[AMRadio] re: Apache audio not good

Tue Apr 9 12:59:24 EDT 2002

Hi Ron,

Well, I had an Apache years ago and did make some minor mods to it.  I
bypassed the speech clipper, eliminated an audio stage and increased the
values of a few coupling caps to get better low end.  This was years ago
and I may have given my notes away when I sold the rig.  I picked up
another Apache last Summer, so I'll be looking at the issue again.  You can
probably get decent audio by doing like Pete said: keep the level low
enough to avoid clipping.  The D-104 crystal mic element needs to look into
a high impedance (> 1M probably) to get decent low end.  I don't know the
input impedance of the built in preamp, but it probably isn't that high.  I
ended up bypassing the preamp and running the mic directly into the rigs
that I use it with.  Most of those have mic amp grid resistor values of 1M
to 4.7M or so and that helps.

Have fun -- it doesn't hurt to play.  If you make reversible mods, there's
nothing lost.  Even if the mods are more permanant, it is your rig after
all!

Good luck and 73,

Ed N3CMI

                      "Ron Samchuk"                                                                                                  
                      <samvideo at escape.c        To:       <AMRadio at mailman.qth.net>                                                  
                      a>                        cc:                                                                                  
                      Sent by:                  Subject:  [AMRadio] re: Apache audio not good                                        
                      amradio-admin at mail                                                                                             
                      man.qth.net                                                                                                    

                      04/09/02 11:35 AM                                                                                              
                      Please respond to                                                                                              
                      amradio                                                                                                        

Hi again...
    Thanks for all the advice and suggestions received so far concerning
    the Apache and Mohawk.  I had one person asking me to be more specific
    on what I was prepared to do.  I don't want to make major changes or
    modifications, but simply have a good signal with acceptable AM audio.
    For example, I used the Apache last night... power output was fine,
    everything loaded up OK, but I could tell on the scope that the pattern
    was not good.  It looked like vertical scratches rather than a nice
    envelope.  Contacts tried to be nice, but did say it sounded very much
    on the high frequency side, with one person saying that he could
    receive me better on ssb setting.  The microphone used here is an
    amplified D-104; being careful not to have too much audio gain.
    Something I have not done is grounded the rigs so there is a
    possibility of course that perhaps rf is getting into the audio.
    So any suggestions as to what to check or mods would be appreciated.
    Thanks in adance for any comments.  Ron VE4SR (VE4 Super Rabbit)

--- StripMime Report -- processed MIME parts ---
multipart/alternative
  text/plain (text body -- kept)
  text/html
---
_______________________________________________
AMRadio mailing list
AMRadio at mailman.qth.net
http://mailman.qth.net/mailman/listinfo/amradio