>
>Last week, I asked for advice in the operation of my newly purchased and
>repaired SB-220. Here is a summary of the responses that I received.
>Thanks to all those that sent me email directly.
>
>1. Lower power on 10 meters is typical. Higher SWR on input to the amp is
>a major contributor to this problem. Several articles have discussed
>modifications to fix the SWR.
>
>2. Operation in the "SSB" / high voltage switch setting. General consensus
>was that this high/low voltage switch was used to meet the 1970'sFCC power
>input limits.
The Heath transformer approx. has a 600w core.
> Today's power output limits have eliminated the need to
>switch between high and low switch settings.
Under the old fcc power limits, by using a tuning pulser, one could
legally tune up a SB220 at c. 2400w pep input/1500w pep out. .
>Everyone that responded said
>they routinely operate CW and SSB on the higher SSB switch setting.
>Several cautioned against operating in the SSB setting for very high duty
>cycles -- might tend to stress the power supply too much.
pretty good advise, Nat. If you ever need to replace the hv trans.,
Peter W. Dahl can build a tapped secondary (more efficient) hv
transformer that will deliver more suds. . .
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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