Amplifier Vacuum Tubes

[Brett Gazdzinski]

I would like to point out that there are loads of good tubes around,
many places have a lot of old US tubes, I use some 100TH tubes made in the
1950's,
and also have a pile of 811a, 812a, 813,s, 4-125, 4-400,etc.
No I dont want to sell any, but there are loads of good tubes around.
Unless overloaded, most tubes seem to keep working for a long time.

I would not get any tubes from China, Russian tubes are sometimes ok,
and the ones from Eastern Europe seem good, but best is old US tubes.

Brett

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[AJSOENKE]

Having lived in Santa Barbara most of my life I have had the privilege of  
friendship with many of the staff of the original EiMac Vacuum Tube company. One
 of the last of their original Tech staff, Rad Leonard, Just passed on a few  
months ago. In the course of these acquaintances I was privy to many of the  
stories of the development of these vacuum tubes. I'm sure there are published
 accounts as well. The main thrust of these tails was the incredible
meticulous  crafting they had to go through to make these tubes right. There are
innumerable  accounts of their dealings with government contracts and the failings
of their  competitors who were attempting to copy their designs. The usual
government  contract gave the design right to the government who would then offer
those  designs to competitors for competitive bidding. The companies original
trade  secrets were not a part of the deal. The outcome was that detailed
designs were  not enough to build a successful product. The details of the exact
alloys used  for such critical components as filaments and cathodes, plates
and gridwires;  the thermal design of the feedthru pins and the correct
composition of the base  materials are all very critical.  I have never been convinced
 that these devices could be 'copied'.  Like so many devices from the  vacuum
tube era, including the rigs we used, the heart of success was the  original
design concept and philosophy - The very things that are lost when  something
is merely copied.
In the world of today, there is a belief that our technology is superior to  
that of the past and we can use that technology to create copies of things
that  are better than the original. All that and make it cheaper and in more  
volume.  It just doesn't work like that!  I have my hat off to the  guys at
Svetlana for getting as far as they have.  Some call it mojo,  others know it is
skill coupled with a philosophy and experience.  If they  keep trying and
acknowledge their failures the worldwide market will eventually  re-learn a lot that
has been lost of the past. In the mean time - some of these  old amps that
are laying around gathering dust may have some very useful spare  parts in them.
 
73 Al WA6VNN
 
 
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

In  a message dated 3/16/2008 1:23:17 P.M. Pacific Daylight Time,
[hidden email]  writes:
I have an amplifier with four 572B tubes.  I have  been
running the same Cetron 572Bs since 1976 in this
Dentron Clipperton L  and in a Hunter Bandit before.
This summer I decided to lay in another set  to stretch
the life of the amp.  I ordered a quad of the  premium
Chinese Tubes from the distributor that I considered
to be the  best available.  When I received and
installed them they didn't  work.  After some
investigation and head scratching I found that one  of
them had an open filament.

The distributor replaced them with  another set and a
rude accusation that I ruined the tubes by  overdriving
them.

The second set lasted a month, but were not as good  as
the 30 year old Cetrons when installed and were dead
by the end of the  two CQWW DX contests.  I pulled the
new tubes and reinstalled the  Cetrons which are still
going strong.

I emailed the distributor and  asked what he would
recommend that I do and how he would be willing  to
help.  After my second email, I received a very rude
phone call  from the "Customer Service Department"
which essentially told me to stuff  it.

My conclusion is that amplifier tube supply as far as
572Bs are  concerned is dead now.  The Chinese are not
making a good product and  the US distributor feels
that he can do nothing about it, so his  present
approach it to stonewall the problem.

My next amplifier will  be whatever I deem the best
solid state amp available at a price that I  can
manage.  I hope that my Clipperton will hang in until
I can  recover from paying for my K3.


Willis 'Cookie' Cooke  
K5EWJ
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