John Fielding wrote:
>
> As far as the other aspect of the argument regarding the linearity versus
> anode voltage - it is a well documented fact that the greater the anode
> supply available the more linear the operation will be for a given output
> power. Why else do we use such high voltages if we could use lower and
> safer voltages? Look again at the formula - here you can plainly see that
> the predominant factor in obtaining high output power is the voltage term!
>
This is not peculiar to tubes.
And is why the ICOM IC-781 running the PA transistors at 28 V achieves 37 dB
IMD, compared to the typical 24-28 dB from 13 V transistors (IC-565, 476, Yeasu
847, 920, etc). 50 V transistors are even better, but as long as hams use 13 V,
we will have to continue enjoying 40 kHz-wide SSB signals, as generated by a
nearby 400 W 13 volt USA-made linear on 6m.
Ian, ZS6BTE
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|