[AMRadio] Re: How can we rid the HF bands of AM ?


Jim Wilhite w5jo at brightok.net
Sun Aug 7 17:52:48 EDT 2005


My point exactly Geoff:  PEP is a calculation for most hams who don't have a 
scope (most don't).  Input is a different story.  RMS reading can be taken 
off meters with a single tone signal and using the plate voltage times the 
current gives you a 10% (depending on the meters and shunt) accuracy.

This, however, is not true of PEP, as you have so aptly pointed out.  Even 
today's PEP wattmeters are not that accurate (better than in the past, but 
not good enough).

After all who really understands that when calculating the RF safety 
margins, use of 33 1/3% duty cycle for SSB  is appropriate?

73  Jim
W5JO


>
> Amen.  Hey, I'm all for running a full kW DC input again, and more power 
> to those of y'all that can pull it off.  I'm plagued with a bad rash of 
> neighboritis.
>
> But, still.. for accuracy of measurment, how hard is it to calculate 500w 
> DC input?  (uh, gee.. 2500v x 200mA =... Cornbread?)   ;-)
>
> Besides, Jim - given that Class C finals are 75% efficient (on average), 
> what's 75% of 500w?
>
> (just to point you in the right direction, 500w DC input is -half- of what 
> we -could- run, given that 1500w PEP is 'generically considered' to be 
> 100% modulation of the product of 75% of a 500w carrier.)





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