[Drake] T4XB tubes

[Al Parker]

Hi Ed,
    It's not a good idea to wholesale change tubes.  Then you'll not know
where the  problem was, if in fact it was a tube (I kinda doubt that it
is), and you'll end up with a used set of tubes, 90% of which are
perfectly good, but you won't know which.  A full scale replacement will
probably require a fullscale alignment, tho' maybe that wouldn't hurt.
Tubes rarely fail in a jump like you've seen, unless it's a jump to
zero/complete failure.  Resistors can often, after age/heat, etc, either
open up, or change fairly abruptly to a higher value.
    In your case I'd take a look at several resistors that often cause a
problem like yours.
1.  the final screen and cathode resistors,
2.  the one feeding the plate of the driver, it in particular can be your
problem, the others just add to it.
    Save yourself some $, time, downtime, etc.
    It is nice to have some spare tubes on hand, but few of us (I suspect)
carry a full set.
FWIW
73,
Al, W8UT
New Bern, NC
BoatAnchors appreciated here
http://www.thecompendium.net/radio/
http://www.hammarlund.info

----- Original Message ----- 
From: "ed brooks" <ed.brooks at att.net>
To: <drake at mailman.qth.net>
Sent: Thursday, December 30, 2004 4:41 PM
Subject: [Drake] T4XB tubes

>
> But figured I'd replace all the tubes at one whack rather than one now
> and one later.
>
> Ed, W5HTW