The eBay Russian tubes, even when shipped from the USA yield poor results.
A buddy of mine thought hey, let's pick up a cheap spare set of 4CX800
Russian tubes as a back up for the ones in his QRO. He plugged them in and
turned the amp on.
The amp went BOOM... The smoke was Grayish-White. Took out not just the
fuses in the screen supply and mains, but did some other power supply damage
too.
He talked to Mr Russian Supplier (hopefully not a guy on here) and he
responded you need to burn in and degass the tubes before running up the
other voltages on them. The guy would send another set on return of the
first set.
Well, he got a second set, the AMP WENT BOOM once again, parts blew up and
once again filled the shack with acrid smoke of the same color. FOOL me
once - Fool me twice and he got smart and didn't try it a third time.
Since there is NO RETURN, he ate the tubes. Russian Beryllium Oxide is
tastier than USA stuff, it was probably the added Cherry Flavoring.
Turns out these are NOS military units from dubious sources. They've
possibly been laying in a coffee can in some underground replacement parts
depot in Ural since 1987.
If a guy was to build up a test jig, apply filaments, have controlled
screen, grid and plate supplies with protection you could possibly sort
through these tubes and make good of these supplies. Possibly even resell.
This is what Mr Supplier should be doing. Instead he's creating a demand
for amplifier replacement parts.
I'd steer clear of these military surplus supplies of non-USA tubes.
NOW if you find somebody who's selling surplus SS-22 with mobile launchers
I'm interested no matter what the condition. HAVE PAYPAL ready to bid.
BOB DD
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
Behalf Of Larry
Sent: Thursday, September 28, 2006 1:44 PM
To: AMPS
Subject: [Amps] Bad tubes from Ebay
Recent purchases of russian tubes from Ebay sellers have been pretty
disappointing with more than 50% DOA's. A summary of my experience is at:
http://w7iuv.com/badtubes.html
And yes, I did try to "condition" them first but it's hard to fix
mechanical shorts!
As for me, I will no longer buy tubes from non-US sources.
73, Larry
--
Larry - W7IUV
DN07dg
http://w7iuv.com
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