C-42 Set Dummy Load
 

I think this item may also be referred to as "Simulator Aerial Tuning Unit No. 1" as the ZA 46625 Number appears to refer to both nomenclatures.

My Radio Station C42 Instructional (ex Cdn Army) has been missing this piece since I purchased it some 20 years ago. Never thought much about it, but the four empty holes on the rack are starting to call to me now.

Based on the photos in the Operators Handbook, the C42 Dummy Load looks externally to be identical to the standard Aerial Tuning Unit No. 6, so I am assuming the differences are all internal.

If the dummy load cannot be found, can anyone advise what I would need to do with a standard ATU No. 6 to convert it, or at least make it look like a Dummy Load?

David

I believe I recall that the item you're looking for is/was painted gloss grey.

In our Signal Corps unit we had a full classroom set up with C42s for instructional purposes. I can't recall us ever having these items, nor can I recall how the dummy load was set up.

I too searched for ~20 years for one and came to the conclusion that they were unobtanium.

I did actually see one last year in an SK auction.

(I don't know who bought it, though.)

They are indeed painted grey.

Chris.

According to the Installation Instructions (photo attached), the C42 Aerial Simulator (Dummy Load) uses special mounting hardware as highlighted in Item 3 of the photo. Four hardware sets are required and they appear to be made up of a two part standoff insulator/spacer with a screw or bolt passing through it. The only reference I can find in the instructions to these parts are the ZA Numbers for the two pieces of the insulator/standoff: ZA47035 and ZA47036.

Can anyone identify what these two items actually are and the size of the bolts needed to secure them?

Secondly, does anyone know a source of supply for these standoff/insulators?

Thanks,


David

Unobtanium
 

Jon, I specialize in unobtainium. Pm me if you need a C42 Aerial Simulator: NOS of course! .... Brian

OK. So following a large pail of tea to start the day, I had another read of the C42 manual and found the following references to the mounting hardware for the Aerial Simulator (Dummy Load).

ZA 47035 (5340-99-949-1084) Bushing, rubber, 0.3280 in id x 1/2 in od x 1-13/32 in lg

ZA 47036 (5340-99-949-1043) Bushing, rubber, 1/2 in dia hole x 3/4 in sq body x 1/4 in o/a lg

A process of elimination leads to the hardware used possibly being: Screw, cap, hex hd, low carbon, st. cad. or zn pl, 1/4-20UNC-2A x 2, with corresponding flat washers (8) and nuts (4).

Seems there is a need to make sure the body of the Aerial Simulator is not in contact with the main C42 set metal mounts. Impact shock or electrical? Hhmmm. The manual does warn never to use the set on high power when operating through the Aerial Simulator.

Wonder if there is any chance those bushings are still in the system.

David

Thanks to the eagle eyes of Chris S in the UK, I now have a complete set of the elusive bushings to mount my C42 Aerial Sim to the Rack, Electrical equipment on the Radio Station C42 Instructional. Incidentally, though not mentioned at all in the assembly instructions, these same bushings and hardware are needed to mount the actual Aerial Tuning Unit No. 6 to it's Support box.

The attached pictures show:

- The actual bushings: ZA 47035, ZA 47036 and combined as in assembly.

- My C42 Set, now complete with Sim.

Mounting the bushings is quite simple. The trick is having the hardware ready to install. ZA 47035 is inserted through the front of the mounting hole in the rear plate of the ATU and ZA 47036 can then be pressed over it and squared off nicely to the ATU plate. They will stay in place while you hold the ATU to either the Support or Rack and pass the bolt with flat washer attached, through the assembly. Slide the lock washer on the end of the bolt and start the hex nut in place. Repeat for the remaining three hardware sets.

Once you start tightening down the hardware, do so for each set until you feel the ZA 47035 bushing bulging out behind the flat washer. Then back off the nut until the bushing just returns to it's original taper. When all are done, you are good to go.

Looking at the design of these things I now suspect these bushings are intended to dampen out any shocks that would likely damage the meter assembly of either the ATU or Sim.

Hope this helps, and thanks again Chris! :salute:

David

Been a while since I visited with my C42 Set, so thought I would update a few small projects related to the Aerial Simulator and the ATU.

The Eagle Eyes among you will notice a few changes in the first photo from the last photos posted here.

After mounting the Aerial Simulator, I was able to install the Instructional Aerial, used in the classroom environment.

In addition to the Aerial Simulator I purchased from Brian Asbury, Brian was also able to provide me with an NOS pigtail that connects the ATU to the Aerial Base. The rubber on the original one had totally perished over the years. Brian had also taken the time to send me some photos of a complete NOS ATU kit from his files, highlighting the Grounding Post assembly. From those photos, I was able to locate the correct hardware, and with some perfect donations from my Wife Debbie's jewellery crafting supplies, fabricate the missing post.

I also decided that the wartime, adjustable A-Set adapter from one of my 19-Sets, made more sense being part of the C-42 Set, so have relocated it there. Easy enough to move back to the 19-Set if I need to, in any event.

David