[Amps] IMD & ALC's

[Radio WC6W]

On Sat, 3 Jan 2004 00:20:14 -0800 R.Measures <r at somis.org> writes:
 
Hi Craig & Rich,

> >I have not read or seen data on the ALC overshoot  problems. The 
> ARRL reviews seem to politely ignore  the issue. 
> 
> **  I see c. 20% overshoot on my TS-440S on the first syllable.  
> Running almost no ALC helps.  

   Same radio here; same problem.

  NEVER running into "factory" ALC helps more.  :-)

> >My main interest in this area is
> >too emit the cleanest possible signal. Its becoming a uphill battle to
find
> >a new model radio with a clean transmitter without ALC,  key clicks
and bad
> >IMD problems.
> 
> **  Without some form of ALC, excess IMD is a virtual guarantee --  

  Not necessarily.   Just use some form of hard limiting before the
"box".    I run a RF clipper with 20 dB of headroom.   

  A great (fast) audio limiter (i.e. an ancient Spectrasonics 610) is
also a possibility.

  With the mike level under control, one can set the power level just
like a real radio station and never experience any ALC action;  nor
clipping.

73 & Happy New Year,
   Marv  WC6W









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