[ARC5] C-38/ARC-5

[WA5CAB at cs.com]

I'll add one further comment as to why blanking covers are sometimes but 
not always missing.  If the various controls on the box needed to be set but 
then covered to keep the aircrew from fiddling with them, the tech who set or 
checked them could probably be depended upon to replace them after making 
the check or setting.  But if the box needed to fly with a control 
accessible, unlike some other examples (BC-312/342 cabinet and FT-237 Mount come to 
mind), there isn't a parking or storage spot for the covers.  So when they 
were removed from the box, they were removed from the aircraft.  And most 
likely ended up in a junk drawer in the AT shack.  Where they sat until the Field 
Day preceding the next Zone Inspection or Admiral's visit.  At which point, 
not having any officially sanctioned place to live, they were deep sixed.

In a message dated 10/19/2009 6:05:54 PM Central Daylight Time, 
aaf-radio-1 at aafradio.org writes: 
> >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
> 

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480