From: "Al Parker" 
Subject: Re: [drakelist] R4-B Asymmetrical Sideband Response


Hi Rocco, Tom, et al,
    Let's not confuse the TR-3/4 filters with the R-4A/B series.  The
transceivers have 2 separate, switched, sideband filters at 9.000mc.
Early ones (soupcans in particular) go bad frequently, at least by this
time frame.  The R-4A & B  receivers didn't have switchable filters.  They
do have a single 6kc wide filter in the 5645kc IF.  I suspect Rocco's
problem is with alignment, go thru secn 6.4.4 again.  I've never found
much change reqd in part 8, the wire twist adjustment, but since you
didn't do it, maybe you should, and then go thru it all again, as they
suggest.  I suppose it might be possible for the 6kc wide filter to have
narrowed & be causing your problem, but that's one problem I haven't heard
of before.
    As an aside, there was a well published mod for the R-4A & B rcvrs
using the 2 switchable 5645kc filters from a T-4 (Aor B) xmtr in the rcvr.
I have an R-4A with that mod, and it's super.  Those filters are narrow,
abt 2kc or slightly more, and and in conjunction with the tunable
passband, really cut the QRM.
    Another aside, one of our other Drake "junkies" has just put in a
substiute single 9mc filter in his TR-3 and switches it for use on each
sideband, with great results.  You have to readjust the dial readout for
the different SB, like Swan & Kenwood did, but it's a relatively easy way
to resurrect an otherwise hobbled TR-3/4.
73,
Al, W8UT
New Bern, NC
BoatAnchors appreciated here
http://www.thecompendium.net/radio/
http://www.hammarlund.info


----- Original Message ----- 
From: "Rocco Lardiere" 
> On a related subject, I have a problem on my R4-B that has been bugging
me.
> The LSB response is down several S units from the USB response.  This is
> AFTER a careful alignment of the radio per the manual using lab grade
> equipment, including tweaking the passband adjustments (I have done
these on
> several other R4-X radios with great results).  The selectivity seems to
> work normally, except for the asymmetry.  I did skip para 6.4.4 part 8,
the
> crystal filter "wire twisting" adjustment - could this filter response
be
> related (roofing filter drift, etc)?
> Rocco N6KN
>


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