[BC] Spurious and Harmonic output of AM TX

[RichardBJohnson@comcast.net]

Doesn't anybody read what was written before they argue? As I said, 
there is no way that a frequency agile transmitter will be type 
accepted for use under part 73, so that's not a problem. A 
broadcaster, in an emergency, can deviate from any of the technical 
rules to the extent necessary to meet that emergency, as long as he 
doesn't generate "harmful interference." Because the broadcaster must 
meet the public "convenience and necessity," he is allowed to use 
special means to maintain communications. However, the broadcaster 
must receive "telegraphic authority" from the FCC (nowadays meaning 
email), for such "continued operation." This means that you can use 
your emergency transmitter, even a plate-rectified, 
grid-modulated,  self-oscillating, spark-gap ((just kidding) 
transmitter to keep on the air, then notify the FCC after. In 
broadcastings heyday (sixties) there were hundreds, perhaps 
thousands, of lash-ups used as emergency transmitters including 
government surplus BC-61!
  0 equip
ment.
--
Cheers,
Richard B. Johnson


  -------------- Original message ----------------------
From: "John Lyles" <jtml at losalamos.com>
 > Jim is correct in that to get FCC type notification, the 
transmitter must be
 > capable of meeting the suppression limits, standalone. If a tuner 
is required to
 > make a transmitter meet the FCC R&R, then it has to be included in 
the submittal
 > data for type notification and should be part of the transmitter, 
or included
 > with the system as provided to the broadcaster. Larger FM and TV 
transmitters
 > had external coaxial harmonic filters, and those were included in the data
 > taking to meet the specs.
 >
 > Dependence on the ATU to make transmission equipment meet the spurious and
 > harmonic requirements is not allowed. Also, besides conducted emissions,
 > radiated emissions must also be compliant with the rules and regs. This is
 > usually called the 'cabinet radiation' measurement and it is a 
real concern as
 > harmonic currents can cause significant leakage across the joints 
and seams of
 > the cabinet, if they are not RF tight.
 >
 > John