[ARC5] C-38/ARC-5

[Mike Hanz]

Mike Morrow wrote:
> Jay wrote:
>
>   
>> Thanks Mike for all the good info.Also on the auction block is a 
>> C-38A/ARC-5.This one has no covers over REC. B switch,associated SET 
>> FOR MAXIMUM TOLERABLE NOISE control, or the MIC selector switch as does 
>> my C-38/ARC-5 box here.Are these covers the difference between a -38 
>> and a -38A ?
>>     
> No, there's some very minor difference in the audio circuit.  Mike Hanz
> sent me a description of the difference between the C-38 and the C-38A,
> but I have it archived on another computer.  (Mike...do you care to post
> the info again?)
>   

Not a huge change.  Starting with serial number 4501 (CBY), a shorting 
jumper was added across R1004, R-1014 (620 ohms) was added in parallel 
with R-1002, and R1008 was was changed from 2000 to 620 ohms.  All CCT 
units have these changes, according to the ARMN, so Jay should be good.

The C-38/C-38A is sort of a curious device, since it's only value-added 
was integration of the R-4/ARR-2 control portion with a master audio bus 
control.  The rest is just an audio mixing box, and as a result it was 
eventually replaced by a series of interphone mixer boxes, starting with 
the C-126/AR and C-137/AR (http://aafradio.org/flightdeck/box.htm ) and 
the functions eventually absorbed into the master interphone control 
boxes like the C-380/AIC-5 ( bottom of 
http://aafradio.org/flightdeck/Interphone_systems.html ) and its successors.

73,
Mike