[ARC5] Harmonic question

[Glen Zook]

There were a number of "Novice Class" CW transmitters that doubled in the final amplifier for the 10-meter band (i.e. Heath DX-20 and WRL Globe Chief 90 / 90A / Deluxe) that were modulated after the operator upgraded to Conditional / General Class.  WRL even had both a screen modulator and a plate modulator that were designed to be used with the Globe Chief series.


The resulting modulation quality wasn't really much, if any, different from that on the lower frequency bands.

 Glen, K9STH 
Website: http://k9sth.net

      From: "Fuqua, Bill L" <wlfuqu00 at uky.edu>
 To: AKLDGUY . <neilb0627 at gmail.com>; ARC-5 List <arc5 at mailman.qth.net> 
 Sent: Saturday, April 15, 2017 9:34 PM
 Subject: Re: [ARC5] Harmonic question
   
#yiv5050956103 #yiv5050956103 -- P {margin-top:0;margin-bottom:0;}#yiv5050956103 
  It depends on the source of the harmonics.If the harmonics are generated by the final amplifier of a plate modulated AM transmitter then it should sound as normal with a small exception. If the RF on the  final amplifier's plate has the same waveform thru out the audio cycle then the harmonics will be equally modulated and the signals received at harmonic related frequencies will sound normal.   However, the amplifier plate may not exhibit the same wave form as the plate voltage is changed, in that case there will be some audio distortion.   If the harmonics are produced by something after the modulation process, such as diode in a RF power meter, then the Carrier and sidebands will be multiplied by the harmonic number thus producing higher order sidebands on along with the normal ones. Lots of distortion. 
  There have been cheap 6 and 2 meter AM transmitters where the final is an amplitude modulated doubler.Look at the Harvey Wells Bandmaster. On 2 meters the final functions as a doubler.
   
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