Recently I was having problems sending Baofeng DTMF tones to my IRLP board. This only seemed to happen when I was approximately 100 yards, or more, away from the base unit/receiving antenna.

Ask For Help

One Sunday I was listening to the WIN System Tech Net (IRLP Reflector 9100), and I inquired if anyone knew anything about this problem I was having. Shorty (K6JSI) suggested that I may need to adjust the DTMF decoder potentiometer inside the RX radio. Ron (WB6IAG) suggested that my IRLP audio levels might be wrong. I continued to do more research and came across a possible solution from the Radio Reference website.

What Was Happening

As it turns out, the Baofeng HT radio I was using to send the DTMF tones to the IRLP board was the problem. While pressing the PTT + DTMF key(s), the mic does not mute. This can cause the mic to pick up any sidetones from the speaker and will overdrive and/or distort the transmitted tone(s).

The Solution

The solution is in the Baofeng’s menu settings. The menu #16 (DTMFST) setting needs to be set to “OFF”. This is accomplished by following the steps below.

Press the following buttons on your Baofeng UV-5R:

Menu > 1 > 6 > Menu > 0 > Menu > Exit

I have not had any further problems since adjusting this setting in the radio.

Note: It is worth mentioning that SOME of the Baofeng UV-5R’s do not transmit the DTMF tone “D”. The “0” tone is transmitted when the “Exit” button is pressed. This is a firmware problem and can not be fixed.

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