Tube Amp Archive

You may find that it has lower thermal conductivity than aluminium too. That is, if you count on it for heat sinking considerable power in small areas.

Additional capacitance, including that of a Zener or TVS, will nominally increase the required drive current at high frequencies. There is more than sufficient drive current to feed 360pF.

If you're talking about an AC line filter cap, I strongly advise you to replace it with a less-likely-to-become-lethal modern safety cap. Here's an easy read as to why: http://www.justradios.com/safetytips.html

BTW: if there is any DC offset, perhaps due to some cosmic GNFB connection or whatever, then some DVMs may read incorrectly. Also, just to give you a heads-up in future work, most DVMs freak out when RF (such as from oscillation) is present.

Your trace is not across the whole width of the screens you likely have some electrolytic caps drying up in the scope, which is a issue I 've yet to get to in one of mine, so I shouldn't talk! A cap ESR meter will make short work of the issue with out un soldering a thing most likely . If you look ...

With one hand in your pocket, try wiggling the tubes when it occurs to see if it may be caused by oxidation of the pins/sockets. If so, a little (not a lot) of DeOxit is your friend. I agree that it may be contamination causing errant behavior. If there is significant (i.e.: an oily residue or tobac...

www.renovatedradios.com/articlePages/H500%20Restoration%20Guide.pdf A very groovy man named John "badrestorer" has taken a great deal of time to generate tutorials on radio repair. On page 50 is a bit on re-stuffing can caps. The spiral that I talk about is on page 54. The whole document is right fa...

Cutting the old cap free first can help minimize the strain on lugs. Another way to do it would be to cut the old cap free but leave some of its leads behind. Then the new cap's leads are spiraled around a tiny screw driver or similar tool to form two tiny cylinders and the old leads are then each c...

My mistake! I should know better. Caps in series do not add together. Instead, it is a "reciprocal of the sum of the reciprocals" thing. The voltage withstanding is increased. The total capacitance is within a 5AR4's capabilities. Boy, do I feel silly.

http://www.valvewizard.co.uk/cathodyne.html
It is, and here's a good description of it:

D'oh! Duplicate post.

That is a grid-leak bias configuration. The cathode will be above ground due to I*R drop on the 30 k Ohm resistor and the grid will be slightly (~1.5V?) negative when measured relative to the cathode.

Check the coupling caps and grid-leak resistors at the phase splitter.

The resistors serve to accomodate each capacitor's voltage rating.
Edited this post.

Mea culpa - see post below.

It may well be appropriate to refer to MIL-HDBK-1131B rather than to "Larry." Nothing against Larry, never met him myself. However, procedure, acceptance/rejection criteria are all well documented. Here's a link to a copy:
http://www.dscc.dla.mil/Downloads/MilSp ... hb1131.pdf

For the occasional extended extreme (i.e.: full rated load power for more than just a few seconds) test I have placed dummy loads, heat sink and all, in distilled or DI water. However, there is a limit to how much heat the load itself can tolerate due to the thermal resistance between the actual con...