[Milsurplus] Fwd: Re: LM/BC-221 stability

[Mike Hanz]

All good thoughts.  Here are some more, for what they're worth:

USAAF aircraft usually had a designated place for the BC-221 on board.  
A quick perusal of the maintenance manuals shows their normal locations 
and functional use in the aircraft.  For example, the B-25 location was 
"on a shelf on the right-hand side of the radio operator's compartment, 
at the rear entrance of the bomb bay passageway."  They do *not* 
indicate typical frequency of use during a mission, or if it is 
typically never used.  I suspect Mac is quite right, though the knobs 
are not too much different than the BC-348 from an ergonomic 
standpoint.  Now, take a look at some of the Navy radios like the ATD if 
you want to contemplate problematic flight adjustments at high 
altitudes....:-)

In contrast, Navy usage of a frequency meter was clearly different.  In 
any of the larger aircraft there was a prominent place in the radio 
compartment that was handy to the operator - see the bottom of 
http://aafradio.org/flightdeck/RAX-1.htm as an example.  Just 
speculating, but it may have been driven by the significantly larger 
area the Navy flew over beginning back in the 1930s, and the need to 
change frequencies more often as a result.

The creation of the TS-164/AR "permanent" version of the BC-221 
(http://aafradio.org/docs/TS-164.html ) may have been due to a shift in 
the global operations of the USAAF in the last half of the war, and 
along with it, the increased frequency of independent patrol flying that 
more resembled Navy operational practice.  The contract dates I've seen 
of a number of them are usually in the 1944 and 1945 time frame.  
Hamfests around Washington DC used to yield 2-3 every summer, and a 
friend of mine found a barn with stacks of them - in Ohio, IIRC.  Sadly, 
the barn collapsed soon after he found the stash...:'(   Most of the 
hamfest models I've seen had been modified by hams, with power supplies 
added to the rear.

- Mike  KC4TOS

On 1/9/2014 3:19 AM, Thomas Adams wrote:
> Again, a personal two cents worth.
>
> I agree...  pre-spot the BC-375 before the mission takes off. And yes, 
> about the only time they'd
> need the relatively high power of a BC-375 is on the post strike 
> report back to base.
>
> Naturally, with vibration an temp change, the rig is gonna drift some, 
> but bear in mind that
> BC-348s and BC-314s used to receive the signal have an IF bandpass 
> like a barn door...  so no
> problem!
>
> There WAS an airborne version of the BC-221, powered off of the BC-348 
> dynamotor...  but I
> think that was an innovation for the B-29 and later. It makes sense; 
> as pointed out, using a
> BC-221 in the somewhat rugged environment of a B-17, B-24, or a B-25 
> would be a challenge.
> But the B-29 was another animal altogether; pressurized and heated.
>
> The airborne version of the BC-221 is relatively rare; I've only seen 
> one. However, the Navy must
> have had a different philosophy than the Army Air Corps; the LM meters 
> are quite often seen
> with a shock mount; I've never seen one WITHOUT the meter half of the 
> shock mount there.
>
> Mr. T.  W9LBB
>
> At 00:50 09-01-14, mac wrote:
>> Only WW2 airborne radio office I ever had a chance to talk to flew in
>> B-25s and he reported that he NEVER used the BC-375, only the command
>> radios.  Have also heard reports that in the B-17s and B-24s the -375s
>> were normally only used for a short , one time "mission completed"
>> report after the bombs had been dropped.  I suspect tuning and
>> adjustment of the radios was done almost exclusively on the ground
>> before the mission and only rarely in the air after takeoff. (Also,
>> imagine trying to use a BC-221 at 30K ft. with heavy gloves on.)  One
>> exception might be if an aircraft was diverted to a rescue or other
>> maritime mission which would require re-tuning down in the MF range.
>>
>> My 2-cents worth anyway.....
>>
>> Dennis D.  W7QHO
>> Glendale, CA
>>
>> ************
>> On Jan 8, 2014, at 6:18 PM, Bruce Gentry wrote:
>>
>>>
>>>
>>> -------- Original Message --------
>>> Subject:        Re: [Milsurplus] LM/BC-221 stability
>>> Date:   Tue, 07 Jan 2014 08:43:05 -0500
>>> From:   Bruce Gentry <ka2ivy at verizon.net>
>>> To:     David Stinson <arc5 at ix.netcom.com>
>>>
>>> This discussion of BC-221s has caused a question to arise regarding
>>> their use on bombers. Did each radio operator set up the BC-375 with
>>> their own BC-221, or did one plane do so and all the others "spot"
>>> him?  How about the drift of BC-375s, did the home base send a short
>>> message frequently so the radio operator could zero beat it and be on
>>> exact frequency for their reply?  Did each bomber make a report, or
>>> did
>>> one or two report for them all?   What happened if the mission
>>> required
>>> total radio silence both ways until it was time to report results.
>>> Was
>>> the BC-221 and BC-375 accurate enough to be on frequency? This
>>> would be
>>> far more important for CW than AM,  it is unlikely the inaccuracy
>>> would
>>> be a problem on AM for a broad receiver.