Wednesday, May 13, 2009
T.M.C. GPR-90 Comunication Receiver. (SOLD)
It Was made in Ottawa Ontario CanadaTechnical Materiel Corporation, or TMC, was founded in 1934 by Ray DePasquale and, by the early 1950s, had become a major supplier of receivers, transmitters and accessories for the military and for commercial users. TMC introduced the GPR-90 communications receiver in 1955 with a selling price of $395. The circuit used 15 tubes and provided several unusual features, such as a three-position audio filter with adjustable audio bandwidth (on 1200~ position,) the multi-impedance output taps on the audio output transformer (4, 8, 16 and 500 ohms Z) and a great performing, wide range crystal filter. The circuit also featured two RF amplifiers on bands 3, 4, 5 and 6 (3.3mc - 31.5mc) along with double conversion on bands 4, 5 and 6 (5.4mc -31.5mc.) The first RF amplifier is a grounded-grid configuration with a wide-band input transformer to allow both 75 ohm Z and 300 ohm Z input impedance's over the entire tuning range of the receiver. The cabinet was painted an unusual dark blue wrinkle finish and had an easily removable top lid for access to the top of the chassis. After the first year of manufacture, a 100kc crystal calibrator was installed and the selling price increased to $495. The military used the GPR-90 and identified it as the R-825/URR.