Heathkit DX-100 Transmitter coarse/fine loading control

[kq6xy]

I am working on a DX-100 that has not been used for many years, and noticed that that the fine tuning (inner knob) turns the outer knob coarse tuning. I can't seem to get the fine tuning shaft to turn independently from the coarse outer shaft.

Is this a show stopper? Or can I tune with just with the coarse control?

And how might I fix this?

73,
de Larry, kq6xy

[W1RKW]

need to remove the knobs then lubricate the inner shaft.  it's gonna take some repetitive work to loosen it up.

[W1ITT]

My latest favorite lubricant/penetrant is DeepCreep, available at the auto parts store.  It's an aerosol, but I would spray a bit onto a Q-tip and let it wick in, then let is sit for hours or days.  Any bearing surfaces from the rear should be treated as well, but use caution so as not to get it on any phenolic wafers as it might turn them to mush.
I've had good luck with DeepCreep on stuck bolts on the tractor, all the way down to little parts.  And it smells a lot better than PB Blaster, WD40 and the rest.
73 de Norm W1ITT

[Dave K6XYZ]

Yeah that PB Blaster stinks SOOO bad that the XYL will make you live in a tent in the back yard no matter how many times you scrub down with a wire brush!
It’s very difficult to get off of skin or anything else.
Don’t get any of it on a radio or IT and YOU will be in that tent!!

[KD1SH]

Indeed, PB is pretty much the foulest smelling concoction I ever have occasion to use around the shop, and I resist any thought of using it on gear that will eventually reside up here in the shack. My wonderful wife is lovingly tolerant of pretty anything to do with my radio hobby - even goes to the hamfests with me - but even a single 4-40 screw treated with that stuff will have her hyperventilating. The best thing I've found for removing traces of PB after it's done its work is CRC Brake Parts Cleaner, which evaporates without leaving any odor of its own.

Yeah that PB Blaster stinks SOOO bad that the XYL will make you live in a tent in the back yard no matter how many times you scrub down with a wire brush!
It’s very difficult to get off of skin or anything else.
Don’t get any of it on a radio or IT and YOU will be in that tent!!

[W3MMR]

Mine doesnt turn independently. Theres an update from heathkit that gets rid of the switched in caps and uses a 3 gang variable condenser now instead... 

[AJ1G]

When I first was checking out the DX-100 that came my way last year, I noticed that the little red vernier loading knob would not rotate, and the coarse loading outer knob did not appear to hit any detents, even though it rotated (and took the red vernier knob along for the ride).  After pulling the chassis out of the cabinet, I found the three section broadcast type variable installed instead of the stepped fixed cap/ vernier cap arrangement.  I didn’t know if the Heatkit “field change” kit included a new single knob, whoever did the change on my transmitter somehow has attached to original large and small coaxial knobs together.  It appears that some hammie hambone in the past tried to “free up” the small red vernier knob with a pair of vice grips, the fluting of the knob OD is all chewed up.

I have read that installing the loading cap field change was considered by Heathkit as making the transmitter the DX-100A.  Does anyone know if any DX-100s were sold by Heathkit with the variable cap loading as part of a complete kit?  The DX-100B included the variable cap loading along with a number of other mods.

Another oddity of my DX-100 is that the coupling on the driver tuning cap shaft closest to the cap is located directly above the rear-most of the four crystal sockets for
crystal controlled operation, which precludes using that socket.  Looks like a design error, does not look like the shaft was incorrectly installed.  Do other DX-100s have this issue?

[WB8PFZ]

My coupler is a half inch behind the VFO cabinet. Plenty of room. I wonder if someone changed it for some reason? Mike

[W3SLK]

KQ6XY said:

I am working on a DX-100 that has not been used for many years, and noticed that that the fine tuning (inner knob) turns the outer knob coarse tuning. I can't seem to get the fine tuning shaft to turn independently from the coarse outer shaft.

Is this a show stopper? Or can I tune with just with the coarse control?

And how might I fix this?

73,
de Larry, kq6xy

For things like that, we use Kroil, (or as known in the trade as Weasel Piss or Millwright's Aftershave). It is extremely effective, however if you get it on 'your person' it is difficult to get rid of the 'aroma'.