FT8800 slight hum on TX

[62Truck]

Recently my FT8800 has started making a hum noise on transmit. It's not obnoxious or anything just slight little hum. If I place my hand on the radio or the power supple the hum goes away. I have tried using two different power supplies also. The hum happens with both. I have also tried using another radio a Motorola CDM 1250 and that does not hum at all on either power supply.

What should I be looking for? My next step is to get a dummy load and see if the hum is till there. I'm assuming their might be a grounding issue?

 

[N4KVE]

While this probably isn't your problem, my friend had a Yaesu FT-90 that hummed while in his house. He turned off the lamp on his desk where the radio was, & the hum went away. Have you tried the radio in a car, or connected to a battery?

 

[scottyhetzel]

Recently my FT8800 has started making a hum noise on transmit. It's not obnoxious or anything just slight little hum. If I place my hand on the radio or the power supple the hum goes away. I have tried using two different power supplies also. The hum happens with both. I have also tried using another radio a Motorola CDM 1250 and that does not hum at all on either power supply.

What should I be looking for? My next step is to get a dummy load and see if the hum is till there. I'm assuming their might be a grounding issue?

Sounds like the final amp is loose... Pull power and tighten all the inside nuts and screws.....not too tight.

 

[62Truck]

Sounds like the final amp is loose... Pull power and tighten all the inside nuts and screws.....not too tight.

I'll give that a try. But it is happening on both 2 and 70

 

[k3cfc]

Recently my FT8800 has started making a hum noise on transmit. It's not obnoxious or anything just slight little hum. If I place my hand on the radio or the power supple the hum goes away. I have tried using two different power supplies also. The hum happens with both. I have also tried using another radio a Motorola CDM 1250 and that does not hum at all on either power supply.

What should I be looking for? My next step is to get a dummy load and see if the hum is till there. I'm assuming their might be a grounding issue?

Take your digital volt meter and put it on the ac scale and see if you have more than .05 volts on transmit. if so change the bridge rectifier and all the caps. but first ground the radio to the p/s this easier see if the hum goes away. look for loose screws in the p/s and the radio. look real close at the board in the radio for either a crack or a bad solder joint.


Hope this helps.

K3CFC

 

[62Truck]

Guys thanks for the info. I actually traced the problem to the microphone.