On Mon, 08 Sep 1997 12:43:48 +0000 Jim Henderson <jhenders@zianet.com>
writes:
>Esteemed Reflectees:
>
> Don't see much commentary on the L-4B, but mine just cratered.
>Was
>in standby when a crack and long fizzle sound came out of the RF
>section.
>The grid resistor opened up, and the meter needle pinned to the left
>(minimum) direction.
There is no grid resistor as such in the L4B Jim. Which part opened up?
In the standy position, the only path thru the grid meter is thru the
bias supply return lead and then thru the 1 Ohm to ground. Since this
would be a reverse of normal flow I would start looking in the PS.
>
> I happened to be looking right at the RF section when this
>happened,
>and saw no arc or tube glow. Anybody know if this is a common failure
>mode?
>Since the tubes were biased off at the time, parasitics don't seem
>likely,
Only during a full moon.
73....Carl KM1H
>and I ohmed the tubes and see no shorts.
>
> I had a diode stack go out on this unit once, but never had a
>RF
>section pronlem in the 12 years I've had this amp.
>
>73 de Jim, KF7E
>
>
>
>Jim Henderson
>
>jhenders@zianet.com
>jhenders@tdrss.wsc.nasa.gov
>kf7e@k5di.nm.usa.noam
>
>
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>
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