Path: utzoo!attcan!uunet!ogicse!uwm.edu!csd4.csd.uwm.edu!info-high-audio-request
From: mikes@iuvax.cs.indiana.edu (Michael Squires)
Newsgroups: rec.audio.high-end
Subject: Re: Destructive KT88
Message-ID: <6879@uwm.edu>
Date: 10 Oct 90 18:44:36 GMT
Sender: news@uwm.edu
Lines: 21
Approved: tjk@csd4.csd.uwm.edu

In article <6866@uwm.edu> KLUDGE@AGCB1.LARC.NASA.GOV writes:
>That's it.  I've had enough of crappy Chinese KT88's which suddenly decide
>to pull tremendous amounts of current, opening up the cathode resistor and
>glowing red hot.  This has happened three times on my Citation, with three

This was fairly common ten years ago with the Dyna MKIII and British Gold
Lion KT88's.  The problem was the tube socket which was either improperly
soldered or whose contacts were no longer making good contact.  I wound up
replacing sockets in my MKIII's with milspec sockets and the problem went
away.

If a tube is gassy it can also run away in this way; I would inspect the
tubes in operation, looking for something other than normal operation.

Finally, some tube amps ran the outputs red hot; the Eico HF-89 ran 6CA7's
with the plates glowing when properly biased.  That's how they got 50 watts
output from the tube....
-- 

Mike Squires (mikes@iuax.cs.indiana.edu) Phn: 812 855 3974 (w) 812 333 6564 (h)
mikes@iuvax.cs.indiana.edu          546 N Park Ridge Rd., Bloomington, IN 47408