[Milsurplus] USN: ARB receiver used with GP-7 transmitter?

[Mike Hanz]

>> But in terms of the best overall, most compact for its capability, 
>> most sophisticated
>> radio, how about the ARC-1 ?
>
> I'm curious about the reliablity of the ARC-1.
> I got mine working years ago, but what a HUGE bunch of "stuff"
> is in that radio.  About two dozen 6AK5s IIRC.  Anyone
> ever heard if it was a maintainance problem?


There is an entire 33 page chapter on ARC-1 maintenance items in the 
Sept 1945 ARMN.  It begins with an extensive list of modifications, some 
of which were aimed at performance improvements or operational mods, but 
there are no failure numbers for those which are maintenance problems, 
unlike the AAF Unsat Reports.  The trouble issues run the gamut, and 
include problems with crystals, insulation, autotune, instability, and 
general mechanical items.  There is a note that says, "Reports from the 
field indicate a high percentage of vacuum tube failures."  There 
follows a general blaming on improper handling of the tubes.  They then 
make an interesting statement: "The filaments of 6AK5 tubes have the 
unusual characteristic of decreasing in resistance with usage.  
Consequently, if these tubes are not replaced in pairs, the tube with 
the most operating time will have lower filament resistance and cause 
excessive filament voltage to appear across the new tube, with 
consequent failure."  Who'd a thunk?

73,
Mike