[Milsurplus] BC-375: Unusual TU-10 Tuning Unit

[Thomas Adams]

Hello Robert!

Thanks for the information...   ditto the other responses to my question.

Re. this TU...   I don't  think I've ever seen a nomenclature plate this
specific. The EXACT contract date is given; "DATE 5-18-36" .

For folks who keep track of serial numbers re. dates...  the S/N on this
one is #449.

A correction re. my previous post...   the binding posts ARE labeled; "1" 
and "2"!!! I just took a closer look; thought the 1 was a scratch in the
paint!  <<smile>>


73's,

Mr. T., W9LBB 


At 11:30 AM 5/22/2006 EDT, you wrote:
>Tom,
> 
>    I have a TU-5-B made on a low number NY-41 Order, which means no later
>than 30 June 1941.
> 
>  I'm supposed to have a BC-375-D manual but have apparently mis-filed it.
> 
>   They are connected to the tapped secondary of the power amplifier tank
>circuit through control ANT. COUPLING SWITCH D.".
> 
> In a message dated 5/21/2006 10:22:59 PM Central Daylight Time,
>quixote2 at ix.netcom.com writes: 
> 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
>  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
>  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
> Robert Downs - Houston
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