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9th Jan 2009, 2:26 am | #1 |
Octode
Join Date: Mar 2006
Location: Watford, Hertfordshire, UK.
Posts: 1,270
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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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9th Jan 2009, 11:16 am | #2 |
Rest in Peace
Join Date: Jun 2006
Location: Chard, South Somerset, UK.
Posts: 7,457
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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. |
10th Jan 2009, 2:44 pm | #3 |
Octode
Join Date: Mar 2006
Location: Watford, Hertfordshire, UK.
Posts: 1,270
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Re: YAESU VR500 as signal generator
Agreed, technically not correct and invalid.
Grey matter (what's left of it) let me down. Mod: Please delete this thread
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Whether the Top Cap is Grid or Anode - touching it will give you a buzz either way! |
10th Jan 2009, 2:52 pm | #4 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,193
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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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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
11th Jan 2009, 8:09 pm | #5 | |
Rest in Peace
Join Date: Jun 2006
Location: Chard, South Somerset, UK.
Posts: 7,457
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Re: YAESU VR500 as signal generator
Quote:
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. Al. / Skywave. |
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