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[wxsig] MODEM2 Low TX audio - Fixed

John Koster w9ddd at tapr.org
Thu Feb 16 10:40:47 UTC 2006


So, now the question is should we add something to the manual for radios 
that require higher drive to the mike input?

-- 
73,
John, W9DDD

On Thu, 16 Feb 2006 Sct599 at aol.com wrote:

>  
> Thanks Joe.  Works great now.
> 73,
> Scott
>  
> In a message dated 2/15/2006 12:52:41 P.M. Mountain Standard Time,  
> wa5vms at tapr.org writes:
> 
> Sct599 at aol.com wrote:
> > Hello Group:
> >  
> >  Adding a MODEM2 to my original T238.  I am connecting it to a ICOM   
> IC-2100 
> > which should work with the separate Mic audio (TX audio)  and  PTT lines 
> (not 
> > combined like an HT). The PTT and RX audio  are working properly.  My TX 
> audio is 
> > very low even with  adjusting V100.  The audio does change  with V100 
> >  adjustment but is still too low when even at max.  In my   troubleshooting 
> of the audio 
> > path I have noticed two  things....
> >  
> > 1. R101 is shown as a 10K on the schematic.  However, the instruction 
> manual  
> > and parts list calls for a  100K.  A 100K was provided and is what I  have 
> > installed. I  jumpered past R101 and the audio did indeed increase but not  
> to an  
> > acceptable level. What value should R101 be?
> Change it to a 4.7 K  and the output coupling capacitor from 100 pf to a 
> .1 uf.
> 
> This  should solve your problems.
> 
> Joe
> >  
> > 2. V100 is  supposed to be oriented on the board to match the  
> silkscreening.   
> > However, if you do so, the leads are not oriented   properly.  I reversed 
> V100 
> > from the silkscreening to match the  lead  arrangement and the photo at 
> >  _http://beals5.com/wx/index.htm_ (http://beals5.com/wx/index.htm)   under  
> "How to 
> > build a T238+"  Does the orientation of V100  make a  difference?
> >  
> > Any other ideas?
> >   
> > 73,
> > Scott
> >  _______________________________________________
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> > wxsig at lists.tapr.org
> >  https://lists.tapr.org/cgi-bin/mailman/listinfo/wxsig
> >  
> 
> 
> 
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