[Amps] SB-220 WARC bands

[Tom Rauch]

> Power out on 12 and 17m is around 400W and 30m doesn't really work at
> all. The reason for the low output, compared to all of you who
> answered (most of you have over 1KW out), I don't know. Are the tubes
> tired or do I have too little driving power. The IC-765 only delivers
> 90-100W and that, I know, is not enough to drive 2x3-500Z to full
> output. The output from the amp is anywhere from 600-900W depending on
> band, 10-80M.

The factory designed rating for the SB-220 is 1kW INPUT (~600w 
output) on CW and RTTY, and 2KW PEP on SSB (~1200 watts 
PEP out) on SSB.

Good meters, like the Bird 43, have +-5% of full scale anywhere on 
the scale tolerance if they are within factory specs. Other meters 
are generally worse for tolerance. So a 2500w slug in a properly 
calibrated Bird 43 at 1000 watts true power could read between 875 
and 1175 watts. People often pretend Bird meters are 0% 
tolerance, but that is dreaming. I have a stack of calibration curves 
for slugs and meters I have to use, and that is with meters and 
slugs that are factory calibrated from time to time. 

You are really not that far off, and actually may be right on if your 
meter is reading on the low side. Measurements are always less 
than perfect, and RF power is one of the worse areas to measure.
73, Tom W8JI
W8JI@contesting.com