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

[Thomas Adams]

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. I have never met a veteran
>>WW2
>>airborne radio operator to ask these questions, I wonder how many are
>>still left?...  :(
>>
>>      Bruce Gentry   KA2IVY
>>
>>On 1/7/14 7:55 AM, David Stinson wrote:
>>>LMs that I've seen usually need a lot of the oil-filled caps
>>>replaced.
>>>If you have one, like a bypass, on any of the voltage busses
>>>and it's leaking, it can pull the oscillator regardless of the power
>>>supply regulation.
>>>Some of them a real bear to replace.
>>>
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