[Milsurplus] [ARC5] Harmonic question

[Sheldon Daitch]

Neil,


Sure, as all transmitters develop some level of harmonic emissions.

Most modern commercial transmitters have near negligible harmonic emissions, but near negligible doesn't mean they don't exist.

As to audio quality, here is what I just found on a quick and dirty test for the second harmonic of 690 kHz, WOKV (the old WAPE).

Why this one?

Their day-time transmitter site is about 1228 smoots or 6860 feet from my house and the second harmonic very  easy to receive.   Audio quality, not so great, although it was perfectly understandable, with maybe 10% distortion.  What was interesting was the amount of "buzz" associated with the second harmonic, no doubt a product of the digital type transmitter.  I also noted nothing heard 10 kHz on either side of the second harmonic, the resolution of a digital tuned automotive receiver.

On the specifics of the third harmonic, RCA utilized the third harmonic energy of a tube amplifier to increase the plate efficiency in the 5kW BTA-5T.

One technical document on this transmitter is at:

http://www.nrcdxas.org/articles/bta5t/


73


Sheldon

WA4MZZ




________________________________
From: ARC5 <arc5-bounces at mailman.qth.net> on behalf of AKLDGUY . <neilb0627 at gmail.com>
Sent: Sunday, April 16, 2017 4:52 AM
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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