[Milsurplus] BC-375: Unusual TU-10 Tuning Unit
Thomas Adams
quixote2 at ix.netcom.com
Sun May 21 23:22:33 EDT 2006
Howdy.
When digging out the stashed away tuning units for my
newly acquired BC-375, I discovered that I have a VERY
odd one that isn't covered in the BC-375E manual.
I have a TU-10A (coverage = 10,000-12,500 KHz). It sort
of stands out immediately because it has, on it's front
panel, two spring loaded binding posts which are, I can
only assume, going to an antenna WITHOUT going thru the
big antenna matching network included in the transmitter;
ie, it appears they go directly to the output link coil
for the PA!
The backs of the binding posts include couplers that allow
the output link to simultaneously feed the transmitter's
antenna tuning circuits... so it's possible to either go
thru the matching network or couple the link directly to
an antenna at the operator's choice.
The binding posts DO appear to have been installed at the
factory; this isn't a field modification. They're not
labeled. However, they're rather badly placed; when you tune
the PA plate variable cap, your fingers get AWFUL close to
them, risking an RF burn if you operate it with a hand not
encased in a leather flying glove.
The nomenclature plate on the TU gives a construction date
of 1936... quite a bit earlier than your common garden
variety BC-375 tuning unit.
What am I dealing with here? Is this perhaps a BC-191 TU?
If not, did aircraft installations commonly use a seperate
antenna for that tuning range?
Anything that anybody here knows about this oddball would be
of assistance re. what's going on here.
73's,
Tom, W9LBB
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