Add On S-Meter driver for Hamtronics® R series receivers
Concept:
To provide an s-meter output proportional to signal input on receivers
that use the Motorola MC-3357 or MC-3359 style IF amp/limiter/detector.
The circuit could also be used on other receivers by connecting the
circuit input to the receiver's last IF stage.
Description:
The circuit described here deals with providing a DC voltage from near
zero to just over 5 volts depending on signal input to allow a controller
or local meter to be driven. This circuit will drive the ACC controller's
s-meter input directly. A calibration pot is provided to allow the user
to set the s-meter calibration as desired.
Construction:
Construction can be simple breadboard wiring as the whole circuit will
fit on Radio Shack's 1 7/8" by 2 7/8" breadboard. The IC should be mounted
in a socket to allow easy replacement. Use a 7808 voltage regulator or
a local 8-9 vdc if available to power the circuit. The circuit does not
load the receiver in any way and will not degrade the receiver's performance.
Try to keep the lead from the IF amp/limiter/detector mixer output as short
as possible. The detector diodes can be 1N914 or 1N60.
Circuit designed by Kevin K Custer W3KKC