Robert Ladden <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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The 'A' at the end of the tube number means that the filament will
heat up within 11 seconds. You can ignore the 'A'.
The Precision 612 is a basic emmisions tester. It will not find all
bad tubes. I had a tube test great on my Eico 625 tester but bad on a
more advanced Jackson 648A tester. The Hickok mutual conductance
testers are supposed to be the best.
You can find more complete charts for the Precision 612 at
http://www.vacuumtubes.com/manuals.html but I don't know if I would
put more money into that tester.
I had to add a 9 pin Novar socket (and related wiring) to my Jackson
648A to test 6JB6 and 12JB6. Only the "newer" testers (after 1960)
can test those without upgrading it.
A good discussion of tube testers is at
http://www.tone-lizard.com/Tube_Testers.html
A lot of good info there. Tube testers are still used heavily by audiophiles.
73,
Bob WW3QB
At 09:20 AM 12/28/2007, you wrote:
"Rich Carter" <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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I'll have to confess that my experience with tubes is limited. By the time
I studied electronics, tubes were no longer covered. I've restored a few
old receivers mostly by tube substitution. I appreciate some pointers from
those more knowledgeable.
I have a Precision 612 tube tester, and I've used it to test some tubes.
Most of the TR-3 tubes used are not shown on the scroll list for the tester.
In particular, the 12JB6 PA tubes are not listed. Thought I realize that
the best place to test tubes is in the actual circuit, I think there are
still uses for tube testing. I thought I might be able to use it to match
the PA tubes. A search on the internet doesn't find settings for the
missing tubes. Does anyone know how to determine tester settings for
unlisted tubes?
Does anyone have a tube substitution list for Drake tubes? I saw such a
list for Swan rigs, but I've not found one for Drakes. If I could find
substitutes numbers for missing tube settings, I might find settings listed
for an equivalent tube.
Also, some of the tubes used in the transceiver have almost the same number
as listed tubes in the scroll list, but have an A on the end. As an
example, no 12BY7A has settings listed, but a 12BY7 is listed. The same is
true for the 6AU6A. Does anyone know what the A suffix means?
Thanks in advance
Rich KE1EV
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