Motorola T7200 won't receive from other radios?

[Epeescott]

My two T7200s will communicate with one another, and when I transmit on them, my other radios can hear them fine.

However, when I transmit on my other radios, the T7200's won't receive.

Anyone have any ideas why?

[ffexpCP]

Probally due to a PL tone.

[canav844]

Yeah are they set on the same freq/Channel *and* subcode?

[Epeescott]

I verified in the manuals of the radios that the frequencies are indeed the same on all the radios, both for Tx and Rx (why transmit might be different from receive, I don't know)......

Subcode? I don't know what that is, unless it is a encrypt type feature.

What is a PL Tone?

[gewecke]

I have one of these also. If mine is set to scramble,it doesn't receive another radio if it's a different make.
You might check that too?
N9ZAS.

[Epeescott]

It isn't the encrypt feature.

The T7200, being a better radio, has an "Interference Eliminator Code". Default is one, but setting it to zero will enable other, cheaper radios to hear you.

[Epeescott]

So, thanks to everyone, and I am looking forward to learning more here!

[n1das]

Originally Posted by Epeescott

It isn't the encrypt feature.

The T7200, being a better radio, has an "Interference Eliminator Code".

The "Interference Eliminator Code" is a fancy name for a PL tone.

Code #1 = 67.0Hz This appears to be Motorola's default tone.

Default is one, but setting it to zero will enable other, cheaper radios to hear you.

Setting the code to zero turns off the feature and your T7200s are listening in carrier squelch mode (CSQ) and they won't be encoding a tone on transmit. Also, cheaper radios will still hear you, whether or not you're using the "interference eliminator code" feature. Using the tone-coded squelch system in your radios does not make your transmissions "private". Everybody else can still hear your transmissions. It simply relieves you of having to listen to all the other chatter on the channel that you're sharing with others. Your T7200 is actually still receiving those other transmissions, the difference is the radio will stay muted on those transmissions that aren't transmitting the same subaudible tone your radio is set to decode. Your radio will only unmute the speaker audio when it hears transmission(s) transmitting the correct tone. A more accurate name for this feature should be "Inteference IGNORING codes".

See also: http://wiki.radioreference.com/index.php/CTCSS

[gewecke]

True...as posted above. Although I've met 2 other people with the T7200 and neither were aware of the inversion scrambling feature,or the microphone sensitivity feature. Fyi.
N9ZAS.

[n1das]

Originally Posted by Epeescott

It isn't the encrypt feature.

It isn't encryption either. The scramble feature is simple analog audio inversion scrambling....not secure at all.

[n1das]

Originally Posted by n1das

See also: Continuous Tone-Coded Squelch System - The RadioReference Wiki

The T7200 only has the standard 38 CTCSS/PL tones. It has no DCS/DPL capability.

See also: http://wiki.radioreference.com/index.php/DPL

[gewecke]

Thanks dave. We knew this already.
N9ZAS.

[Epeescott]

Thanks - I didn't mean actual encryption as opposed to simple scrambling.

Also thanks for the explanation of the PL tone and CTCSS. I'm really new to this stuff.