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Hints, Tips and Solutions (Do NOT post requests for help here) If you have any useful general hints and tips for vintage technology repair and restoration, please share them here. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

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Old 9th Jan 2009, 2:26 am   #1
Top Cap
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Default YAESU VR500 as signal generator

This trick will probably work with other scanning receivers if you can find out the intermediate frequencies used within. In the case of the Yaesu VR500, the I.F. is 465 kHz and the local oscillator makes a good source of RF for alignment. I had to make a new dial for a Marconi CR100 receiver and so I set the VR500 to give me all the main frequency points up to 30MHz. For example:- 1,1.5,2 and 3MHz were produced by setting the VR500 to receive on 1.465, 1.965, 2.465 and 3.465 respectively. It was a lot easier then manually tuning a sig gen and checking with a counter and the actual frequency was of course rock steady. I am lucky in having the software to program the VR500 and I keep an alignment file in addition to my favourite scanner frequency file.
Les
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Old 9th Jan 2009, 11:16 am   #2
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Question Re: YAESU VR500 as signal generator

Interesting.

How did you extract the LO signal from the scanner, or did you simply rely on stray radiation / leakage?
If you made some sort of direct connection to the LO, was it necessary to use an attenuator?
Was it necessary to examine the waveform to see that the LO harmonic content was low enough to avoid setting the CR100 to a harmonic?

Just curious.

Al / Skywave.
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Old 10th Jan 2009, 2:44 pm   #3
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Default Re: YAESU VR500 as signal generator

Agreed, technically not correct and invalid.
Grey matter (what's left of it) let me down.

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Old 10th Jan 2009, 2:52 pm   #4
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Default Re: YAESU VR500 as signal generator

In the past before, I had the proper gear, I successfully used scanners as signal generators. I would couple the antenna socket of the scanner to the antenna socket of the receiver being aligned via a home made attenuator. Of course there were plenty of harmonics present, but it was generally easy to see whether you were tuned to the right one.

To my mind this sort of improvisation is what amateur radio is all about. It is only fairly recently that second hand synthesised signal generators have become available at prices the average hobbyist can afford.
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Old 11th Jan 2009, 8:09 pm   #5
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Default Re: YAESU VR500 as signal generator

Quote:
Originally Posted by Top Cap View Post
Agreed, technically not correct and invalid.
Grey matter (what's left of it) let me down.

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Whoa! "Agreed"?
My Post - immediately prior to that Post of yours - was certainly not intended to question the validity of your techinque! I was - indeed still am - genuinely curious.
And thank you, Graham, for your contribution.

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