开云体育

Got one with an interesting problem that I thought I'd throw out to the group before digging into it:

The particular '980 in question was my main 20-40-75M rig for a number of years, where it's always worked flawlessly. I moved it into the digi-modes operating position (where tuning is predominately done via CAT control). I fired the rig up today after an extended "off" period of a few weeks and wanted to do a little tuning around the bands with the VFO.

The problem is that the VFO doesn't want to tune reliably after the rig has been on for a few minutes. Going up in frequency results in almost no change, while going down shifts the frequency somewhat...though not as smoothly as a properly working rig. Spinning the VFO knob rapidly allows for tuning - albeit jumpy - in either direction.

The Band Up/Down and 5KHz Up/Down buttons work properly.

I'd seen the condition once before with this particular rig. Changing the memory backup batteries fixed it then, but now is a different story. It's also misbehaving with no batteries installed.

Anyone seen similar weirdness with theirs?

73 - Fred, N8YX

Wow: there have been a few "douzies" submitted recently. This is another one that doesn't trigger anything in particular:

I haven't seen anything like this with my one 1983 rig. BTW, it performed very well in the ARRL Field Day contest last weekened, where I operated a 1D station from my basement. Next weekend I'll do the Marconi CW contest, but I'm going to fire up the Henry (vs going barefoot).

Based on the symptoms, I might suggest the following obvious ones:
1. Clean the opto-interrupter on the VFO knob. I don't "think" that is the case ... but you never know.
2. Measure the power rails that feed the uC/memory and interrupter. It sounds like it could be a bad/leaky cap ... I've seen them where they are getting "borderline", and when they heat up they shift enough to cause issues.

Anyhow, just my two cents, and not even worth that much ...?

--
-Mat Breton, N8TW

Getting back to this one (after spending time on other projects, radio and real-world alike):

If I let the rig in question thoroughly warm up, it won't tune at all in either direction with the VFO - though other tuning methods are fine. Commonality in theory looks to be the voltage fed to the optocouplers or a questionable solder joint on that board itself. Time to dig into the Technical Supplement and see what's what.

73 - Fred, N8YX

Any resolution on this issue? My FT-980 has the same problem. Spinning the VFO knob results more in flickering of the frequency but no significant change in frequency. If I hold the up/down button on the radio or my desk mic, the knob works perfectly (until I let go of the up/down button). Alternatively, I have to manually enter a frequency.

Pete,

None yet. It does seem to be heat-related, though. I can keep the rig in a cool basement and run it for months without issue (which I did as a test until recently). This is going to be an interesting nut to crack.

73 - Fred, N8YX