[AMPS] SB-220 input circuit

[Pete Smith]

At 07:35 PM 8/2/99 -0400, Tom wrote:
>Hi Pete,
>
>> >From time to time we've seen posts about how the SB-220's input network
>> >is
>> badly designed for 10 meters, and that results in lower output.
>
>Part of the problem is lead lengths and component tolerances, as 
>well as wiring dress.
>
>There is no solution other than dropping the panel and working on 
>the input.
> 
>> Mine has a relatively high input SWR (ca. 1.8:1 on the part of 10 meters
>> I'm interested in) and suffers from low 10m. output (ca. 800 watts at
>> best), but even when I use the built-in tuner on my transceiver to match
>> the input perfectly, the output doesn't rise significantly.  Why is this?
>
>Does your rig normally shut down at that SWR? That would be the 
>only ill effect.

No, not at all.  What I *do* see is below-normal grid and plate current
compared to the lower bands, and commensurately less output.  It's been
opined that the problem is not the match to the transceiver, but rather the
match from the input network to the tubes.  What say you?

73, Pete Smith N4ZR
n4zr@contesting.com 

Sometimes a tower is just a tower

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