[ARC5] Harmonic question

[Fuqua, Bill L]

  I was not where you were going with this question.

But if you are trying to track now the source of harmonics knowing that the final itself would not introduce noticeable audible distortion no the harmonics but some other device would.


73

Bill wa4lav


________________________________
From: AKLDGUY . <neilb0627 at gmail.com>
Sent: Saturday, April 15, 2017 11:06 PM
To: Fuqua, Bill L; ARC-5 List
Subject: Re: [ARC5] Harmonic question

> 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.

Seems a reasonable explanation.

 > If the harmonics are produced by something after the modulation process, such as diode in a RF power meter,...

No, the question asked was not about frequency multiplying, only the normal harmonics unavoidably produced
in a MOPA transmitter.

73 de Neil ZL1ANM


On Sun, Apr 16, 2017 at 2:33 PM, Fuqua, Bill L <wlfuqu00 at uky.edu<mailto:wlfuqu00 at uky.edu>> wrote:


  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.

73

Bill wa4lav


________________________________
From: ARC5 <arc5-bounces at mailman.qth.net<mailto:arc5-bounces at mailman.qth.net>> on behalf of AKLDGUY . <neilb0627 at gmail.com<mailto:neilb0627 at gmail.com>>
Sent: Saturday, April 15, 2017 9:52 PM
To: ARC-5 List; milsurplus
Subject: [ARC5] Harmonic question

Suppose I have a properly adjusted AM transmitter and am operating it.

What would a nearby listener hear at say, the third or fifth harmonic,
assuming a good strength carrier at that frequency is present at his
receiver?

Is the bandwidth of the sidebands 3x or 5x, so all that's heard is
incomprehensible splatter?

This is not a trick question. The textbooks don't address this at all.

73 de Neil ZL1ANM


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