[BC] Re: SUPER MODULATION & AM STANDARDS

[DHultsman5@aol.com]

In a message dated 5/12/05 12:05:28 A.M. Central Daylight Time,  
broadcast-request at radiolists.net writes:

Were  there actually any confirmed and documented cases
of harmful interference  that resulted from stations
modulating above 125% positive?  In other  words, was a
new FCC rule really needed to protect  innocent
bystanders?  Or was this, in fact, only a response to
some  politically-connected 50 kW operators crying foul
because the "hot-rodded"  5 kW guys were beating them
in loudness?




*********************
 
Mark
 
I was around in those days before the FCC limits.  Most transmitter  would 
not do much positive modulation especially 50 kW. transmitters.
 
I can't recall the actual FCC proceedings.  But I do recall that CCA  souped 
up their 1 kW AM to do 150% and that Gates did the BC-5H-1A with the  external 
modulator/power supply in a separate external box claiming greater than  125% 
positive.
 
It would be likely that the  big 50's of the day may have been the  
instigators of the FCC Ruling.  I know the 5 kW. rockers around the country  really did 
some loudness battles in the 1960's when we started getting new  limiters and 
fast AGC's. 
 
I agree maybe this should be looked at again.  Same with opening up  the 
rules for reduced carrier and Kahn's  CSSB  pushing the modulation  into one 
sideband, upper or lower  away from your closest adjacent  channel.  With 
deregulation the basic requirements should be on frequency,  best performance, staying 
within the spectral mask.
 
Leonard Kahn filed requests for proposed rule making for CSSB on AM  twice.  
The majority of stations were against it as I recall mainly because  it would 
open up additional AM channels in many markets.  The compatible  
single-sideband was used in international broadcasting to reduce bandwidth and  still had 
enough carrier for proper detection and keeping noise down.
 
Any additional comments from any of you older AM guys??????????
 
Dave Hultsman