Robert,
What is the idling current with no drive (ZSAC)? Do you have a method to
vary the bias? I assume that you have some protection circuit active. Do
you know which one is tripping? Grid or Anode? Does the grid meter jump
up when the failure occurs?
73, Tony W4ZT
Original Message
-----------------------------------------
To: amps@contesting.com
Subject: [Amps] GS35 144MHz amp faileur, how should we test it.....?
From: Robert Thain <g0hgw@yahoo.com>
Reply-to: Robert Thain <g0hgw@yahoo.com>
Date: Wed, 5 Jul 2006 05:40:27 -0700 (PDT)
List-post: <mailto:amps@contesting.com>
Hello,
I am contacting you on behalf of our radio club.
Last weekend we had a failure of our 144MHz GS35 amp.
This amp is relatively new (about 100Hrs of use) and the tube was new.
The amp
and tube was commissioned properly.
How should we test the tube to see if its OK ?
The symptoms were , Once the HT had increased to about 3KV there would be a
loud clanging from inside the amp, then the HT would drop, probably the
protection kicking in. Some time there would be delay of a few minuets
before
it would 'clang and cut'. However every time we tried to transmit it would
systematically 'clang and cut'. The clanging was very loud and sounded
mechanical, like hitting the side of a thick metal box.
We opened the amp, there were no physical signs of damage, IE no burn
marks or
signs of arcing.
We will have an autopsy party on Friday evening.
We will start by checking the GS35 , and then see if the Power supply /
HT is
working correctly (with no load).
If you can point us in the right direction please send me a mail.
G0HGW(at)yahoo.com (at) = @ (This is to try and reduce any spam.)
thanks Robert
PS I am still looking for some valve bases for 3CX100 / 2C39.
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|