R-129/U version of Hammarlund SP-200 Hammarlund SP-200, R-129/U version
The Super-Pro series 200 is probably Hammarlund's finest prewar receiver. A full page ad introducing the SP-200 can be found in the October 1939 issue of QST magazine, page 73. (Was the choice of page 73 random? :-) An article on the new receiver appears in the November 1939 Radio News. The SP-200 sports 16 tubes on its chassis plus 2 in the separate power supply. Full page ads appeared in QST about once a month for an entire year. According to the November 1940 QST ad, "The fact that 'Super-Pro' receivers are used extensively by the U.S. Signal Corps and many other governmental departments, speaks for itself. Use the set the experts use." Newark Electric advertised the set for $279 in its Christmas 1940 ad, twice the price of the HQ-120X.
This one served in the military during WW II. Order number 3027-PH-42, serial number 53. The R-129/U variant covers from 300KHz to 10MHz in 5 bands. The power supply on the SP-200 is separate. The rack panel cabinet shown is generic but fits nicely.
All of the SP-200 sets are single conversion. The bandwidth is continuously variable from 3 to 16 KHz by a control which mechanically varies the coupling on IF transformers. A crystal filter allows even narrower bandwidths, down to "better than 1 Kc". Specified sensitivity is one microvolt. Audio power output is rated at 14 watts from push-pull 6F6 tubes with a third 6F6 used as the transformer-coupled driver. The sound from these sets is excellent with the proper speaker. Even a phono input is provided. The most common military version of the SP-200 is the BC-779A and BC-779B. The BC-764, BC-794, BC-1004 and R-270/FRR are also military variants of the series.
For lots more SP-200 info check out Josh Rovero's page.