The highest output I've EVER seen from an SB-200 is 650 watts.
Mark WB8JKR
On Sat, 06 Dec 2003 14:37:46 -0800 Mike Selfridge <scifiguy@starband.net>
writes:
> I have a very well kept Heathkit SB-200 I purchased a couple months
> ago. It has the Harbach power supply, soft start, and soft key
> mods. I am
> running it on 240VAC (measures 232VAC when keydown). The tubes are
> new
> (about 20 hours) Taylor 572Bs.
>
> Before buying the amp, I had read that the SB-200 can output about
> 500W to
> 700W CW, with 100W input. However, much to my surprise and delight,
> this
> amp puts out a lot more.
>
> The highest output seems to be on 20 meters, where it actually
> achieves
> 1100W CW into a dummy load (found this out by accident, when I drove
> it
> with 100W, then noticed the plate current was way too high, so very
> quickly
> reduced the drive). At 70W input, the plate current reads 500mA,
> and the
> output is about 900W CW. 40 and 80 meters also produce similar
> power, but
> with full 100W drive.
>
> Now, before I hear that my power meter must be bad or out of
> calibration,
> let me say that the meter is new, and reads the same as my backup
> meter, as
> well as reading exactly what it should with my FT-897 (reads the
> same as
> the test data on the calibration sheet from Yaesu, within a couple
> percent).
>
> I checked the output on all bands, using a spectrum analyzer, and
> found
> nothing unusual, so I know it is not producing parasitic
> oscillations, nor
> is the harmonic content too high. On the air, I have had nothing
> but
> positive reports.
>
> I know you can't get something for nothing, and class B amplifiers
> don't
> operate at 93% efficiency (yup, that's what I calculated), so I
> assume the
> meter on the front of the amplifier must be inaccurate. I suspect
> the
> plate current and/or high voltage is higher than the meter shows, so
> I'll
> have to calibrate it with a current source, and replace the
> appropriate
> components to give an accurate reading.
>
> Has anyone else with an SB-200 seen output this high? My web
> searches show
> that most get about 600W CW. I don't push the output to the limit
> on CW
> operation, but I love the ability to get 1100W PEP on SSB!
>
> 73
>
> --Mike (N6QG)
>
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