Kenwood TK 3101 Issue

[malcolmblalock]

Hello out there. I'm experiencing a problem with my bike to bike radio, a Kenwood TK 3101 to Autocom. The Kenwood has the power adapter so that the radio is powered through the Autocom to the bike. No battery is used.

 

My problem is that when I'm transmitting, after just a second or two of transmission, I get a high-pitched whine in my speakers, and the transmission is cut off so that the other person hears nothing from me while the whine is taking place. This happens whether the engine is running or not.

 

I'm wondering if the whine I hear is the same as one hears when the battery (Kenwood) is too weak to transmit. If that's the case, I'm wondering how the voltage drop is significant enough to trigger the tone. I do have one "extension" cable between the radio and the Autocom cable.

 

I've used this combination previously for many thousands of miles with no issue. However, this spring, when I've tried to use the radio, I get the whine (or tone). The reception is fine, it only happens when transmitting.

 

I've checked and re-tightened the power leads to the Autocom (powered through a Centec box), and coupled and uncoupled all of the cable leads to make sure I have good contact.

 

Any ideas on what's causing it or what to do about it???

[bobbybob]

Hook the radio up to a different 12V supply, from another battery or direct to the bikes battery, then try it. If it works fine after eliminating the Autocom from the loop, you'll know its not the radio.

[malcolmblalock]

Bob, the 3101 operates on 7.2V DC, so I don't want to fry it by connecting directly to 12 volt source. Additionally, even if I wasn't worried about that, I don't know how to do it since power is carried by the Autocom cable.

 

I did try the radio with battery, and it works just fine. No tone; LED stays Red (which it should) when transmitting.

 

I actually had this happen once before when I tried out another Autocom model. It did this; I changed back to the current Autocom, and it worked correctly again. But something changed over the winter.

 

Other ideas?

[KDeline]

Turn the volume down on the Kenwood.

[johnlt]

Even though they can been hooked up, not all of the Autocom models will handle the current requirements of the TK3101. In addition, some Autocom models supply 12V and the Kenwood only uses 7.4 so I'd recommend you modify the adapter with a voltage regulator. Maybe Mikko will chime in. He's pretty much an expert at this setup.

[malcolmblalock]

Yes, I understand that not all models of Autocom can handle the Kenwood 3101 with the power adapter. However the Autocom on the bike managed the same radio for well over a year with no problems until this spring. I'll try KDeline's suggestion to turn down the volume tomorrow to see if that helps.

[malcolmblalock]

KDeline, I tried it today with the volume lowered, and the tone is still present. It made no difference at all.

 

Other ideas?

[KDeline]

KDeline, I tried it today with the volume lowered, and the tone is still present. It made no difference at all.

 

Other ideas?

 

 

When you tried the Kenwood with the battery, did you do it as stand alone or through the AutoCom? What is the red transmit light doing during this noise making? Also if you put a meter onto the terminals of the AutoCom/Kenwwood battery adaptor, I think it is 12 volts, don't think there is a step down circuit in there. I could only use my Kenwood 1301 with a PRO-7, never any newer unit as that is the exact problem I had. Even with the PRO-7 I never could run full volume on the Kenwood.

[FlyingFinn]

What Autocom model, what "battery eliminator" model and what other equipment are hooked up to the Autocom?

 

It's also possible that one or another current carrying wire connection has got little loose or oxidized over the winter.

At high current load the voltage drop might be too high.

 

Try to disconnect all the cables, clan off any visible crud and reconnect nice and tight.

 

--

Mikko

[malcolmblalock]

I have a feeling that I have an issue with current drop. I'll pop off the Tupperware and clean all connections this weekend. I'll report back after I've done that...