SB-102 problem

[Bob Burns]

Hi Brian
 
Two things to try:
 
1. When you turn the RF gain control fully anti-clockwise does the S meter  
go to full scale deflection? If it does then there is nothing wrong with 
the  S-Meter circuitry and the DC control of the IF amplifiers as this is what 
drives  the S meter.
 
2. With the RF gain fully clockwise and the AF gain control turned up to  
about 30% of full scale is the background noise clearly audible or very  low? 
If it is low then you have a problem with the RF/IF gain and I would switch 
 the 102 off and measure all of the fixed resistors. These rigs run fairly 
warm  and after 30+ years you will probably find one or more that are way 
out of  specification or have actually failed. I have never yet had a silver 
mica or  disc ceramic capacitor fail but  have had some electrolytics fail.
 
There are some shared and some separate circuits between Rx and Tx so you  
may find that the Tx power is also down but do one thing at a time. I assume 
 that all of the rails from the power supply are correct?
 
73

Bob 

G3OOU
G-QRP  6907
Joint site with Crystal Palace Radio & Electronics Club: _www.g3oou.co.uk_ 
(http://www.g3oou.co.uk/) 
My technical site: _http://www.qsl.net/g3oou/_ (http://www.qsl.net/g3oou/) 

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