#83 Rectifier

10/15/2007 11:11:01 PMJeff S.

I pulled the rectifier tube (#83) out of my B&K 700 tube tester. About one-third of the coating on the plates has flaked off and there's a really pretty bluish-white glow from inside each of the plates when I test it on my Hickok 533. The tube tests OK, but I'm thinking that may be deceptive because of the poor condition of the plates. Are the plates supposed to glow?

Also, is it safe to replace the existing 20 mfd caps with new 22 mfd caps? Fudging a little on the cap rating works OK in a radio, but is it OK in a tube tester?

This tube tester worked pretty good until just recently when it started giving me questionable/bad readings on various tubes. I tested the same tubes on two other tube testers, which gave comparable good readings. I don't know if the rectifier tube has anything to do with the decline in accurate readings (bad electrolytic caps might), but I suppose anything's possible.

Jeff S.

10/16/2007 12:53:52 AMNorm Leal

Hi Jeff S

The 83 is a mercury vapor rectifier. It's supposed to glow blue between the filament and plate.

The 83 probably ok since it tests good.

It's ok to use a 22 mf in place of 20 mf. Just be sure voltage equals or is higher than the original.

Norm

:I pulled the rectifier tube (#83) out of my B&K 700 tube tester. About one-third of the coating on the plates has flaked off and there's a really pretty bluish-white glow from inside each of the plates when I test it on my Hickok 533. The tube tests OK, but I'm thinking that may be deceptive because of the poor condition of the plates. Are the plates supposed to glow?
:
:Also, is it safe to replace the existing 20 mfd caps with new 22 mfd caps? Fudging a little on the cap rating works OK in a radio, but is it OK in a tube tester?
:
:This tube tester worked pretty good until just recently when it started giving me questionable/bad readings on various tubes. I tested the same tubes on two other tube testers, which gave comparable good readings. I don't know if the rectifier tube has anything to do with the decline in accurate readings (bad electrolytic caps might), but I suppose anything's possible.
:
:Jeff S.

10/16/2007 6:47:46 PMThomas Dermody

Check your resistors. My EICO 625 used to give bad readings on the #2 setting. It was due to drifted resistors.

10/16/2007 10:11:54 PMJeff S.

I noticed in the schematics that there are significant resistors that are in the grid emission check circuit. I'll go after those first.

I ran several comparisons tonight between my Sencor TC-162, Hicock, and the B&K after swapping out the caps. It still measures some (but not all) of the tubes at lower quality. I pulled the chassis out of the box and looked at the rectifier tube (83), and noted that it does not have that bluish-white glow under the plates like it did when I tested it on the Hicock. If it glows when being tested, shouldn't it also glow when it's in use in the B&K? There are a lot of particles of some kind of coating all over the inside of the tube that have fallen off of the plates. The other tube in the set (6-something-or-other...I don't have the book in front of me right now) tests almost 100%.

10/17/2007 12:09:56 AMThomas Dermody

Silver balls are mercury, if those are the particles you talk about.

10/17/2007 12:51:13 AMPeter G. Balazsy

:Silver balls are mercury, if those are the particles you talk about.
:
:T.

Unless it's the Lone Ranger ...he only has silver bullets not the other.

10/17/2007 9:30:24 AMThomas Dermody

LMAO

::Silver balls are mercury, if those are the particles you talk about.
::
::T.
:
:Unless it's the Lone Ranger ...he only has silver bullets not the other.

10/17/2007 7:44:09 AMJeff S.

The plates are coated with some kind of dark material that has flaked off, kind of like old paint.

Jeff

:Silver balls are mercury, if those are the particles you talk about.
:
:T.

10/18/2007 3:54:13 PMBill G.

:The plates are coated with some kind of dark material that has flaked off, kind of like old paint.
:
:Jeff
:
::Silver balls are mercury, if those are the particles you talk about.
::
::T.

Hi Jeff,
Tubes weren't made to be pretty. I have found that they are only occasionally the problem in sets, too. Problems are far more often capacitors and resistors. Look at those first.

Best Regards,

Bill Grimm