km1h at jeremy.mv.com
Sun Apr 29 16:29:42 EDT 2007
With 50-60W of drive you should see around 500W out with a single tube in
the SB220 in the CW position and tuned for 125 ma grid current. Not much
difference with 50W into two tubes.
With 2 tubes and 2 sockets you have 4 possible combinations. Be sure to use
one socket for both tubes and then switch to the other socket. It is
possible that one of the grid chokes is open.
Also be certain that your exciter is not in VSWR foldback in any of the
With 100W of drive into two GOOD tubes typical key down output is 750W on CW
and 1100W on SSB switch positions on 20M as an example. In the 50 Hz world I
wouldnt run over 900W in the SSB position without additional cooling on the
xfmr (unless it is a 50Hz version) and a high speed (or 50 Hz fan).
----- Original Message -----
From: "roller" <roller at comtech-data.se>
To: <Amps at contesting.com>
Sent: Sunday, April 29, 2007 10:40 AM
Subject: [Amps] sb220
> Hello.i am a SB220 owner.i just got it to work.clean it upp and all. after
> 4 years.but somthing is wrong i get 550 W output?... and when i try the
> 3-500z each in single use i get 550w out on a single tube ?.and when i
> install then both i still get 550w..someone?
> best regards from sweden
> Amps mailing list
> Amps at contesting.com
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