[Milsurplus] Navy MBM photo

[Hubert Miller]

I am cleaning out old emails right now. Don't know if I ever answered this. The MBM was built by Jefferson Travis. I think this company had some odd characteristics, but I won't go into all those now.
The manual, for example, says "provision is also made for voice reception". What is this provision? The provision is, you can switch the BFO off.
I actually have two. One I got from Tony Grogan many years back. We speculated about the odd size - large and "flat", or thin - this one had no associated items. Only when I got the second one did
I realize the odd shape was because it, in its waterproof metal case, sits in a suitcase. The only other one I have heard of existing belongs to Steve Bartkowski of Chicagoland. He bought it at the 
Dr. Muchow auction. ( Lesson from the Muchow story: your empire will be meaningless after you pass. )  The good one I have is near complete, many spare parts etc. but someone had already
abstracted the crystals, spare tubes, and the handtools.  I can understand the thinking that putting a storage battery inside the set but I still don't think it a good idea with old lead-acid batteries,
too likely for a serious problem to sneak up on you.  Also per the users, in a third world type underdeveloped country under enemy occupation, maybe a large Western looking, heavy suitcase isn't the
smartest thing to be seen lugging around. Did they remark on this on the "User Feedback Form" ?

IIRC the sample competitive sample BC-654 model submitted by Philco also had a 6 volt storage battery in the power supply. 
I just don't trust the seals on those batteries when the battery is subjected to bumps and inversion. 
-Hue 

-----Original Message-----
From: milsurplus-bounces at mailman.qth.net <milsurplus-bounces at mailman.qth.net> On Behalf Of Mike Morrow
Sent: Wednesday, August 16, 2017 8:32 AM
To: milsurplus at mailman.qth.net
Subject: Re: [Milsurplus] Navy MBM photo

Hue wrote:

> For updating your Navy catalog pages, here is an image of the rarely > 
> encountered Navy type MBM CAPI-43066 transmitter-receiver.
>
> Manufacturer: Jefferson Travis
> Year of production: 1945 only
> Production: at least 157, this unit's serial. 
> Weight: 20 lbs ( trans-rec unit only ) Freq range:  4-7.5, 7.5-14 Mcs.
> Modes: receive A1 A2 A3, transmit A1
> Emission power: 20-12 watt; lower power on crystal harmonic.
> Transmitter, 6V6, 6L6.
>
> Employment: coastwatcher and forward operations in Pacific War theater
> Power: handcranked generator, or internal 6 volt storage battery in 
> Power Supply  unit (not shown ), or external 6 volt battery.
> 
> 4 screw holes at 4 corners receive the fasteners for the waterproof 
> lid. 3 composite units are supplied in luggage-style suitcase:
> radio unit; power-supply with internal battery; handcrank generator.
>
> Right 1/3 of radio pictured is storage area for spare tubes, crystals, 
> headphone, key.

The description in the Navy Type Number Catalog

 http://www.virhistory.com/navy/manuals/nt/NT-900109-3.43.rcvr_xmtr.pdf

differs (and is obviously incorrect) in some interesting details.

CAPI- 43066 MBM
RADIO TRANSMITTER-RECEIVER: 
FREQUENCY RANGE 4·14 MC IN TWO BANDS
(4-7.5, 7,5-14). POWER OUTPUT ON A2 IS
l5-20 WATTS BETWEEN 4-7.5 MC AND 6.5·12 WATTS BETWEEN 7.5-14 MC. RECEIVER OUTPUT IS 5OO MW INTO 600 OHM PHONE.  CONTINUOUS TUNING EMPLOYED FOR RECEPTION AND FlXED FREOUENCY CRYSTAL TUNING IS USED FOR TRANSMISSION. JACK ON PANEL IS PROVIDED FOR PLUGGING IN REMOTE TELEGRAPH KEY.
RECEPTION IS A2 & A3.
01/20/1945 MBM UNIT 1
FEB. 1945

That description indicates NO capability for A1 transmission or reception!  That would have been bizarre, were it correct.  Hue's picture shows a receiver "C.W. ON/OFF" switch and "C.W. PITCH" control.  The type number manual description should have shown exactly what Hue wrote.  The manual for the MBM is NAVSHIPS 900,581.

It would be interesting to have a collection of these late-WWII unusual-purpose small HF sets like the AN/PRC-1, AN/PRC-5, AN/TRC-10...and now the MBM.

Is the set pictured in your collection, Hue?  Very interesting...thanks for showing it.

Mike / KK5F
(Does anyone have any info on the MBN, a.k.a. AN/PRC-7(XN-1)?) ______________________________________________________________
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