[ARC5] Navy LM Use

[Sandy Blaize]

Could not agree more.  There are instances where you don't need a BBC-221 or 
the LM.  The ART-13 (late model) was a prime example.  My personal 
experience with sets later than the ART-13 is NIL, so can't argue about ANY 
of the later stuff.  I don't remember seeing any of the Navy transmitters 
that were capable of being reset to a precise frequency on HF, but then my 
association with Navy gear wasn't really "personal"....I have seen it but 
never operated it.
The BC-375 which was on all the bombers for a Liaison set was a typical 
1930's "MOPA" setup.  You set the oscillator frequency, then tune up the 
whole rig.  Then RECHECK the frequency again, because the interaction of the 
PA would "pull" the oscillator stage someplace else.  Sometimes just a "tad" 
sometimes a whole lot!  If'n you don't have a BC-221 you are screwed.  I 
don't see in many instances in battle how they were ever set on exactly the 
same frequency.  There are other voltages that basic HF set were setup for 
(BC-191) and it was a Basic Component of several "SCR" installations fixed, 
portable and mobile devised by the Signal Corps.  A lot of the "newbies" of 
today would have a terrible time getting one tuned up right I am sure.  They 
are both usable and FUN when you get the hang of some of the older gear.  Of 
course "quartz crystals" were a more "modern way" of getting on the right 
channel without the fuss of a frequency meter.

73 to all,

Sandy W5TVW

-----Original Message----- 
From: Mike Morrow
Sent: Wednesday, May 22, 2013 1:04 PM
To: arc5 at mailman.qth.net
Subject: Re: [ARC5] Navy LM Use

> ...bring up the question again of why the USN included an LM
> frequency meter with essentially every large aircraft radio
> installation.

I don't believe this is a valid observation.  No WWII-vintage
USN transmitter or receiver system had the capability to be
set on frequency accurately with the indications on the radio
set itself until the ATC.  Most liaison transmitting systems
of the era have a CFI input terminal that goes to the LM-*,
the LM was integral to frequency adjustment.

An accurate assessment of USN installations would simply be
that *ALL* aircraft with a radio operator (and liaison system)
always carried the LM-*.  Aircraft without a radio operator
did not.  The only exception might be the large single-engine
aircraft like the SBD, TBD, and the like, which had radio
operator/gunners.  I don't know if an LM was always standard
in such aircraft.

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