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 Post subject: Re: EICO signal generator output clean up
PostPosted: Jan Sat 18, 2020 12:39 am 
Member

Joined: Sep Thu 23, 2010 6:37 am
Posts: 12010
Location: Powell River BC Canada
The concept of AM vanishes at the end of the transmitter voltage exiting
the feed cable and entering the transmitter aerial.

Beyond the practical near field it vanishes into the universe of noise.

Tesla never found the lossless conduit to everywhere.

The signal generator is a good start if metalically connected to
the radio.

When you are listening to a radio at night, and you hear lightning
crashes in the background, the RF and IF amplifiers are de tuned ,
however sightly, by extra energy that distorts the resonance of the
coils. This is equivalent to extra plate resistance.

Digital radios are fine, as long as you are happy with approximation
of the modulated signal.

_________________
de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: EICO signal generator output clean up
PostPosted: Jan Sat 18, 2020 1:26 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 23561
Location: Somers, CT
bob91343 wrote:


On a spectrum analyzer I see AM as three signals, the carrier and two side frequencies. But on FM even the smallest deviation results in many side frequencies. The energy for the side frequencies on AM comes from the modulator. In FM it's 'stolen' from the carrier, so at certain modulation levels the carrier actually disappears.


Bessel nulls.

SG-8 FMing was evident when tuning off carrier on an AM receiver. You can hear the FM slope detection artifacts if
not tuned to center carrier.

Pete

_________________
Just because it can be done doesn't mean it should be done.


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 Post subject: Re: EICO signal generator output clean up
PostPosted: Jan Mon 27, 2020 5:36 am 
Member

Joined: Dec Sat 28, 2019 4:18 pm
Posts: 85
Rich, W3HWJ wrote:
Same experience; same result! I even tried to put a short skirt on the pig (added a Zener to regulate the B+). Still a pig.
Rich

Voltage regulation will improve frequency stability. It will do little to improve waveform shape.

John


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 Post subject: Re: EICO signal generator output clean up
PostPosted: Jan Mon 27, 2020 5:50 am 
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Joined: Jan Tue 10, 2012 8:39 am
Posts: 988
The modern buzzword for unwanted FM is phase noise. Basically it's an unsteady carrier frequency. It covers everything from drift to hum and upwards to signal leakage and so on.


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