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Old 08-01-2012, 06:27 PM
6GH8cowboy 6GH8cowboy is offline
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JFD Field stregnth meter

I found a JFD 7200 Field Stregnth Meter in a Pickers shop and aquired it for the tidy sum of $10. I figured the parts alone would be worth that much if it turned out to be a big fail. When I replaced the batteries it was indeed DOA. However I plinked around with a meter and checked a few things and it turned out to be the meter movement connections were loose on the pcb they were directly screwed to.
Does anyone have a scan of the user manual or tips on use in the real world. I pluged a headset and can hear the digital 'noise' on UHF and audio of the local FM stations on VHF so I believe it's functional. Not nesseraly calibrated at this moment in time.

There was also a lot of antique meters from the 20's on up. These things look like they could measure milliamps or a pound of coldcuts. Big wooden, heavy, old.

Anyway any tips on the 7200?
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Old 08-01-2012, 06:32 PM
bob91343 bob91343 is offline
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That looks like a nice meter indeed. I'd love to play with it. Calibration shouldn't be difficult.
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Old 08-03-2012, 12:05 PM
6GH8cowboy 6GH8cowboy is offline
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Advise on use of the JFD-7200

Any old cable or MATV techs that can advise on the use of the JFD signal strength meter. Shortcuts, observation, practical meaning of measurements. I've figured out the basic operation and now need some real world application besides the relative strength of a signal. I can identify the local digital signals and listen to FM radio. For field measure what kind of ant do I use? Vert, dipole, cut to length dipole, tin can?

Someone throw me a bone here. The wisdom is out there somewhere.
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Old 08-03-2012, 02:35 PM
bob91343 bob91343 is offline
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Isn't there a built in antenna? Read up on field strength measurements; typically you use a one meter long antenna and then the readings will be direct in microvolts per meter. For VHF that gets a little long, so you can use a 0.1 meter antenna and multiply readings by 10 to get field strength. That's only about 4 inches so your technique is very important. You orient the antenna for maximum reading.

The only purpose of the instrument is to measure field strength; they were typically used to determine station coverage. The tricky part is to identify the station.

There should be a calibrate function; your picture isn't clear enough for me to see.
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