6400M Tuning Encoder Grinding Sound

WT3J

Hey Folks. Bought my 6400M new in May of 2021 and am generally very happy with the radio for my use, which is about 70% CW and 30% Phone, mostly casual 40, 20, and 10 meters. The only problem I had found was the CW keyer issue with it randomly acting up after having left the radio on for several days. Ran into that while trying to work some contest stations and verifying the issue here on the forum. Thanks for that.

This one is hardware related. All of a sudden a couple of days ago, the main tuning wheel started making grinding sounds while tuning. It would get worse if I spun the dial faster, and seemed a bit worse when tuning up as opposed to down. Did not make a difference if I clicked in on the dial to get the menu up or not. I am preparing to retire out of the country, so any issue with the radio would be at a very bad time for me. So I tried the obvious - got out a hex wrench and took off the dial. Check out the attached photos. Much to my surprise I found a do-nothing bolt stuck in the back of the finger guide of the knob, and held in place with a piece of white tape! The tape had aged and loosened up, allowing it and the bolt to scrape against the tuning encoder! WTH???

Once I removed the obviously unneeded bolt and put the knob back on, it spins perfectly fine with absolutely no resistance or noise. Comments?

John - WT3J

Geoff AB6BT

I believe the nut is there to balance the knob.

WT3J

Interesting. Then it should be held in place better. Thanks.

John - WT3J

WT3J

You are correct. The balance was not quite perfect without it, so I searched the junk box and found a toroid that was about the right size and weight. Holding it in place now with some silicone sealant. Gotta be better than tape that can age and fall off.

I guess the knobs are drilled out for the finger slot without any compensation, maybe by a 3rd party. Did not expect that...

Geoff AB6BT

Sound like a good and more permanent fix.

Mike Steventon

Just today noted the grinding sound from tuning knob on my 6600M. I also discovered the "magic nut" taped into a recess in the knob. Talk about heath-robinson fix!!

Anyway, I have retained the nut, but used a far more sticky tape to hold it in place. All working as new!

Thank you for placing this little problem on the forum.

73.

Mike G4GWH