Looking at waveforms of the detector stage

1/23/2011 7:14:49 PMDaniel M.

Dear people,
Have a question about viewing waveforms from a scope at the RF input to the detector and the audio signal at rhe output of the detector. Can this be done and if so how would the scope be connected to view these waveforms? I would like to see what these waveforms look like!!! Thank you all kindly for any input!!!!
Daniel M.

1/25/2011 12:20:36 AMPeter G Balazsy

Hope this helps:

1/25/2011 12:08:57 PMDaniel M.

:Hope this helps:
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Thank you, this is a big help!!!
Daniel M.

1/25/2011 7:34:26 PMDoug Criner

Let us know the results of your experiment.

I suspect the audio signal will look like an explosion in a noodle factory - unless you inject a pure audio tone or have a memory 'scope. Likewise, the modulated IF input to the detector.

1/26/2011 1:27:53 PMRene

:Let us know the results of your experiment.
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:I suspect the audio signal will look like an explosion in a noodle factory - unless you inject a pure audio tone or have a memory 'scope. Likewise, the modulated IF input to the detector.
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The audio does look interesting. The modulated IF should simply look like a 455 kHz (or whatever the IF frequency is) sine wave, depending on what time/frequency base your scope is set at.

1/26/2011 6:46:12 PMEdd

Sir Daniel Mmmmm. . . . .

Using relevant photos and not having to pull out my scope and photo-document again.

The first photos are with the hoz sweep rate quite slow to fully show the demodulated audio as the bottom channel trace and with the IF RF at the top.

The other is with the time base towards its fastest rate and therefore the stretching out of the 455 such as it showing up as multiple 455 wavelets at the top and with the heavier amplified undulating audio as being the bottom trace.

Test points for IF RF are at the diode plate of the radio . . . or the preceding IF plate circuitry while the detected audio is at the bottom of the secondary 2nd IF transformer.

The last pic set is of the scope is showing a Sine modulated tone onto a RF carrier from a signal generator.

With the sine at the top and the ,yet unmodulated, RF waveform being shown at the bottom.

73's de Edd

::Let us know the results of your experiment.
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::I suspect the audio signal will look like an explosion in a noodle factory - unless you inject a pure audio tone or have a memory 'scope. Likewise, the modulated IF input to the detector.

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:The audio does look interesting. The modulated IF should simply look like a 455 kHz (or whatever the IF frequency is) sine wave, depending on what time/frequency base your scope is set at.
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1/26/2011 11:02:46 PMDaniel M.

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:Sir Daniel Mmmmm. . . . .
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:Using relevant photos and not having to pull out my scope and photo-document again.
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:The first photos are with the hoz sweep rate quite slow to fully show the demodulated audio as the bottom channel trace and with the IF RF at the top.
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:The other is with the time base towards its fastest rate and therefore the stretching out of the 455 such as it showing up as multiple 455 wavelets at the top and with the heavier amplified undulating audio as being the bottom trace.
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:Test points for IF RF are at the diode plate of the radio . . . or the preceding IF plate circuitry while the detected audio is at the bottom of the secondary 2nd IF transformer.
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:The last pic set is of the scope is showing a Sine modulated tone onto a RF carrier from a signal generator.
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:With the sine at the top and the ,yet unmodulated, RF waveform being shown at the bottom.
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:73's de Edd
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:::Let us know the results of your experiment.
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:::I suspect the audio signal will look like an explosion in a noodle factory - unless you inject a pure audio tone or have a memory 'scope. Likewise, the modulated IF input to the detector.
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::The audio does look interesting. The modulated IF should simply look like a 455 kHz (or whatever the IF frequency is) sine wave, depending on what time/frequency base your scope is set at.
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Thanks people for your input on my question. I will let you know what I find. I am just so interested in the electronics in these vintage radios. Together, we will keep the tubes glowing!!!!!!!
Daniel M.