SB310 problems

[Bob Burns]

In a message dated 16/10/2009 20:59:11 GMT Standard Time,  
ddswl at CENTURYTEL.NET writes:

I have  an SB310 receiver with two dead bands (3.5--26.9). I checking 
voltages  when the probe touches pin 1 (grid) of the RF, ALL bands come to 
life  & work FB with an 18 inch clip lead to the grid.
Resoldered all RF tube  and band switch points, checked caps & res & 
checked 
wiring, all  is correct and so are voltages.  What next?? Any ideas?? 
Tnx--Doug  W7LNB
ddswl at centurytel.net 


Hi Doug  

My initial thoughts are that the RF stage is oscillating or there is a  
problem with the bandswitch on those two bands and you are disturbing the 
wiring  or switch sufficiently to 'fix' the problem. I rebuilt an SB310 and some 
of the  wafers were extremely tarnished and intermittent.  Try rocking the  
bandswitch back and forwards slightly on those bands and give it a clean 
with a  modest amount of an electrical switch cleaner.
 
You might also check that the band oscillator works reliably on each  band.


 
73

Bob 

Bob F Burns
Amateur  radio callign G3OOU
G-QRP member No. 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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