TK-7150 spontaneous transmit problem

[KA7JUR]

My employer has more than 30 Kenwood TK-7150 transceivers installed in a variety of vehicles, but mostly passenger cars. The problem is that several times or more each week there will be one or more of these radios that will randomly transmit what seems to be DTMF tone zero until the transmitter times out or the user powers off the radio. When this happens, the tone can be heard in the speaker giving the user the impression that he/she is hearing another unit sending the tone. However, often the user will notice the red transmit light while hearing the tone and then manually power off the radio. As soon as the radio is powered back on, the problem goes away for days, weeks, or months. However, with this many radios in the fleet, there seems to be very little ability to predict which of them will be the one to cause a problem on any given day.

There is no predicting when these spontaneous transmissions will happen. Some times it starts while the vehicle is moving (speed and roadway type don't seem to matter) and other times it will happen while parked and unoccupied.

There are several different versions of firmware spread across the fleet. We have not been able to correlate the problem with a single version. The microphones don't have DTMF and we are not using any DTMF tone feature or ANI in the radios. The overall feature programming has been reviewed, but the cause is not apparent and reprogramming the radios (albeit with our same frequencies) has not helped. Also, the problem happens regardless of which of channel a radio is set to use.

If anybody else has experienced this, I would really like to know if you found a solution.

Thank you for reading this.

 

[icom4ever]

TK-7150 Tone issue resolved

While this thread is certainly long in the tooth, here in 2016 I have a customer with this exact same problem. When a vehicle radio is powered on, and the vehicle cranks its engine, dropping the voltage to the radio, the radio appears to transmit a DTMF "0" for roughly 90 seconds (on a random basis).

Through trail and error, I believe the issue is related to firmware version 1.05, and specifically occurs on a random basis at radio power on.

The current firmware version is 1.07. I found that in the fleet of about (25) TK-7150 mobiles, about 10 were at version 1.05, and the remainder a mix of 1.06 and 1.07. After upgrading all units to version 1.07, I can say with good confidence that the problem has been resolved. For well over a month now, the problem has not been reported, whereas it was occurring on a weekly basis before.

The Kenwood service manual provides good instructions on how to perform the upgrade, and the firmware is available to Kenwood dealers on the KW B2B website.