I purchased a very nice condition FT-1000 D 2 weeks ago. It performed well when I first installed it in my shack. Now it has developed a hum when I transmit. It seems to me like a ground loop problem, so I took the covers off, and went about tightening all ground earthing screws, paying particular attention around the transformer. I also put a snap-on ferrite around the long wires going to the on/off switch. I put it all back together, but the loud hum is still there. It is not there on receive - only when I transmit, and when the built-in power supply is under load. The hum is loud externally, and also gets transmitted with the output signal. The more power I run, the louder the hum becomes. No external equipment is connected, just the power cord, antenna and a very good earth cable going to the ground lug. Any advice please ?
Sorry, after having posted the previous post, I decided to try one last thing. I powered up the rig - with the covers off, noting that the hum was still very loud on TX with the covers off. I then proceeded to fiddle with the wires coming from the output of the transformer - 48 volt dc ?. By fiddling with these 4 DC output wires, I found that they were making poor connection in the plug that they terminated in. By moving these wires and plug, I was able to totally remove the hum. While moving the wires, I noticed a spark inside the connecting plug, further indicating that there was a poor connection. I removed the plug, crimped each of the 4 connectors, and re-inserted the plug - now they were making proper contact, and no more hum.
Location: IO90OT 7 Southover Way, Hunston, West Sussex PO20 1NY
Posts: 23
Quote:
Originally Posted by ZS5J
Sorry, after having posted the previous post, I decided to try one last thing. I powered up the rig - with the covers off, noting that the hum was still very loud on TX with the covers off. I then proceeded to fiddle with the wires coming from the output of the transformer - 48 volt dc ?. By fiddling with these 4 DC output wires, I found that they were making poor connection in the plug that they terminated in. By moving these wires and plug, I was able to totally remove the hum. While moving the wires, I noticed a spark inside the connecting plug, further indicating that there was a poor connection. I removed the plug, crimped each of the 4 connectors, and re-inserted the plug - now they were making proper contact, and no more hum.
73
John, ZS5J
Hi
I was going to mention before I saw your second post that I have an IC-706 which did exactly the same thing and I concluded it must be the power connections so made sure they were well secured and no more hum. I always now check that before anything else. Well done glad you got it sorted.
We appreciate your support.
FT-1000 D transformer hum on TX
THE HUM HAS BEEN RESOLVED
Linear Mode
