[Boatanchors] Re: SB-220 in AM service
Mark Shaum
k9tr at dtnspeed.net
Wed Mar 12 17:55:58 EST 2008
>The Heath SB-220 in the shack is seldom used and I would like to use it in
>AM linear mode with low power exciters such as the Heath DX-60, Knight
>T-60, HT-32 / 37, HX-500, WRL DSB-100 etc. As its rated for 1KW CW RTTY
>(10 Min max) I thought that 250W input on AM should not stress the power
>supply or tubes, in the low power position (graphite tubes) At 60%
>efficiency that should be approx. 150W rf output. Any thoughts from others
>who have used the Amp on AM ? Thanks for your input Bill KE7KK SD
My SB-220 does a fine job as an AM linear with up to 300W carrier output.
Drives with 20 to 25 watts at that level so is a valid candidate to use with
most all of the exciters you mention. Tune it up at the 1200 watt output
level (dummy load strongly suggested) then drop the drive to 20-25 watts of
carrier or whatever it takes to get 250-300 watts out without modulation.
There will be plenty of room for clean modulation peaks up to 1200W out.
The tubes glow warmingly after a long olde buzzardly AM transmission.
Mark K9TR
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