THE CIRCUIT SHOWN BELOW IS THE UNIDEN ROGER BEEP CIRCUIT USED ON THE COBRA 148GTL-DX, SUPERSTAR 360FM, PRESIDENT GRANT-DX, AND MANY OF THE OTHER EXPORT CLONES (especially Galaxy).
TR 33 is the roger beep oscillator and operates at 1200 - 2000 Hz ( depending upon component values). When the unit is keyed up, the oscillator turns on, but it's output is shorted to ground thru diode D92. When the key is released, oscillator output is enabled, and the R206/C270 combo holds the unit in transmit for a few milliseconds and the beep is broadcast.
Change the values of C154 and C156 to vary the beep frequency. Change the value of C270 to shorten or lengthen the beep. To transmit a continuous tone, install switch S2 as shown, Opening S2 prevents the oscillator output from being shorted out, and the unit will transmit a continuous tone whenever the key is down. This is handy when aligning the radio's transmit section. Also helpful for tuning up tube amplifiers, matchers, or just plain agitating.
- 399