[ARC5] Strange "ARC-5" 6743 Tuning Knob

[Michael Hanz]

The only things that are apparent are that it's an SCR-274N contract 
item, the drive shaft has been removed and riveted back on at some 
point, and the original black Bakelite spinner knob appears to have been 
updated with a slightly larger diameter replacement.  As to the tapped 
holes, I have no idea.  Pure speculation, but it could have been to 
fasten a larger knob (like the aluminum disk from an RU or SCR-183/283 
local tuning knob) to the top of the 6743 to make tuning easier (after 
removing the original 6743 spinner knob and its axle - perhaps it was 
frozen or split from aluminum corrosion of the axle, as many of them 
are).  The seller may have decided it was worth more with a new aluminum 
shaft and look-alike spinner - they are not hard to make and install.  
The dimensions are shown at the very bottom of the page at 
http://aafradio.org/garajmahal/flex_drive_cables.html

Todd's understanding of the knob's use seems plausible over time, 
although the earliest 6743s on the RAT were delivered as part of _each_ 
receiver to be used when remote control was not considered necessary.  I 
have to admit that they are very tiresome to use in a band scanning mode.

  - Mike  KC4TOS

On 2/2/2018 11:16 AM, Todd, KA1KAQ wrote:
> Very interesting. Looks to be tapped for some other means of cranking, 
> though automated tuning would seem out due to the coarse nature in 
> which these things are built - too much 'slop'. My understanding is 
> that the local tuning knobs were built with one purpose in mind: 
> servicing. This is a job for.....the Hanz!  If anyone can trace its 
> origins and purpose, he can.  Of course, Gordon may have several in a 
> drawer at home and know exactly where they were used and why, too.
>
> ~ Todd/KAQ
>
> On Fri, Feb 2, 2018 at 9:46 AM, David Stinson <arc5 at ix.netcom.com 
> <mailto:arc5 at ix.netcom.com>> wrote:
>
>     https://www.ebay.com/itm/112789379793
>     <https://www.ebay.com/itm/112789379793>
>     Comments on this tuning knob?
>
>     73 OM DE Dave AB5S
>

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