[R-390] Two questions

[JMILLER1706 at cfl.rr.com]

Hopefully the narrower filters haven't gone bad - did you replace the 
coupling capacitor in the IF unit that has a history of failing - and 
destroying filters?  And if you go to a narrower filter, you may need 
to tweak the tuning to center the signal in the narrower filter 
passband - should be obvious but just wanted to mention it.

On the 7 mc sensitivity, this was discussed a few years back on the 
list and the thought was that the reduced sensitivity on that band was 
normal for the 390a.  I have two which show a 1-2 dB reduction in 
signal (calibrator) level on that band.  Not sure why, apparently 
something in the Xtal Osc or RF design.  A complete realignment for 
that band may help some.

----- Original Message -----
From: Keith Densmore <densmore at idirect.com>
Date: Thursday, April 12, 2007 9:10 am
Subject: [R-390] Two questions
To: r-390 at mailman.qth.net

> I have a Imperial unit which I will be getting into shortly. It 
> works well now, and the PTO is all re-aligned and stable.
> I notice a couple of problems with it, and I wonder if anyone on 
> the list has had these and/or has any thoughts. Forewarned is 
> forearmed!1/ Sensitivity drops noticably going from the wider 
> mechanical  filters to the narrower ones. The level meters are out 
> of it but its probably more than 10-15db from 16 to 2 kc. This is 
> actual signal loss not just noise loss of a narrower filter.  
> Anything to look for?
> 
> 2/Lower sensitivity on the 7 mcs band compared to all other nearby 
> bands. Does not appear to be the band switch, it makes positive 
> contact on all ranges.  I thought might be alignment of the  7-24 
> mcs crystal but it peaks nicely with its trimmer. Any thoughts?
> 
> Thanks All, 73,
> Keith ve3ts
> 
> 
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