Gonset Communicator RX tuning reducer.

[WA1LGQ]

I am working on reviving a Communicator III 6M found at the Vintage Radio and Communications Museum of CT at their last quarterly swapmeet. Got it going but the rx tuning speed reducer is slipping. Is there anything that can be done to fix one of these or is it a good luck finding another one type of situation? I suppose I can just epoxy the inner and outer shafts together and make it work that way if I have to, but it won't be as nice. It needs a restring job anyway, so its all apart at this time.
Thanks.............Larry

[MikeKE0ZUinkcmo]

That style of drive depends on friction, differential, in that the total rotational friction of the various pulleys and tuning capacitor must be less than the friction of the 2 or 3 turns wrapped around the tuning shaft.    THis type of "drive" has been around for almost a century and is very dependable, so long as it is in good repair.


The dial string and tuning shaft it is wrapped around must be dry and not have any type of lube, wet or dry, applied to it.  However the shafts the pulleys rotate on should have a touch of lube unless they and they are of brass construction.    Additionally, the bearings and races of the tuning capacitor must be very CLEAN, with only a touch of oil. 

Additionally, the grounding fingers, which ground the capacitor shaft at both ends of each section must be clean as well.

 

[WA1LGQ]

Thanks Mike, I will clean up the bearings and string guides more thoroughly and blow them out with the compressor, re-oil, re-string and see what happens.
Larry

[W3RSW]

Spring tension may have lessened over the years too. Exact replacements may be hard to find so slightly stretching them beyond there original length or stringing under more tension than original is dicey but might be doable.

[WB6NVH]

The coaxial reduction drive assembly on the III series is a known issue and you will find many of them that have been glued or soldered together.  The usual precautions of making sure all the bearings and so forth are well lubed and clean are usually not enough in this specific case.  I have one on the good intentions pile right now where someone has soldered the drive together (!) so I will be experimenting with mine as well, after I correct the mess...

[WA1LGQ]

Yeah, I just went ahead and glued the thing. It works quite well like that. The string was not in great shape, so the whole string and dial mechanism was dissembled, cleaned, and put a new string on it. Works quite well. Cleaning and re-lubing the bearings did not fix the problem, but it did help a little. With a bit of restoration, new electrolytics, tube replacement, relay cleaning and general contact cleaning and tweaking of tuned circuits the thing is doing well. Puts out about 6 watts. I had to steal a 2E26 from a HA-460 though. There was a hamfest this  morning in Chicopee, MA, but could not find any 2E26's. In fact not many tubes at all, or anything else that I was looking for. A handful of the 6M AM gang were there though.
Larry