Fw: [AMRadio] re: Apache audio not good

[rbethman at comcast.net]

----- Original Message -----
From: "russ dworakowski" <wb3fau at hotmail.com>
To: <amradio at mailman.qth.net>
Sent: Sunday, April 14, 2002 4:23 PM
Subject: Re: [AMRadio] re: Apache audio not good


> 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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