From: Garey Barrell 
Subject: RE: [Drakelist] Re: Passband tuning on R4C with Sherwood 600Hz
  roofing filter


Bruce and others -

I have to admit to being doubly prejudiced on this subject.  I am NOT a 
"serious" contester, which is where narrow roofing filters are a distinct 
advantage and worthwhile.

1.  I actually prefer to have a wider filter on CW, normally using the 1.5 
kHz position or wider filter as available.  Over the years of CW operation 
I have developed a pretty fair "internal" filter to enable me to separate 
closely spaced signals.  Probably originating in my early use of a BC-454 
surplus aircraft receiver on very crowded Novice bands in the 50's.   The 
IF in that thing must have been 30 kc wide.  You could listen to the entire 
Novice band without moving the dial!  My R-4C's both have the 500 and 250 
Hz filters, but I like to be able to hear what is going on around my 
frequency.  Passband tuning allows me to drop a particularly annoying 
signal off whichever filter slope works, and the Notch allows me to dump 
another one.   If two signals are too close together for me to separate 
them, (50-100 Hz), then a narrower filter isn't going to help anyway.

2.  I like to keep vintage gear "as it was" rather than try to
make it into 
something it wasn't.  Even that broad as a barn BC-454 is of more value to 
me as a BC-454 than as the conglomeration of electronics I eventually 
turned mine into back then.  The IF was at 1415 kHz, so I stuck a piece of 
hookup wire down inside the last IF can and wrapped the other end around 
the loop antenna on the back of my clock radio.  Double conversion with 
passband tuning!!  A little later I added a Heath QF-1 Q-Multiplier to the 
clock radio IF, (an interesting experiment since the clock radio was 
AC/DC,) and eventually added a BC-453 "Q5er" onto the clock radio IF for 
triple conversion, dual passband tuning!  Pretty advanced for the 50's!

It's kind of like putting a Chevy V-8 into a Jeep.  What you end up with is 
a compromise that isn't a Chevy and isn't a Jeep.

I still hope there is a special place for the guys who drilled the hole 
through the Johnson Viking on the Rangers to add that toggle switch for T-R 
control...!

73, Garey - K4OAH
Atlanta

At 12:24 PM 1/4/2003, Bruce Marton wrote:

>On one of my R4C's, I have the Sherwood CW 600 filter installed, along
>with the GUF-1 filter.  On the back of the rig in the spare holes there
>are a couple of RCA jacks installed.  From there I have a line to an
>external switch to cut the 600 hz. Filter in or out depending on what I
>need.  With this set up, I have the best of all worlds.  The jacks on
>the back go to an internal relay to switch the filter in or out.
>73's
>Bruce K1XR


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