[ARC5] Nomenclature Taxonomy - AN/ART-13B

Sat Jun 25 17:36:08 EDT 2011

At one time, I had a T-412. It had the CDA-T,the interlock switch,the low frequency extend switch and the later CFI unit.The nomenclature tag was a thin aluminum strip with T-412 stamped on it,painted black with white filled alpha numerics that fit over the center of the original tag which if I remember correctly indicated the unt to originaly be an ATC.It had the fine incremental vernier on the VFO also. In addition the multi meter had been replaced with a new sealed version that had domed glass rather than the flat glass. It had a cal book but I do not know if it was the correct version. This was about 10 years ago and I think I sold it at a MRCG meet. Also, the 811's were the "A" version.Don't know if that was an upgrade or not. The ATC I had way back had plain 811's.
 Jay KE6PPF

-----Original Message-----
From: Mike Morrow <kk5f at earthlink.net>
To: arc5 <arc5 at mailman.qth.net>
Sent: Sat, Jun 25, 2011 1:52 pm
Subject: Re: [ARC5] Nomenclature Taxonomy - AN/ART-13B

Robert wrote:
> ...a photograph of T-412/ART-13B is in T.O. 12R2-2ART13-1 (27AUG52) and
 subsequent revisions through 26SEP68.
Most of my AN/ART-13 library is still packed up, so I referred to T.O. 
2R2-2ART13-1 (15DEC56) and T.O. 12R2-2ART13-2 (30MAR56) at:
 http://bama.edebris.com/manuals/military/an-art13/
The -1 manual there does not have a picture of the T-412, nor any explict
eference to "T-412".  
There is a picture of the T-47A with CDA-T and no EXTENDED LOW FREQUENCY
witch on page 1-2A.  There is text on page 1-1 that defines this as the
N/ART-13B.  Operation between 1670 to 2000 kHz is not possible.  These
ages were revised on 27AUG52 to add these details.  This sets a date of
ot later than 1952 for the first early AN/ART-13B systems.  No new
omenclature was applied.
Page 2-19 was revised on 15DEC56 to address the EXTENDED LOW FREQUENCY
witch and operation from 1670 to 2000 kHz.  This indicates that the full
odification of T-47A plus CDA-T plus EXTENDED LOW FREQUENCY circuitry
C151/second S117) was now available.  This sets a date of not later
han 1956 for the first late AN/ART-13B systems.  New nomenclature
-412/ART-13B was applied.
T.O. 12R2-2ART13-2 (30MAR56) addresses the capabilities of the T-412
y name in detail, including pictures on page 1-2 and 1-4 and the 
chematic on Figure 8-44.  This manual could lead one to conclude
erroneously, I believe) that there never was an AN/ART-13B that
id not have the full CDA-T plus C151/second S117 mods that were
art of the T-412.
I believe that one can best categorize the AN/ART-13B as follows:
Early AN/ART-13B T-47A/ART-13 with CDA-T and *no* EXTENDED LOW FREQUENCY
                circuitry.  There is no installed AN/ART-13B nomenclature.
                The -1 manual revision for this model is dated 27AUG52.
ate  AN/ART-13B T-47A/ART-13 with CDA-T and the EXTENDED LOW FREQUENCY
                circuitry.  New T-412/ART-13B nomenclature is installed.
                The -1 manual revision for this model is dated 15DEC56,
                and the -2 manual revision for this model based on the
                T-47A is dated 30MAR56.
> ...addition of the dynamotor interlock switch ("first S117") to NT-52286
 or T-47ART-13 is Modification M1 (and replacement of  the 8Q-1 CFI with
 8Q-2 is M2).
There's also that T-47A VFO dial B backplate with vernier scale to allow
etting one-tenth increments of the minor dial divisions.  That change
s why the calibration book for T-47A/ART-13 is more than twice as thick
s the books for the ATC or T-47.  The vernier permits setting frequencies
n the T-47A in 1 kHz intervals throughout the entire tuning range.  The
TC and T-47 had books with data at 5 or 10 kHz intervals.
> Final revision of T.O. 12R2-2ART13-2 was 25JUN58...The majority of
 the text implies that if a T-47A went through the 10 to 20 hour 
 conversion process to install a CDA-T, it should have gotten a new
 nameplate and "second S117".
I agree, that's what the -2 manual would imply if one didn't know of
he revision history.  Judging from manual revision dates and the late
T-412" designation, I think that the full T-412 mod dates from the
id-1950s, while the first CDA-T installations date from 1952 or earlier.
It's also interesting that the T-412 mod would sometimes be applied to
ld USN ATC and T-47 units that did not have the upgrades of the T-47A.
his can only be determined by looking at actual units in the field, and
ot from these -1 or -2 Tech Orders which show the T-412 as built from
 T-47A.
And one question remains.  What value was the T-412's capability for
f CDA-T crystal-control in the range of 1670 to 2000 kHz in the mid-
950s?  That would seem well past the era when the USAF (or even USN)
ould have found aircraft operation in that frequency range to be of
nough interest that it was worth the trouble of the modification
equired.
Mike / KK5F
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