[Milsurplus] BC-221 Questions

[WA5CAB at cs.com]

John,

I didn't see an answer to any of this.

The manuals do not (at least that I ever saw) explain why the change from 
aluminum to wooden cabinets but given approximately when the first wooden ones 
showed up (1942), I presume it was due to the aluminum shortage.  All BC-221-T* 
through BC-221-T except for some BC-221-Q were supplied in aluminum cabinets.  
All double-letter models except BC-221-AA were supplied in wooden cabinets.  
BC-221-Q and BC-221-AA were supplied in both.

All BC-221-s produced were shipped to use dry batteries.  The RA-133's and 
PP-79/UR are post-war.  The BC-221-B and BC-221-Q have an aluminum battery case 
that comes out to install or change batteries.  The PP-79/UR is the 
replacement for this.  In all other models the batteries are loaded directly into the 
battery compartment and then hooked up.  Wiring harnesses and method of securing 
the batteries into the case vary considerably between the models.  The 
RA-133-(*) is the replacement for all of the models except B and Q.

No BC-221 was produced with a telescoping whip.  Some of the models have a 
binding post on the top of the case and a leaf spring contact to connect to the 
actual instrument when it is plugged into the case.  In the rest the antenna 
push-post is on the front panel of the instrument section.  Some few also have 
a ground post on the front panel.  The double-D  hole on yours is probably 
where the top-mounted binding post was.  One of the photos in TM 11-300 shows a 
metal cabinet model with antenna post on the front panel and with a metal snap 
plug toward the left rear of the top of the cabinet.  My assumption is that 
when they switched over to putting the antenna post on the front panels, they 
had cabinets with the hole already punched, and used them with the plug.  The 
other possibility is that the case and instrument aren't original to each other.

All RA-133's that I have ever seen (I currently have 8 or 9 RA-133-B) have a 
hard-wired line cord with a switch-box mounted in it.  The chassis mounted 
connector and switches on yours must be a modification, but who did it I couldn't 
say.  As it has a properly engraved warning plate, it may have been done on 
an MWO but the earliest listing I have is from 1958 and it doesn't show 
anything.  So I don't know.  Sounds like a worthwhile mod, though.  That power cord 
and switch box are a real pain.

In a message dated 5/6/2007 2:19:04 PM Central Standard Time, jfor at quik.com 
writes: 
> I recently acquired a rather nice BC-221-AK and have a few of questions:
> 
> 1.  What was the usage of the metal v. wooden cases? The other two -AK
> units I have are battery powered and are in wooden cases, but I'm almost
> certain I've seen metal case battery units too.
> 
> 2.  Did the metal case units have a telescoping antenna? Mine has a
> double "D" hole on top toward the rear and left side that looks like it
> might have been intended for an antenna mount. My wood cased units have
> no such hole.
> 
> 3.  The newest unit has what appears to be an original RA-133-B AC PS
> installed. What I find a bit odd is the line cord is not attached and
> does not hang out the back as with many WW II instruments. Instead,
> there is a recessed connector on the left side, similar to those used on
> the older (pre IEC) HP instruments. It's very well done, if it was a
> later mod, in that the the edges of the clearance hole are also black.
> The front panel of the AC PS has two toggle switches and an engraved
> plate warning that the rear door should be left open when operating the
> unit.

> 

Robert Downs - Houston
<http://www.wa5cab.com> (Web Store)
MVPA 9480
<wa5cab at cs.com> (Primary email)
<wa5cab at houston.rr.com> (Backup email)
   
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