Would somebody like to suggest the preferred means (a sketched circuit?) for checking the ceramic filters (preferably using the sort of low-grade test kit I own)?
I did a very crude check on my HRO crystal, simply putting it in series between an old sig-gen and an old scope
and did see the scope respond at 455kHz, but I suspect that a slightly more elaborate set up would have been better. I've seen one suggestion to put a 10R resistor in series with the crystal so that the crystal current can be observed, might be better?
In terms of one filter not suiting all modes, yes, but the Hammarlund switched loading of a single crystal seems to have been a good attempt at a "filter for all seasons". If the directly-wired version of the HRO crystal, devoid of any connections to short it, comes good, the Ham. filter might still prove a good option and is not a
drastic re-work of the existing HRO circuit (and still be able to listen to music).
B