[ARC5] ARC-5 Audio Comparison, Stock vs. "CQ-VooDoo"

[Richard Knoppow]

----- Original Message ----- 
From: "Clare Owens" <clare.owens at gmail.com>
To: "Jay Coward" <jcoward5452 at aol.com>
Cc: <arc5 at mailman.qth.net>
Sent: Sunday, October 21, 2012 12:27 PM
Subject: Re: [ARC5] ARC-5 Audio Comparison, Stock vs. 
"CQ-VooDoo"


>I just paged through my copy of the Q Command Sets 
>publication and I
> couldn't find any mention of adding an outboard audio 
> stage.  I did find,
> on page 23, the fateful words"The first step is to strip 
> the chassis" in
> the article on War Surplus for Civil Defense.  I had to go 
> wash my hands
> with Holy Water after touching that page :-)
>
> Clare
>
    My main experience with modifications was my BC-779. 
When I got it I found that the RF section had been modified 
according to a CQ article. I don't remember now if the 
fellow had also modified the audio section.  The RF mods 
were used common cathode pairs of dual triodes, 6SL7s I 
think. I don't remember how he got the grid leads on. In any 
case I unmodified it and returned it to original. At various 
times I tried modifying the RF and mixer stages but 
eventually returned it to original. About the only really 
useful mod was to add a voltage regulator to the oscillator 
and _that_ was not in the article. Unmodified the receiver 
works very well other than using rather noisy tubes for RF 
amps and mixer. I found that trying to use base extenders to 
get the normally cap connected grids on  without drilling 
the chassis caused capacitive loading which tended to 
broaden out the RF response. Not desirable at all.  The 
original tubes despite being noisy don't load the RF 
transformers much. I still have this receiver but I think 
now it needs all new caps.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com