[ARC5] Command Set Commonality

[D C _Mac_ Macdonald]

It's just a guess from this end, but I sort of envision an assembly line at A.R.C. and the others where it was sort of akin to what was likely done at auto plants where the identical chassis rolls down the line and the specific parts for a contract were assembled at different spots on the line.  
 
The appropriate transformers and other common components would be placed at various work stations for installation and specific differing resistors and capacitors installed on a specific wiring line.  Not 100% commonality, but probably better than 70%. 
  
* * * * * * * * * * * 
* 73 - Mac, K2GKK/5 * 
* (Since 30 Nov 53) * 
* k2gkk at hotmail.com * 
* Oklahoma City, OK * 
* USAF & FAA (Ret.) * 
* * * * * * * * * * * 
 
 
> To: arc5 at mailman.qth.net
> Date: Fri, 11 Apr 2014 22:09:55 +0000
> Subject: Re: [ARC5] Command Set Commonality
 
 
 

From: J. Forster
> Sent: ‎Friday‎, ‎April‎ ‎11‎, ‎2014 ‎5‎:‎08‎ ‎PM
> To: Robert Eleazer
> Cc: arc5 mail list
> 
> Has anybody compared the chassis wiring of all the sets in a family to see
> if they are, in fact, identical to the component value level?
> 
> -John
> 
> ===========
> Yes. Used to was be a site where a person did list differences between ARC and SCR, at least, and I think some within each family. Of course that was a couple of computers and a ‘few’ failed drives ago. It eluded me last time I went looking.
> 
> 
> The instruction book for the BC946b that was probably in the box does enumerate the specific differences to the BC 453. Oddly this copy doesn’t have an obvious manual number, was issued January 7 1943.
> 
> 
> Signal Corps manual T. O. 12R2-3SCR274-14 (spare parts list radio set SCR-274-N) does list the variants between types. A convoluted logic system is used where the parts are listed by Item Number. A cross-reference in back does list by schematic symbol leading you back to the front. C4, for example has three listings, one for each Western Electric part number.
> 
> 
> The ARC 5 manual AN 16-30ARC5-2 does list all the variants for R23 thru R27 as well as T15 thru T22.
> 
> 
> > I dug out Gordon's "Command Sets for All Frequencies" article in the Jan
> > 67 issue of CQ to check on commonality for the sets.  Just as I thought,
> > here is what it shows for the C4, the tuning cap.
> >
> > 190-550 and 520-1,500 use the same tuning cap, max 346 pf.
> >
> > 1.5-3.0 and 3-6 use the same tuning cap, max of 147 pf
> >
> > 6-9.1, 9-13.5, and 13.5-20 use the same tuning cap, max of 62 pf.
> >
> > 20-27 uses a max 41 pf tuning cap.
> >
> > So, with the pluggable IF's, pluggable RF's and easily removable BFO coils
> > they could cover all the production models as well as most of the special
> > ones with just 3 tuning caps.   Darned clever!
> >
> > Wayne