[AMRadio] re: Apache audio not good

[russ dworakowski]

Bill,  people have been  doing  mods  to  Apahes for  years with good
results.  The neg.  feedback loop is a simple  mod,  just  2 parts,  be  
careful  though,  you  will be  working  with  High  voltage.  You will need 
a  transmitting cap rated for  about 1kv  and a 500k  1 watt
pot.  Look for  the  mod transformer secondary winding on a  terminal
strip.  Yuo  will find an  unused  500 ohm  tap  by itself, doing  nothing.  
Here is  where you  connect one side  of that  hv cap.
Now  wire a  jumper  on  the  pot to  make  it a   rheostat  [2 terminals]-  
now  connect  one  side of the rheostat   to  the  unused
side of HV cap.  The  other side  of the rheostat  goes to the  cathode  of 
the 12BY7  audio driver  tube.  Start  out  with  the  rheostat  fully 
closed,  put the  transmitter on the  air.  Slowly  open  the  pot.  You  
will reach  a  point  where  you  will  hear
the  audio  feedback,  turn  it  back  slightly,  That  should be it.
The  cap  should  be about a 0.1uf.  Yuo  will get  improved audio
reports!  Russ


>From: "Bill & Claire Zaiser" <bzaiser at bellsouth.net>
>Reply-To: amradio at mailman.qth.net
>To: amradio at mailman.qth.net
>Subject: Re: [AMRadio] re: Apache audio not good
>Date: Sun, 14 Apr 2002 11:07:40 -0400
>
>Russ,
>Could you please give us the details concerning installation of a
>negative feedback loop?
>       -Bill Zaiser
>
>On 13 Apr 02, at 18:48, russ dworakowski wrote:
>
> >
> > Hey folks,  the  control behind  the  key jack is  not a limiter, it
> > adjusts  the  clipping  level!  You  will find  2 or 3  coupling  caps
> > in  the speech amp  that are  500 pf,  these  need to be  removed  and
> > replaced  with  .01 to  .05  uf  coupling  caps.  The  biggest  bang
> > for the  buck  improvement  comes  with  installing  a negative   
>feedback
> > loop from  the  mod.  trans.  secondary [500 ohm tap]  to
> > the  cathode of  the  12BY7 driver tube.  Ask  and  I will send  more
> > details.  Russ
>
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