SB-303 LMO Problem

[W6CUX]

You need a 50 ohm load on the LMO output jack in the back. I don't have 
the manual but it's there someplace.

 73, Stu W6CUX.


Pat Bunsold wrote:

>I finally got this junker SB-303 to play and it seemed to work well, 
>until I turned the dial up.  All the voltages are correct, which is 
>the 10V, but at dial settings above 100 khz, the LMO takes off and 
>starts to oscillate in funny ways.  I disconnected it from the Mixer 
>and watched it on a scope.  in the 0 to 100 khz region, it is fine.  
>I know it is not 0-100, that is just the dial reference.  Looking at 
>the cams, all the cams are fully CCW until you reach the 100 khz 
>mark, so it may have something to do with that.  It completely freaks 
>out at some frequencies, taking off and providing a white noise type 
>of effect. The sine wave has multiple ringing and very fuzzy.   Returning it to below 100 khz and it works fine with a 
>clean pure sine wave.  What could be wrong?  I know the LMO must be 
>defective, but What in the LMO is defective?  Since these go for a 
>MINT on Ebay, I will have to tear this apart and try to fix it.  Is 
>it the transistor or FET that is freaking out or something about the 
>LMO Coil?  I saw another one listed on Ebay today that had the same 
>problem.  Works fine 0-100 Khz and then dies.  Anyone have any 
>ideas???
>--
>Pat Bunsold WA6MHZ
>San Diego Section Manager
>Curator, Crest Radio Museum
>
>
>  
>

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