[Central-Electronics] Re: Using 100V with 600L

Sun, 25 Jan 2004 22:49:05 -0600

Nothing like answering your own question is there?

But for the benefit of a couple of you who have asked, I guess I had the
600L biasing figured out right.  I went ahead and wired the N.O. contacts of
the 100V relay output to terminals 1 and 2 of the 600L and left jumper 3-4
intact.   With the 600L HV on and in receive mode, the meter shows no output
and no tube noise is heard.   When the 600L is keyed the bias is reduced and
the 600L idles at 70 watts as per the manual adjustment.

I hadn't used the amp in about 5 years but after blowing the fuse (forgot MV
rectifiers need time to warm up!) everything came up fine and I got good
output on 20 meters and a nice report from the Vintage Sideband net.    With
the Johnson electronic T/R switch it is very quiet and smooth.    Central
Electronics engineers built a lot of flexibility into the t/r and bias
circuits so that with just a bit more work you can wire the amplifer for
full break-in CW operation.   I have mine running with a 75A4 receiver but
I'm going to stop calling it the "poor mans KWS-1".   With the built-in
o'scope, broadband tuning, and smooth QRO operation I think the 100V/600L
combo is better!

73, Bob W9RAN

----- Original Message ----- 
From: "Robert Nickels" <[email protected]>
To: <[email protected]>
Sent: Saturday, January 24, 2004 11:15 AM
Subject: Using 100V with 600L

> Thought I'd wake up this list with a question...
>
> I'd like to run my 100V with my 600L amplifier, using an electronic T/R
> switch on the output of the linear to feed the receiver.   My question is
> about how to wire up the bias to prevent tube noise and excess plate
> dissipation during receive.   The 600L has a built-in 100 volt bias supply
> and can also accept external bias from an exciter.   According to the 600L
> manual to use the built-in bias method,  I should to wire the N.O.
external
> relay contacts from the 100V to terminals 1 and 2 on the 600L which in a
> roundabout way on the schematic looks like it will turn on the 75 volt
> regulator tube when the exciter is in transmit.  In receive, the VR tube
> will be floating, allowing the bias to rise to a much higher value,
cutting
> off the 813.  (The manual doesn't say so, but this assumes the jumper
> between terminals 3 and 4 is in place to ground the plus side of the bias
> supply.)
>
> Can anyone confirm that I've got this right?
>
> Thanks and 73,
> Bob W9RAN
>