[TenTec] "Upgrading" an Omni V or VI

[John CRUX]

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