Thats fairly normal and coupled with generally low output on all bands.
Output goes up a bit on a 240V line and/or with full output tubes.
The 80M issue is due to the 50uh plate choke and to the undersized filament
choke.
Carl
KM1H
----- Original Message -----
From: "Ian Hill - K8MM" <ihk8mm@charter.net>
To: <amps@contesting.com>
Sent: Saturday, September 12, 2009 5:56 PM
Subject: [Amps] SB-200 Low output power on 80M - edited to fit screen
>I have an SB-200 that putting out less than expect power on 80M. Tuning
> was done in accordance to Heathkit's instructions....basically for
> maximum smoke and reduce the drive a bit if the grid current goes over
> 100mA. I expected the RF output power to be equal to or great than the
> power output on 40M and 20M, and then start falling off as you go higher
> in frequency. This has been my experience with other amplifiers with a
> pair of 572B tubes.
>
> The tuned input SWR on 80M is 1.2 - 1.
> Drive = 100W
> Any thoughts what is going on?
>
> Band Plate V. Plate Cur. Grid Cur. Output power
>
> 80 1950 .460 .064 500
>
> 40 1950 .400 .094 675
>
> 20 1950 .400 .100 650
>
> 15 1950 .380 .100 550
>
> 10 1950 .460 .100 450
>
>
> Thanks,
> Ian - K8MM
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