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[wxsig] MODEM2 Low TX audio

Sct599 at aol.com Sct599 at aol.com
Wed Feb 15 18:00:16 UTC 2006

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?
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?

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