[ARC5] identification of Command Set sources and distribution

[WA5CAB at cs.com]

Henry,

Early production SCR-274-N receivers and transmitters were all black.  That 
would be the -A models.  Late production are unfinished (plain aluminum 
finish).  That would be the -B models.  But early -B models were also black.  
If I had just written "BC-455-B", and hadn't specified color, the assumption 
would be it was aluminum finish.  Which is why I wrote "black BC-455-B".  
They are, relatively speaking, uncommon.

On ID'ing your two "German" receivers, first check is to ID the 2nd IF 
tube.  If 12SF7, then the receivers are AN/ARC-5.  Which one specifically you 
can determine from the frequency coverage of course.  If not ARC-5, second 
check is to count the number of terminals on the audio output transformers.  If 
there are six (6), then the receivers were originally -B model SCR-274-N.  
If there are five (5), measure the resistance of the secondary winding.  If 
between 292 and 370 ohms, then -A model SCR-274-N.  If around 21 ohms +/- 
then ARA.

There are other indicators as well.

Robert

In a message dated 9/27/2010 1:54:55 PM Central Daylight Time, me
ils at get2net.dk writes: 
> My two "German" Command receivers are compatible with my twin-receiver
> rack that accommodates my two BC-453-B's, made by respectively,
> Western Electric and Colonial Corp.
> And as I assume most if not everyone on this thread knows,
> the rack is also compatible with my R23/ARC-5 and R27/ARC5's.
> I was hoping that the two types were not compatible, to help me narrow
> down the in identifying the German units -- but that's no real problem
> because I can compare them with my BC-453-B's  and my
> R23 &R27/ARC-5 units.
> 
> I also have serveral Command set transmitters, most in original form.
> Several of my Command sets were obtained when I lived in NYC
> so I doubt their contract no.s are of any particular interest.
> 
> Mike-WA5CAB, you mention a black BC-455-B (Sure you're not confusing it 
> with 
> an R-25/ARC-5? -- just kidding!)
> It seems that after all 1964 is a gap in my CQ collection, but I do have a 
> 
> photocopy of
> Gordon Elliot's 'The Command Set Story' article.
> 
> (My CQ articles are in Nov. 60, p. 71, on the TCS transmitter and in the 
> DX 
> section of  March 71,
> pp 95-6 - about ham radio in Denmark).
> 
> Hope I haven't made any major booboo's this time around ;0)
> 
> Henry, Cph.
> 
> 

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