[R-390] Solid State Ballast 'quirks'?

[Bob Camp]

Hi

Just about any component can be intermittent. The ballast should be 
pretty easy to check based on weather the filaments light up or not. If 
I was going to bet on the cause it would be a loose connection early on 
the IF strip or at the tail end of the RF chassis. The key clue being 
that you still have static when the signal goes away. If the 
intermittent is late in the IF strip then the radio just goes quiet. 
That does not rule out the conversion oscillators, but it includes a 
few more parts ...

If you have a copy of a manual (there are several on the net) they have 
some pretty good voltage at a point troubleshooting data in them. It's 
good to have a VTVM to do the measuring with. If you don't have one 
already they are a pretty darn cheap these days. If you use a DVM then 
you may have to adjust some of the numbers a bit. Another good thing to 
get a hold of if you don't have them already is a set of tube 
extenders, it makes things a lot easier to measure. You should be able 
to get the extenders for $20 and the VTVM for $30 if you are in a hurry 
or quite a bit less if you shop around.

Hope that helps.

	Enjoy!

		Bob Camp
		KB8TQ


On Jun 2, 2004, at 2:10 PM, Mikek wrote:

> Howdy
>
> I have a Collins 390a that has a solid state ballast
> replacement that I got as part of the restoration.
> Sometimes, while listening, the station will suddenly
> 'go away' and just have static.  I noticed some of what
> appears to be 60 cycle hum in the audio.  The Tuning and
> BFO does nil but the AF section is still working and selecting
> the various filters has the noticeable 'audio' so I wonder
> if the 'balast' cut off.  I power off the radio and let it
> sit and sometimes the set comes back for a while then goes
> dead.  Other times, I let the radio sit overnight and the
> next day all is good - SO, I know this is an intermittent - should
> I zero in on the solid state ballast first - I suspected that
> unit since the only thing that seems to go away is the tuning/bfo
> - any one seen this before??  Any other places to look while
> troubleshooting?
>
> Thanks es 73
> Mike AA9IL
> -- 
> Caution, Distance Ahead
> CoreComm Webmail.
> http://home.core.com
>
> _______________________________________________
> R-390 mailing list
> R-390 at mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/r-390
>