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

[Mike Morrow]

Michael wrote:

> Did the CDA-T replace the VFO or was it used in addition to it?

One can select frequency control using the crystal oscillators in the
CDA-T, or frequency control using the T-47A's original VFO (Dial B).
This selection was made with the VFO-XTAL switch on the CDA-T front panel.

The CDA-T has two separate crystal oscillator systems, both of which are in
effect when the VFO-XTAL switch is in XTAL:

"LF" Oscillator (1625) that can have four selectable crystals in place.
(LF in a misnomer...the CDA-T low operating limit is MF, 300 kHz.)
Allowable frequencies of operation are 300 to 500 kHz.

"HF" Oscillator (6AG5) that has a bank (A) of ten crystals each individually
selected with the T-47A channel switch.  In addition, a parallel bank (B)
of ten more crystals may be selected.  There is an A-B select switch on the
CDA-T front panel (and on some modified remote control boxes).  For any given
channel, the bank A crystal and the bank B crystal share the same tuning setup
that is stored in the autotune system.  Thus, the bank A and bank B crystal
frequencies must be within 3 percent of each other.  Allowable frequencies
of operation are 2000 to 18100 kHz (1670 to 18100 kHz if the transmitter is
a T-412/ART-13B, using the EXTENDED LOW FREQUENCY switch that was added).

> If the latter, how was it controlled?

If the VFO-XTAL switch is in VFO, everything works like a normal T-47A without
any LF/MF (O-17) oscillator installed.

If the VFO-XTAL switch on the CDA-T is in XTAL:
(1)  Select L.FREQ on the T-47A channel switch, select one of the four LF 
     oscillator crystals, put dial A on position 13 to select LF oscillator
     output.  Then proceed as normal to tune up the L.FREQ channel.
(2)  Select channel 1 though 10 on the T-47A channel switch, select bank A
     or B crystal on the CDA-T, proceed with normal tune up (VFO dial B is
     non-functional).

Presumably, the CDA-T would almost always be the normal frequency control,
without attempts to operate some channels on the VFO and some on the CDA-T.
That would be possible with careful setup and local control of the VFO-XTAL
switch, but there's a lot more room for error that way.

> ...what receiver was used with these transmitters?

Assuming that it was used by the USAF, it would have been in an otherwise
standard AN/ARC-8 set, and the receiver would have been the AN/ARR-11, a.k.a
the BC-348-*.

I sometimes wonder if any ever showed up in U.S. Navy use.  It's possible, I
guess.  In that case, it would have been part of the AN/ARC-25 set, and the
receiver would have been a R-105(*)/ARR-15.

(PLEASE...anyone...if you have any evidence for USN use of the AN/ART-13B
I'd love to know about it.)

> ...was this the *functional* predecessor to the Collins 18S-1?

Well, that's a receiver-transmitter, and in toto quite different other than
using some AN/ART-13 type components in the transmitter section.  So I wouldn't
say so, at least as far as the CDA-T is concerned, but I suppose it can be argued.
The 18S-4 is also an early 1950s set, adopted eventually in military service as the
RT-380/AR, part of the AN/ARC-59.  I don't how extensive the use of the AN/ARC-59
was, compared to the use of the AN/ARC-8, AN/ARC-21, and 618S-1 by the USAF, or
the use of the AN/ARC-25 and AN/ARC-38 by the USN during the 1950s.

Mike / KK5F