Amplifier Vacuum Tubes

[WILLIS COOKE]

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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[Bill W4ZV]

If I were looking for a 1.5 kW tube amp today, I would look for one using either two 3CX800A7 (peak-rated 3CPX800A7) or one 8877 (peak-rated 3CPX1500A7).  Reasonably priced Eimac pulls from periodic maintenance of MRI equipment in many hospitals ensures they should be around for quite awhile.  Pulls are available from many sources including hams like WA8WZG and another guy whose call escapes me at the moment.

http://www.wa8wzg.net/forsale.htm

I would personally avoid Chinese glass tubes for quality reasons and Russian ceramic tubes (i.e. GU74B/4CX800) which are becoming scarce and expensive.

And hopefully Elecraft will resume their solid-state amp project once the K3 settles down!

73,  Bill

[WILLIS COOKE]

--- Paul Meier <[hidden email]> wrote:

> I would broadcast to everyone the name of the
> company that has no customer
> service so others won't deal with them and get hurt.
>
> Paul K7PM
>
>
I thought that I had done just that, but it went out
as a private communication to one member.  The company
was RF Parts who I thought to be the premier supplier
of all such tubes and parts.  I hesitated to mention
their name because I thought that they might be a
victim of poor Chinese quality control as we all are
when we are stuck with buying their products.  But I
received another story which parallels mine that
happened nine years ago.  I really wanted RF Parts to
redeem themselves, not so much for the $180 that I am
out for the tubes, but so that the ham community could
have a good reliable supplier for our amplifier parts.
 

Willis 'Cookie' Cooke
K5EWJ
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