[BC] Re: 317 and MW-50

[Gary Blau]

Xmitters at aol.com wrote:
 
> To be totally correct, the envelope, and not the carrier pinches off at the
> negative modulation trough. Vector sum of the carrier and the two sidebands is
> zero at that instant.

Of course.  

> IMD was an issue with our 317C-3 as well. We usually had to swap PA tubes
> around and tune up again to see which tube worked the best in which position. A
> good friend of mine can hear the difference between the 317 and MW50 with the
> 317 sounding "warmer". I often wondered what the PA screen audio coupling
> transformer did to performance regarding overshoots and distortion from the iron in
> general. There was a nice audio feedback loop that worked very well that
> probably killed most of it, but I often wondered what exactly that transformer was
> doing to the audio and the effect on loudness. At the time I was in Chicago,
> of the 50 kW stations almost everyone was using the 317 so engineering got
> little pressure from programming about loudness. I think WJJD had their DX-50
> sometime in the mid 90's when I was in that market. anyone remember?

IMD was never an issue with our 317, I was referring to the MW50.  The
317's numbers were always a little lower than the 50.  In particular,
the MW50 was much harder to get consistent numbers out of across the
spectrum than the 317, especially as you got to mod levels above 80% at
freqs above 5khz where envelope closure (which we used to just
conveniently call 'carrier closure', as misleading as that may be) was
elusive.

I never saw much ringing or tilt out of the 317's screen mod xfmr.  It
did really well, considering.

But we could always tell the difference between the two rigs on the air
as well.
Our MW was always a reliable backup, contrary to horror stories other
owners have told me.  Maybe we got the good one.   

g