Steve, thanks very much for the ideas. ?Inhad not thought of what you just pointed out!! ?I could get an 18 V source and connect it via resistor to the HV point and solve that…. ? ?maybe I can try that tomorrow. ? Thanks!!
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On Oct 31, 2023, at 19:57, Steve Beckman <ssteven3sb@...> wrote:
?Gordon - sorry, I don't have a V2. Maybe some day...
Your tests appear to demonstrate that a reverse bias needs to be applied to the switching diodes to turn them off (or reduce their junction capacitance.)
Note that because of D20 and D21, the reverse "HV" bias will be LESS than the forward bias if one of the low pass filter sections is NOT turned on. Only by turning ON (selecting) one of the filters will there be a voltage drop across R201/R202 and R203/R204, which will allow the reverse bias voltage to be higher than the forward voltage.
Do that, then try bypassing L22 at R203/R204.
73; Steve, N3SB
