Programming 2m/70cm Repeaters into a GMRS Handheld (monitoring only)

[KK7RQX]

When programming repeaters into a GMRS radio (for monitoring), is it necessary to program the PL tone on the input (receive) side of things, or should that be left off/blank? Seems to me that by programming the PL tone into the radio receive, you will hear anything traffic using the PL tone, but that's it. If I leave the PL tone off/blank, then I would hear all traffic on the repeater regardless of the PL tones that traffic is using.
Is that right?

 

[AK9R]

Using CTCSS, aka "PL", on a receive channel is not necessary unless you are trying to block your receiver from passing the audio of other transmissions on that frequency that don't use the CTCSS tone you programmed.

Example: Radio programmed to receive an RF frequency of 146.970 MHz with a 77.0 Hz CTCSS tone. If the receiver hears a signal on 146.970 MHz with a 77.0 Hz tone, the receiver's squelch will open. If the receiver hears a signal on 146.970 MHz with a 107.2 Hz tone, the receiver's squelch will not open. However, if you don't care to block the signal with the 107.2 Hz tone, program the radio with no tone, aka "carrier squelch", and the radio will hear every signal on that RF frequency that has a carrier strong enough to break the squelch.

 

[hill]

Would leave the receive PL off for ham repeaters. Many don't use a tone on the output,

 

[k9wkj]

Would leave the receive PL off for ham repeaters. Many don't use a tone on the output,

I dont personally know of any repeaters that dont transmit tone or DCS
and all 8 that I manage most certainly do

 

[hill]

In my area it's hit or miss with the tone being transmitted.

 

[N4KVE]

While some ham repeaters don’t transmit a PL tone, they still pass the PL tone that the users‘ radios are transmitting to get into the repeater.

 

[prcguy]

While some ham repeaters don’t transmit a PL tone, they still pass the PL tone that the users‘ radios are transmitting to get into the repeater.

They should never pass a PL tone through a repeater, there are audio high pass filters in the repeater audio chain to prevent this.

 

[hill]

They should never pass a PL tone through a repeater, there are audio high pass filters in the repeater audio chain to prevent this.

Agree.

 

[N4KVE]

They should never pass a PL tone through a repeater, there are audio high pass filters in the repeater audio chain to prevent this.

Maybe they shouldn’t, but I know for a fact the Wellington UHF ham repeater does. I have PL decode on, & I can still receive it.

 

[AK9R]

Maybe they shouldn’t, but I know for a fact the Wellington UHF ham repeater does. I have PL decode on, & I can still receive it.

Which only proves that the repeater transmits a PL tone. It does not prove that the repeater passes through a PL tone.

Usually, the repeaters receive circuitry, or an external CTCSS decoder, listens for the incoming tone and then filters it out of the audio. You generally do not want a low frequency, low level tone running around in repeater controller audio switches, DTMF decoders, and other circuits in the audio train. On my repeaters, the transmitted CTCSS tone is injected just before the audio signal goes to the modulator. That transmitted tone could be completely different from the received tone.

 

[prcguy]

Which only proves that the repeater transmits a PL tone. It does not prove that the repeater passes through a PL tone.

Usually, the repeaters receive circuitry, or an external CTCSS decoder, listens for the incoming tone and then filters it out of the audio. You generally do not want a low frequency, low level tone running around in repeater controller audio switches, DTMF decoders, and other circuits in the audio train. On my repeaters, the transmitted CTCSS tone is injected just before the audio signal goes to the modulator. That transmitted tone could be completely different from the received tone.

One way to prove it would be change tx tone on your radio and see if the repeater output tone follows.

 

[prcguy]

One way to prove it would be change tx tone on your radio and see if the repeater output tone follows.

I might add that if the test shows tone passes right through the repeater, then boycott that repeater until the owner wires it up properly.