while the output of the LINE AUDIO provides a 10 mW output Into a 600 ohm balanced line. 75 watts with a 3.0 uv signal, 30% modulated. Collins 51s-1 receiver round emblem dial lock good condition. 1 second (fast) release time = 1 second (slow).ħ0E-24 permeability tuned oscillator (PTO). Dial accuracy is 300 cycles after calibration.ġ.0 microvolt for 6 db signal-to-noise ratio with 3 kc bandwidth.Īudio Output rise is less than 3 db for inputs of 5 to 200,000 uv.ĪVC Time Constants: rise time =. Temperature stability is less than 1200 cycles drift from 0 to +/- 60 degrees C. Warm-up drift is less than 300 cycles after 15 minutes of operation. IF rejection at center of each band is 70 dB or better. Image ratio at center of each band is 50 dB or better. Other options include an external cabinet mounted speaker (270G-2). A built-in 100 kc crystal calibrator is included as standard. Separate detectors are used for AM and CW-SSB.Īn adjustable noise limiter is incorporated for AM and CW operation. The passband tuning feature is accomplished by gang tuning the BFO and variable frequency oscillator using a metal belt.Ī "Q" multiplier stage is used to provide a tunable notch to minimize heterodyne interference. Accurate tuning is accomplished through the use of a slide rule megacycle drum dial and a vernier kilocycle dialĬalibrated in 1 kc increments. This provides optimum selectivityįor single sideband reception.
Offers a rectangular selectivity curve with steep skirts for rejection of adjacent frequency interference. Mechanical filters using 9-pin miniature tube sockets, the 3 kc factory standard and optional filters for AM and CW. The SEM-25 covers 26.00 to 69.95 MHz, in 50 kHz steps. This fine collection of Collins KWM2 & 2A, 75S Rxs, 32S Txs, 51S1 Rx and 30L1 linears.
COLLINS 51S 1 600 OHM LINE OUTPUT DRIVER
surplus market from vendors such as Murphy’s Surplus Warehouse. 600-ohm line driver outputs instead of an AF power amp.
Although surplus SEM-25 radios are not yet very common in the U.S., some have recently appeared on the U.S. This is one of the first amateur band receivers to incorporate a selection of the SSB mode of operation. The SEM-25 is a West German short-range tactical vehicular VHF FM transceiver which was introduced in the 1960’s, and was apparently used until at least the 1980’s. Selectivity choices include AM, CW or RTTY and SSB reception with mechanical filter selection in the 455 kc IF stage for optimum bandwidths. The signal from a type 70E-24 VFO is beat against the variable IF to produce a fixed second intermediate frequency of 455 kc. The dual conversion design utilizes a crystal controlled (fixed) high frequency oscillator and a variable first intermediate frequency (IF). The Collins 75A-4 is a dual conversion amateur band receiver covering the 160, 80, 40, 20, 15, 11, and 10 meter bands. * Note: Tube variations depending on vintage. Collins Radios - Collins 75A-4 Receiver Slide 3 of 8
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