I was not thinking about checking the continuity in the tubes themselves
when I balked at opening up the amp deep enough to check the continuity
at the sockets! I didn't connect those dots initially.
So anyway, you guys straightened me out. Here's how it went:
Check tubes cold. One tube has a grid to cathode short. Problem solved.
Put two new (used) tubes in, amp runs like it should.
Thanks!
73 - Mark N5OT
On 3/19/2020 7:31 PM, Mark - N5OT wrote:
This is getting more and more exciting all the time. Stay tuned. So
to speak.
73 - Mark N5OT
On 3/19/2020 5:45 PM, VE1DT wrote:
Hey Jim & Mark,
Stayed failed to me means that the sucker is welded.
How do I know this for certain ,you ask? My new AL80B became
intermittent within the first few months after getting it. The grid
meter was pegged negative at the zero end. After a few more times, it
finally stayed failed. I pulled out the tube and measured a short on
the pins of the tube. Easy peasy. I had a VOM, but no spare tubes to
swap with.
I am sure there are intermittent cases out there as well.
--
Gerald, VE1DT
>/Grid to cathode short & ?stayed failed? means you just need an /
>/ohmmeter. No need to swap tubes, etc./
>
>/Gerald, VE1DT/
>
## Nope. The grid to cathode short only happens with tube fil
lit..... not when cold.
When cold, both a HI pot tester.... and also a megger wont work
either.
Jim VE7RF
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