I still run my Omni-V.9 and I admit to having put a heap if INRAD filters in
there. Yes they work fine. But, and its a big BUT, after an awful lot of use
on the LF bands, there is little point in spending a raft of dollars on
filters if you still have the relatively poor IMD performance of the standard
product detector. I still have that despite all the expensive, cascaded
filters ahead of it.
Some years back there was an article published on this. And there was a fix
for the Omni-VI in the shape of an add-on board with a much less vulnerable
IC detector using the high level mixer chip developed by Plessey, the SL6440,
(sadly now discontinued.)
I managed to get the circuit and a couple of the chips, but shoehorning it all
into an Omni-V is not trivial and I chickened out ..
In short, adding expensive filters to an old radio does not necessarily cure
everything. You do not end up with a Sherwooded R4C, or an Orion.
You end up with an expensive Omni.
I also have a 40m INRAD roofing filter I can switch in. It does cut out the BC
and other crud above 7015 and the commercial garbage below 7000. But it does
not fix in-band overload. .
John G3JAG
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