SX 28 angst

[KB2WIG]

I'm in need of some opinions regarding the following....

The sx 28 bandshaft is composed of two seperate pieces joined by a insulated shaft coupler. See the atached photo. The shafts ends are cut flat on two sides the length of the shafts. Both have a 'third' side machined flat approx. 1/4 in. so the set screws can set.
  I can't see any reason for the insulated piece; i'll guess that it was cheeper somehow. Anyways, one side of the piece has developed a crack so the shaft wobbles a bit when moved.  I'b going to see if there's a way i can get a normal, uninsulated shaft for this thing. The problem is in the "third flat".  They are not lined up so a normal coupler set screw can be used;  one side will end up on a 'round' part.

OH, yeah.....  When I recapped this thing a few years ago, I left out a little brass tension ring (looks like a thin washer) and can't remember exactly whar its sposed to go....

Any suggestions?


klc

[The Slab Bacon]

Yea, use the right coupler.....................

That one goes somewhere else!!
The one for the bandswitch is not insulated and is a little beefier. It has a metal "floater" instead of the phenolic one that you have in the picture. It was designed to compensate for / allow for mechanical misalignment only.

[KM1H]

And even the original metal ones break, Ive seen many with globs of solder repairs.

The old Millen couplers offered many choices and you can even use a solid one with a 4 screw lockdown if everything is in alignment. Do that by barely loosening everything and attach the coupler and then let things center themselves. It doesnt always work as your fighting production tolerances.

A pic of that ring would help.

Carl

[KB2WIG]

  " That one goes somewhere else!!   "

Dats the one I pulled out 'o the radio. It's kinda odd in the set screws positions. Looking at the coupler as a clock face, One side is 11:35, flip it onto the other side and its 2:50


"...use a solid one with a 4 screw lockdown if everything is in alignment. "

Thats probably how it'll get done.....

"A pic of that ring would help."

My wife has, what I in error call, my camera.... so, the crappy phone camera.

thanks guys,

klc 

[Opcom]

I do not know where the 'washer' brass thingie goes. I'll look into my set since it is presently apart. 

As for the shaft coupler in your images, having the unusual offsets, it is the same as the one on the crystal filter variable capacitor. That one broke on my radio and I replaced it with another kind. I do not know why it may have broken.

Perhaps you may swap the crystal filter one for the broken band-shaft one, and use a regular insulated one for the crystal filter capacitor shaft.

[Opcom]

Two notes:

1.) my SX-28 has one solid shaft for the entire bandswitch. There is no coupling.
2.) The only obvious places for that washer I could see are against the front panel on the headphone jack and on the rear panel where the phono input jack is. It really looks like a 1/4" jack sort of thing. If not, I have no idea. I did not see any other places.

Patrick

[Todd, KA1KAQ]

Between Slab and Carl you should get it figured out, Kevin.

One thing I'd strongly suggest for future projects is taking copious amounts of photos of everything before, during, and after dis-assembly. In today's world of digital cameras, it takes very little time and it can really save your bacon when things suddenly don't make sense. I've been able to reference old photos that I didn't even take for that purpose to solve mysteries. Very handy.

[KB2WIG]

P,
Thanks for looking. I know it goes onto the bandswitch shaft......

T,  Yes , the photo is the way to go....  when I did the work, I drew heathkit like drawings of most of the unit. Naturally, I didn't note where the thingie went.

Now, the local osc won't osc on more than band, so thars somre head scratching to do....
I'll think i'll go play with the vk2.

klc