(Ray D. O'Mann) wrote in message . com...
(Ray D. O'Mann) wrote in message . com...
Hi Folks!
Dumb Question #1: How can I test vacuum tubes without a tube tester?
Namely, 6AK6, 6BE6, 6HR6, and 12AX7.

Dumb Question #2: Is there a solid-state equivalent to these tubes?
They are from an old Knight Star Roamer that keeps dying.

Dumb Question #3: Is the above worth doing?

Thanks for your help.~~Ray

Hi All!
Thanks a bunch for the tips, tricks, and advice. It is VERY
appreciated. Everything always tests OK out of circuit and I've been a
bit reluctant to do the in-circuit testing since all I have is a DMM.
The shop where I was testing my tubes now charges a fee for using
their tester.

Find a tester. You can get them cheap, or even free. I have two good
ones, both that I got free. One is a Sencore Continental, and the
other is a hickok 539c...I use the sencore the most as I got it first
and got used to it, and it works well. But the hickok is supposed to
be pretty good too. I see them on e-bay a lot. Ham flea markets have
them laying around sometimes.

With everything that you all have posted for me, I
believe I can get it to work right. I hope. To answer some of your
questions, it just quits. I test the tubes, then I check the caps,
diodes, connections, etc., plug it back in and it works for a day or
two and then quits. Any thoughts?~~Ray

Could be a cold solder joint. Could be a cap flaking out when it gets
hot enough. Could be a dirty bandswitch. Quite a few things...When it
goes out, is it instant like a bad connection, or does it slowly start
to get lower, and then eventually fade out? The latter would be more
likely with a cap or tube. If it does that, you can use chill spray to
cool the caps down and find the flaky one if it's a cap. I'd try to
find some extra tubes so you can sub them out. 6BE6's are super common
and should be cheap. Ax7's common, but more usually. Depends on the
brand...The other two are less common and may be a bit harder to find.
I hardly ever see HR6's. You can find most tubes new on the web, and
e-bay is a source also for both new and used. I see some deals on used
tube batches sometimes. MK

I test the tubes, then I check the caps,
diodes, connections, etc., plug it back in and it works for a day or two and
then quits. Any thoughts?~~Ray

If it quits relatively slowly, I'd check for over value resistors, especially
in the screen and cathode circuits. Also check those in series with the plate
circuits (decoupling resistors) as well as in the AVC and oscillator control
grid (high value types).

Heck. Just go through, with the radio disconnected, and check all resistors. If
any measure more than 10% higher than they are marked, replace them.

By the way... I believe you listed all the tubes as glass miniature types, but
intermittent filaments in metal tubes can be checked by feeling for warmth.

73,
Bill, K5BY