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Author Topic: RF Voltmeter  (Read 2363 times)
W4JJA
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Posts: 23




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« on: April 15, 2012, 05:21:37 PM »

Where can I buy a RF voltmeter at a reasonable price?
Tnx,
Jack
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K2OWK
Member

Posts: 1064




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« Reply #1 on: April 15, 2012, 08:53:51 PM »

Hello, EBay has over 30 listed at various prices. Check them out, you pay your money and hope for the best. Some come with return warrentees and some are sold as is. I set up my complete test bench with equipment purchased from EBay. From a new frequency counter to a used Tektronix scope.

         This is just a suggestion, you can also put used RF voltmeter in a search engine and see what it comes up with.

73s

K2OWK
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W5FYI
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Posts: 1046




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« Reply #2 on: April 15, 2012, 11:46:59 PM »

There's nothing cheaper than making a homemade RF probe for your own voltmeter; a simple diode and a 0.1uF disc capacitor. Your voltmeter will show peak RF voltage, minus the diode's voltage drop, but that can be converted to RMS volts by multiplying by 0.707.  GL
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G3RZP
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Posts: 4627




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« Reply #3 on: April 16, 2012, 01:04:38 AM »

Depends what you want out of an RF voltmeter. Voltage range, frequency range, accuracy, input impedance.....

The old VTVMs with a tubed RF probe could typically take up to 300volts at lower frequencies - <100 MHz -  and had a minimum FSD of about 300 mV. Useable typically to 500 MHz, and the spare tubes are $50 if you can find one. Input impedance ran to about 2pF in parallel with hundreds of kohms at LF, dropping as the frequency goes up.

The Racal solid state one is about 100K input Z, from memory does about 1 GHz, and needs special attenuator probe tips for  higher voltages and doesn't go up to 300 volts. A HP Vector voltmeter goes up to at least 1 GHz, depending on model and is very sensitive, but can't handle high voltage.

So the question boils down to "What do you want to use the RF Voltmeter for?"
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