6GT = Output, 0A2 = Regulator, 5R4GY = Rectifier and a 6AL5 as a Rectifier
The SP-600 is single conversion under 7.4 MHz. There are Four IF and two RF stages. The features include a 1/4" Headphone Jack, Signal/AF Meter, IF Output Jack, AVC On/Off, Standby switch, Tuning Lock, 6 Fixed band Positions, Crystal Fine Tuning of ±3 kHz, BFO of ±3 kHz, Internal Power Supply, Flywheel Tuning, RF Gain and a ANL.
The matching Hammarlund speaker would be the SP-300.
Some Variants include the SP-600-J which has no fixed positions.
The SP-600-JLX-2,15,23 covers the .1 to .4 and 1.35 to 29.7 MHz.
The SP-600-JX-17(as pictured) is a diversity receiver.
The SP-600-VLF-31, 38 is only 10 through 540kHz.
The SP-600-JX-21A has 22 tubes and SSB.
The SP-600-JLX-27 covers .2 to.4, and .54 to 29.7 MHz.
Some of the common military designations for this receiver is as follows.
The SP-600-JX-28 is also known as the R-620.
The SP-600-JX-6 is also known as the R-274B.
The SP-600-JX-12 is known as the R-274A.
The SP-600-JX-29 was for the CIA.
The SP-600-JX-39 was used at the FAA.
The size of the radio is 21.5 x 12.75 x 17.25" and it weighs in at 87 Lbs!!