-----Original Message-----
From: amps-admin@contesting.com [mailto:amps-admin@contesting.com]On
Behalf Of Glenn McNeil
Sent: 14 June 2002 07:33
To: amps@contesting.com
Subject: [Amps] 4CX800/GU74B Socket
Hi Guys...
I'm about to start construction for a 2 meter linear using a GU74B (
4CX800 ). The socket I have is a military one, with built in chimney and an
external screen ring. This ring makes contact with the screen area of the
valve.
At present it has 4 x 1000pf 1kv disc ceramic caps between the screen
"ring" and ground.
My question....
(a) Is this socket useable at 2 meters
(b) I note that about 1100pf is usually the screen capacitance in eimac
sockets for the 4CX250...can I just solder an even number of disc ceramics
to the socket to total about 1100pf, or am I missing something ??
If the socket is useable at 2 meters, it seems a great way to construct a
screen capacitor, as it's repairable. The socket is made out of a brown
bakelite material and has the following written by hand on it :
U 84812006
Regards,
Glenn
VK4TZL
Glenn I agree with Art , run in grounded screen, that way you ensure a low
impedance screen connection. It is quite easy to implement and you don't
have to repair the screen bypass cap when there is the occasional flashover.
I ran a 4cx1500 on 2m eme for about 4 years like this. G3SEK's tetrode
boards can accommodate this power supply scheme and work particularly well
with the GU74B.
Regards
Conrad Farlow G0RUZ
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