[ICOM] ICOM's on AM

[Adam Farson]

Hi Ed,

I have checked all my IC-756Pro radios (Pro, Pro2 and now Pro3) on an HP
spectrum analyser with digital storage, and have never seen an RF power
spike on keying. Checking the Pro3 now with the Quadra in AM mode, with 250W
resting-carrier output, I do not see any overshoot at all on the
peak-reading power scale. I checked further with an oscilloscope looking at
the RF envelope on the antenna feedline, and did not see any overshoot there
either.
  
When operating AM with the PW-1 or Quadra, the drive level must be set for
no more than 250W resting carrier. When barefoot, the maximum is 25W resting
carrier.
 
http://www.ab4oj.com/icom/pro_notes.html#AM

The IC-781 has a 250W power spike on keying in SSB mode, due to ALC
overshoot This is a known issue, and there is an excellent fix for it. 

http://www.ab4oj.com/icom/ic781/docs/ic781alc_k1vf.pdf

(My AM career ended in 1963, when I learned about "Kilowatts from Heaven" -
the 9 dB advantage of SSB over AM - as an EE student.)

Cheers for now, 73,
Adam VA7OJ/AB4OJ



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