This preamplifier for the 6 or 2-meter range was obtained from an American documentation from the 1980s. FETs can be modern equivalents and no information about the coils is given.
This circuit triggers the LED when the monitored battery voltage drops below 9 V for 12 V...
We found this circuit in a Radio Electronics from January 1967. The SCR is already the C106, which...
This power source with silicon diodes at a time when valves were still used was found in Radio...