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Some information about Yaesu's "PR Frequency" function.

Guest BA7NFW

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Hi, BA7NFW here.

Background infomation

When I searched for "No-communication squelch" function, which you can find on most yaesu radios, I came across this post ('cause it shows up on google).

Basically we can't make this function work, not even have an idea why this function exists when TONE Reversed mode already works fine.

I had the same confusion, and the question wasl unresolved. (btw, can someone post under that question just to tell Marc I have an answer now? I'm not living in FCC regulated territory and don't have a GMRS call sign, hence not able to register here)

tl;dr  PR Frequency function is used for the Japanese railway radio repeaters.

From the FT5DR/FT5DE Advance Manual, PR FREQ is a frequency of 300-3000Hz used for Reverse CTCSS Decoder:

User Programmed Reverse CTCSS Decoder The tone signal frequency can be set at 100 Hz intervals between 300 Hz and 3000 Hz to mute the audio when receiving a signal containing a CTCSS tone matching the programmed tone.

So it's natural to think, PR FREQ = user Programmed Reverse ctcss decoder FREQuency.

And that's the tricky part. Took me about half-day researching until I checked the Japanese version of the manual.


So, PR here actually means Private Railway(私鉄).

The Japanese Railway (JR) and other railway companies (PR) use a system of radio repeaters. When the repeater is standby and no one is using it, it keeps sending a monotone of 2280Hz (for JR, PR may use other tone between 300-3000Hz) to represent that status. If not specially handled, this may keeps your squelch opened.

And that makes sense, this function will cancel a certain tone carried in FM mode, and it's not a standard CTCSS tone signal, therefore a separate function was implemented.

I highly suspect if this function is actually useful outside Japan. And the terrible translated manual just makes everything more confusing.

That's all.

Ken (BA7NFW)

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