In a message dated 11/22/04 7:56:07 PM, [EMAIL PROTECTED] writes:
> One thinks of MANY sweep tubes rated for so-called Pdiss of 16 > watts and 20 watts that are regularly run at hundreds of watts of > RF! The tubes don't seem to melt. > > I think of the ubiquitous 6JS6C with a rating of 30 watts. > Yaesu ran a pair of these at 260 watts input in their FT101 series. > Many guys ran them at 260 watts p.e.p. on SSB and 260 watts CW. > Assuming 65% efficiency, you have 35% of 260 watts going into > the plates. That is to say 91 watts split between the two tubes. > UH oh - POP! But no, they didn't. > Yaesu's instructions were "don't hold key down for more than 10 sec on tune up!" Otherwise - POP! Voice is a low duty cycle signal. In SSB service the average dissipation level can be kept within reasonable limits unless heavy voice processing is involved. > > Then when you throttle that FT-101 back to 40 watts input on AM > and go to your 30% efficiency (if it is) then you are actually > putting only 20 watts carrier per tube which is SAFER. > > Is that correct? > > Actually, on AM the FT-101 is throttled back to something like 100 W INPUT, 25 - 30 W carrier OUTPUT. Optional fan recommended. > How about some of the othre rigs that rated their 2 sweep tube > finals for 560 Watts or even 800 watts!? > Yes, the SWAN 750 for example. Had one in our Club back East. Be light on the key with this sucker or definitely POP! Dennis D. W7QHO Glendale, CA
