Testing the an/prc-77 radio

Radio Telephone and Telegraph Transmitting and Receiving Equipment
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42GPW
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Testing the an/prc-77 radio

Post by 42GPW » Thu Jul 30, 2020 7:32 am

So I recently traded a guy for an an PRC 77 radio. came with an H 189 handset and the ox box, both antennas, bases and a D cell battery box conversion. Is there a way I can test this locally without another PRC? I can hear it when I turn it on I can break the squelch, but I just want to know that it works. We'll be using it at a Vietnam event in the next month. I was in RTO years ago and humped the 77. Back in the early 90s, I'm just trying to remember how to test this set.

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Re: Testing the an/prc-77 radio

Post by fnp43 » Thu Jul 30, 2020 9:19 am

You can test the transmitter by transmitting to a scanner or fm receiver thats not tone controlled but to receive you will need a tone controlled radio I beleave its a 150 cyl tone if my memory serves me You will need a radio that produces that tone such as another prc77 or a rt524 to check the receive
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Re: Testing the an/prc-77 radio

Post by W. Winget » Thu Jul 30, 2020 9:31 am

The military operator test was check the light, check squelch move knobs...
So I suppose not having a proper scanner, you could place it next to an FM Radio and click the mic. If you hear interference in the radio it means the 77's sending a signal out.
Might not hear voice unless you are matching the freq, but I'd think sitting about 2 feet away any FM radio would be overpowered with the signal coming out of the 77 that close even if not on the 'correct' frequency.
Old UHF antenna on a TV would also work well as you used to pick up those TV stations on UHF think it was Channel 15, 27 and maybe 33 (before cable)
V/R W. Winget

And yes I know nothing about accurately testing the frequency :oops: I just know how to get in trouble by keying a radio next to other gear :lol:
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Re: Testing the an/prc-77 radio

Post by N6CC » Fri Jul 31, 2020 3:42 pm

This transmitter test is pretty easy. Tune your local FM broadcast receiver to 100 MHz. Then tune the PRC-77 to 50 MHz. When keyed, its second harmonic on 100 MHz will be quite audible and provide a good TX comms check. In either the "ON" or "SQUELCH" mode you should also hear the 150 cps transmit squelch tone in the receiver.
Cheers, N6CC

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Re: Testing the an/prc-77 radio

Post by 42GPW » Sat Aug 01, 2020 8:33 pm

I did that. And it interupted the station. How do i know if it will recieve?

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Re: Testing the an/prc-77 radio

Post by GPW43 » Sat Aug 01, 2020 9:32 pm

Hello
just because it threw a signal out doesn't mean it is working on TX 100%; you need to see if voice modulation is there or not.
try to find another fellow with a mil radio. Or buy a used Motorola handheld to have as a pair that will work with 150 kilo hertz tone squelch. pair it up and have a second radio for testing and use.
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