The 500V are not the 1500B screen voltage, they are the plate voltage for
the 8122 and feed the screen regulator which supplies about 300V for the
1500B screens and 225V for the 8122 screens.
But never have screen voltage on them without anode voltage, half plate
voltage is OK.
73
Peter, DJ7WW
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Paul Decker
Sent: Montag, 19. September 2022 17:17
To: amps@contesting.com
Subject: [Amps] Harris RF-110A AM-3924
Hello group.
I'm getting ready to bring a 40+ year old RF-110A online. I kept the low
voltage portion intact for the filiment, bias, and the 400 Hz chopper to the
lower. I've gutted the old 3phase power supply and replaced the 575v
screen and 2500v plate transformer with a single phase version.
My plan is to check blower function, then
Step 1. apply filiment without any 2500v plate or 500v gird.
This should keep both the 4cx1500b's and the 8122 plate and grid voltage off
and just run filiment for 24 hours or so.
Step 2. With filiment, apply 500v grid to the 4cx1500's but no plate, and
500 v plate to the 8122's let that soak for a while,
Step 3. Apply half plate voltage about 1200v to the 4cx1500's let that soak.
Step 4. Apply full plate and let soak.
Step 5. Run through the amplifier setup and alignment steps in the URT-23
manual.
I've never done a tetrode bring up, so I wonder if it is okay to have grid
without plate or vice versa, no input signal would be applied during the
burn in process.
Thoughts?
Thanks,
Paul
Kg7hf
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