[AMPS] Purpose of CW/SSB switch

[Matt--K7BG]

At 09:59 AM 9-11-98 -0600, Richard W. Ehrhorn wrote:
>
>Hello Phil,
>
>ALPHA amps built before the FCC power limit was changed (about 1977-78) 
>were designed for convenient "1 kW dc INPUT". That old rule, in effect 
>since the CW & AM 30's, was ambiguous and about 90% misunderstood when 
>applied to SSB. But it translated roughly into something like 2.5+/- kW PEP 
>dc plate INPUT, taking SSB duty cycle into account.
>
>So the amps' HI or SSB position provides plate voltage appropriate for good 
>linearity and efficiency at ~2.5 kW PEP dc input, which corresponds to 
>about 1.5 kW PEP RF OUTPUT, which the post-1977 rules specify.
>
>The LO or CW position delivers a lower dc plate voltage which is optimized 
>for 1.0 kW dc input on CW (as the old rules allowed). Also, the design is 
>such that when the older amp is tuned properly for CW in the LO position, 
>just switching to HI (SSB) sets it up for efficient SSB at 2+ kW PEP 
>without any further tune/load adjustments [i.e., both conditions require 
>approximately the same plate load resistance for the tube(s)].

Dick, So does this mean that one SHOULD NOT run older amps in the SSB/HI
position while operating CW mode? I'm still a bit unclear on this after
following this thread. I have been doing just that. OOPS?

73, Matt--K7BG


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