[Milsurplus] Re: [ARC5] New addition

David L. Stinson [email protected]
Thu, 08 May 2003 17:03:12 -0500


[email protected] wrote:
> 
> Dave,
>  Thanks for the info.This brings up more questions.
> Were there other AN/ARC-5 receivers so modified or just the R-27?

As far as I have been able to document, 
only the R-26 and R-27 were so modified.  
Somewhere in the deep dark cavern of storage, 
I have a wiring diagram that shows 
an ART-13 wired to an autotune R-26 and an autotune R-27.
Through the junction box, channels 1-2-3-4 on the 
C-87 ART-13 control box were settings 1-2-3-4 on the R-26.  
Channels 5-6-7-8 on the ART-13 were 1-2-3-4 on the R-27.
The third place in the receiver rack held an ARR-2,
and the receiver control head was a C-38/ARC-5.

While I have not information on how widely this system 
was used, I speculate it could not have been in service long.
First, and most telling, is the scarcity of documentation.
Second is the mechanical modification.
While the "Yardly Spottuner" autotune unit itself is very robust, 
the single-turn worm gear on the tuning cap 
may have been mechanically unstable.  
It was installed by removing the old gears,
drilling and mounting a different gear train.
The metal used in AN/ARC-5 receiver caps was designed for
thermal stability and probably would not take extra 
machining very well.
The whole thing looks like it could develop some slop
after a month or three of vibration.
I've uploaded photos of the autotune gear train 
modification at:

http://home.mindspring.com/[email protected]/r27spot2.jpg
http://home.mindspring.com/[email protected]/r27spot3.jpg

That's just my best guess as to why it didn't hang around longer.
Personally, I'd love to wire the whole thing up just to watch
the ART-13 and Spottuners go to town. 

73 Dave S.