TS-520 VFO

[KE4IZA]

I have a TS-520 in superb shape with the exception of the VFO.  The VFO dial does work fine but when rotated has a feel of being detented in several spots around the dial.  It is hard to describe.  If I stop on one of these ares the vfo will want to roll forward or backward several khz.  It definitely is mechanical.  dial is solid and feels normal except for what I am describing.  Anyone ever experienced this.  I am thinking maybe VFO needs to be removed, cleaned and greased but I do not know if after I remove it it can be cleaned and greased.

HELP!

[K6LO]

The '520 VFO is a planetary gear system, and does not have a ball drive like the older Yaesu radios did.  I would clean it and regrease it with a high vacuum grease if it looks as if it needs it. 

73 Luke

[KE4DRN]

hi James,

the capacitor shaft has a ball bearing at the front
where it passes out of the vfo metal enclosure aka 'can'.

the internal contact at the rear of the vfo can get dirty,
these radios do not like to sit idle for long times,
info on the following group on how to clean that contact

http://groups.yahoo.com/group/TS-520_820_530_830/

73 james

[KE4IZA]

Jim, thanks for the heads up on the TS-520 group.
I was told that the VFO is not worn out but someone has been in there tigtening things up.  I was told that I need to back off the bearing nut and I will immediately feel the difference.  I can not get any further info.

Where is this bearing nut?  Any idea?

73

[KE4DRN]

hi Jim,

the lube in the shaft ball bearings may be dried out,
you can access it via the side cover in the photo,
use 90 deg. screwdriver and a drop or two only of
Triflow will free it up.

http://www.k4eaa.com/vfo.jpg

not sure about the nut for the vfo, I would try
the above before removing the vfo.

73 james

[N6AIR]

My TS520 had the bad VFO symptoms. It was very hard to tune; the audio sounded scratchy and it jumped all over the place.

Blowing compressed air into the top hole of the VFO did nothing.

I don't have a right angle screw driver so it was hard to take off the side door of the VFO. I did it with needle nose pliers, one fraction of a turn at a time.

After I got the door off I sprayed DeoxIT D5 with a lot more than I had to. Then I let it sit overnight so I was sure it was dry.

In the morning, I fired it up and it took care of the problem 100%.

Now, am I supposed to apply some sort of contact grease to maintain it?

Well, if I have problems again, I know that the DeoxIT D5 will take care of it.

[KE4DRN]

hi Robert,

the Deoxit is all you need since the vfo is working properly.

I picked up a second used 520, the drive control bearing was
very tight, I put a few drops of triflow into it and the next day
the drive control was smooth as if it was new out of the box.

73 james