Glen,
Looks like that would work...? To do your test you built it too, good.
Now the challenge.. add realys to switch it in place to repealce the 9 element low pass filter
for above 20mhz.? You can use TX-A? the control as that is in active for above 21mhz.
the logic is if KT1 is not picked activate your relays to inert the new filter where the
low pass was.? The collector of q17 is at 12V when that is the case and that can be
used to drive a 2n3904 hooked up like Q17 too activate the added relays.''
For testing insert it with wires(coax) and see if the spur at the output is below -43dbC.
FYI I'd move the corner frequency up to about 22.5mhz because its tempting to try 15M
that way save for the spur for that is 23.5ish? (45- |21.2 to 21.45|= 23.8 to 23.55mhz).
Allison
