[Milsurplus] ATD

[Mike Morrow]

Jay wrote:

> My ATD has the following frequency ranges:540-1500kc,
> 1500-3000kc,and two 3000-9050kc tuning units....
> This one is immaculate ... 

Hi Jay,

I think nearly all surviving ATDs are in never-used condition.  I suspect that precious few ever actually flew.

The 04AUG43 manual for the ATD, NAVAER 08-5Q-39, says in section 1-1-4 that the tuning units that you have are the ones normally supplied with each transmitter.  Those are the ones that are in my ATD too.  The CRR-47202 (200 - 540 kc) and the CRR-47211 (9050 - 15800 kc) tuning units, and the CRR-47206 external antenna tuning unit (200 - 540 kc) are noted with "Information on these units is included in this instruction book in the event that these units are made available to the service at some subsequent date."

My ATD came with the CRR-47206, but not the CRR-47202 that goes with it.  One is of no use without the other, since the CRR-47206 can serve no function for ATD operation with any of the other tuning units.

Mike Hanz has the CRR-47202, and there have been reported sightings of the CRR-47211, which must be the rarest of ATD components.

I am fortunate enough to have new-condition ARB, ZB-3, and LM-20 units to make up a complete installation, including all the control, power, and junction box items.  It's a neat set to look at, even if it never saw significant use.

At least one can probably reasonably assert that the performance and flexibility of this installation would have beat the pants off the GP-* with RU-* installations that were common in early WWII.  Plus. even though the ATD required an external dynamotor that the GP-7 did not, if you include all the tuning units required by the GP and RU, and the RU dynamotor and junction box, the bulk and weight of the ATD with ARB would be considerably less.

Mike responded to my comment about the ATD and ARB being technology matches:

>Could you elaborate a bit on the factors you considered in that
>assessment?  Not saying you're wrong, just curious based on what
>I see in the technology in the two transmitters.  I suppose that if
>you approach it from a mediocrity vs mediocrity standpoint, they
>are indeed appropriate matches.

Hi Mike,

That is exactly my view!  IMO, the ATD and ARB represent good solid 1939/40 technology.  The frequency coverage of the ATD as normally supplied closely matches the ARB.  The RF design, even though the ARB was RCA and the ATD was Bendix, seems comparable.  The mode of control (limited remote capability) is comparable.  It all would seem very comfortable and capable in a pre- or early-WWII USN carrier-based aircraft.

In comparison, the Collins ATC is a tremendous jump in performance, capability, and remote control options.  To pair the ATC with such receivers as the ARB or the C-131/AR-modified R-26/ARC-5 units seems inapproriate, had there any other choice.  The best receivers that the USN had were greatly outclassed by the ATC.

I feel a lot better about the USAAF's AN/ARC-8 matchup of the BC-348 with the improved T-47A/ART-13.  With the O-17/ART-13A, frequency coverage of the transmitter is identical to the receiver.  The BC-348 is a much better receiver than the ARB, though both are RCA designs.  The only thing the ARB had going for it is limited remote control.  I believe that the AN/ARC-8 was the best WWII-era airborne HF set in the world.  (I'm not too wild about the huge CU-32/ART-13A that often went with it, though.)  Some active service USAF utility aircraft still carried the AN/ARC-8 in 1970!  

73,
Mike / KK5F