[Hammarlund] Hammarlund Digest, Vol 172, Issue 4

[Richard Knoppow]

    Well, the problem is that the dial is part of the tuning 
mechanism. The dial is driven by a friction wheel on the shaft 
with the tuning knob and in turn is fastened to the shaft of 
associated tuning capacitor. When this is working properly the 
tuning is very smooth and is completely free of any play or 
backlash. The Super-Pro and HQ series all use this method. 
Actually, the SP-600 uses a variation of it. The dials are metal 
but the vernier dial is driven by a friction clutch on the shaft 
of the tuning knob. The other dial, and the tuning capacitor are 
then driven though a gear reduction system. I have never seen the 
insides of a Comet Pro but think it may have used the same 
arrangement. In any case without the dials the tuning system 
can't work. I suspect making dials may be possible especially 
since I have the hubs but I would like to find original dials or 
at least dials from the series that would fit. I found the 
receiver at a garage sale a fellow was having and didn't look at 
it carefully. Otherwise I would not have bought it. I have not 
make a serious search for dials but maybe now is a good time to 
start.
    BTW, I am not sure but I think the TMC GPR-90 may use a 
similar pinch wheel drive system.

On 3/23/2020 3:07 PM, Bill Cromwell wrote:
> Hi Richard,
>
> Be sure you are sitting down before reading further.
>
>
>
>
>
>
>
>
>
>
>
>
>
> You could temporarily connect digital dial or dials (horrors) 
> and get your receiver checked out. Maybe even use it a little 
> bit that way. When you get the new mechanical dials of course 
> install them and set the radio up to use those. Then use the 
> digital hardware for something else.
>
> If you have no further use for the digital dials (assuming you 
> do this) you can feel free to send them to me for proper 
> disposal <sly grin>. Just a suggestion. I have done such things 
> for temporary and sometimes permanent use. But not to a nice 
> old receiver like these.
>
> 73,
>
> Bill  KU8H
>
>
> On 3/23/20 5:07 PM, Richard Knoppow wrote:
>>     FWIW, the dials on my 129 are not yellowed but the dial 
>> window is. I need to make new windows, does not look 
>> difficult. I just have too much going on to get to it.
>>     Sometime I will find replacement dials for my HQ-120-X The 
>> original dials have delaminated. Not fixable, have to be 
>> replaced. This set was worked over by someone before I got it. 
>> Without tuning dials that work its hard to know if the 
>> receiver works right.
>

-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL