19-Set Vario/Aerial Base Mounting Plate

[David Dunlop]

My friend here in town has checked his set and the aerial base is apparently an 'AERIALBASE No 10 Mk II' with ZA14172 and PC825740 also cast into the rubber. The Control Unit is a No.2 Mk II, which if the correct model, also raises the question of how the unused 12-pin socket was protected from the elements. Were protective caps ever issued for these things?

Also looks like four cheesehead screws hold the mounting plate in place as Chris noted.

David

[Chris Suslowicz]

Originally Posted by David Dunlop

My friend here in town has checked his set and the aerial base is apparently an 'AERIALBASE No 10 Mk II' with ZA14172 and PC825740 also cast into the rubber. The Control Unit is a No.2 Mk II, which if the correct model, also raises the question of how the unused 12-pin socket was protected from the elements. Were protective caps ever issued for these things?

Also looks like four cheesehead screws hold the mounting plate in place as Chris noted.

David

Aerial Base No.10 replaced Aerial Base No.8, and had a metal clamp (two strips riveted together with a wingnut, as used on Aerial Base No.11) instead of the spring wire clip of the No.8. Aerial Base No. 10 Mk.II replaced that clamp with a one-piece wrap-around clamp with wingnut one side (to operate the clamp) and knurled nut the other side to allow an aerial feeder to be connected. The rubber insulator was also changed slightly: the Mk.1 met the steel mounting flange at a sharp angle, and tended to separate, so the Mk.II had a slight concave curve at the boundary to give a better bond between the steel and rubber.

The Control Unit No.2 would have a 12-way cable fitted in the spare socket. This would be fixed to the vehicle (in e.g. a jeep) and run to a permanently fitted Control Unit No.1 in the front of the vehicle. If the set was being used dismounted from the vehicle, it would be under cover (building or tent), so there would be no need to protect the spare socket.

I think the securing screws for the plate are standard 2BA x 1/2-in cheesehead. (Hex bolts were also used as it's hard to get at the ones under the variometer.)

Chris.

(On that note, it's heading for Oh God o'clock here (0045Z) and I'm going to bed. Goodnight.)

:-)>

[Patrick Johnson]

Hi David,
As the owner of the WS19 set pictured above I can shed some light into the plate's identification and how it is fastened to the Transceiver case. A look on the underside of this plate yields the following original description spray-painted on the right side of the plate: Plates, Mounting No. 1 - ZA-10465.
On the top of the Transceiver case are two rectangular registering plates, each comprising two sets of three holes in a V-shaped configuration. Correspondingly, on the underside of the mounting plate are four "saddles", each holding a small threaded bolt with a clever retaining ring which keeps it in place. On this example only three of the original four mounting bolts remain, so at some point one of the bolts was removed and never replaced. The saddles with their extended bolt heads register perfectly with the middle tapped hole in each of the four mounting hole groupings. It's a simple operation to hand tighten the bolts into the top of the case, until the final couple of turns when a wrench would be used to firmly tighten down the plate to the case. I've also photographed the monogram found on the bolt heads holding the aerial and Variometer in place, as well as the small round black ink stamp of unknown significance. To definitively answer your question David, yes, the right 1/3 of the plate is truly cantilevered beyond the registering plates of the case.
Hope this helps,
Patrick

[Chris Suslowicz]

Ah, excellent! My plate is almost certainly a later version than that (or has been given an all-over repaint post-WW2). It's also missing all of the bolts, but now I know what they look like I can make some up to suit. The missing bolt on your plate may be deliberate - the one under the front of the variometer is difficult to access so may have been omitted (or they assembled the variometer to the plate and found they could not then fit the bolt).

The circular stamp is almost certainly an inspection mark.

Thanks for posting the photographs, very useful.

Chris.

[David Dunlop]

Thanks for posting your photos, Patrick. They indeed answer a huge number of questions about what we now know are Plates, Mounting No. 1, complete with their ZA-Number.

Chris is correct, the small black circular stamp is an inspection mark from whatever factory made these plates. It should say INSPEC MECH around the rim with the number of the actual inspector in the middle. For certain, RCA did not make these plates as their stamp would also have been present - another black ring with RCA in the middle.

Interesting that the underside of the plate is unfinished, other than the either cadmium or zinc plating. I think I spotted a bit of paint overspray on one of the underside edges and am wondering now if the normal state of these plates was actually plain plated metal, with no factory painting, like the Seating Plates No. 4 used to mount the variometer on the Truck and Ground Installation Carriers. I have a call into my friend here in Winnipeg to check his plate in that regard.

Nice shot of the connector between the variometer and aerial base as well. Whenever you have a chance, can you take some measurements from it for me? The diameter of the cable itself and the length end to end where it stops inside the end connectors. Interesting that two different end connectors are shown. I suspect the one at the aerial base end was a replacement at some point. It is a solder type and would take a bit more work to install. The one at the vario end is a crimp on style and, I think, another Ross-Courtney product. Probably the original factory fitting. At the aerial end, is that a small yellow collar hiding up by the end connector. Sometimes these have a part number ID in black letters printed on them but on smaller cables the ID information is usually not applied.

I was expecting the usual three BSF countersunk slot head screws to mount the variometer assembly. Interesting they went with the BSF hex head bolts, and I notice they are all the thinner hex head type, not the more common fat head jobs.

Are the four retained fasteners that mount the plate assembly to the top of the transceiver slotted cheese head screws, or also hex head bolts?

As I said, Patrick, a whack of info in your photos! Thanks again for posting.

Now we need to get the title of this thread changed to read:

Plates, Mounting No. 1


David

[David Dunlop]

Just got a response back from my friend here in Winnipeg about his Plates, Mounting No.1 and he confirms an unpainted underside. The top of his has been painted flat black by hand at some time. One can make out some brush marks on the larger surfaces apparently and some drips down the edge on one side, so his might have been all plated metal originally. Chips in the paint show plated metal beneath and no sign of a primer.

Thin head hex bolts used for all three items attached to the plate.

Chris: I have seen those little spring retainers on the four hex bolts BA No.2 that bolt the assembly to the top of the transceiver used with some other piece of equipment at one time, but I am beggared if I can remember what piece of equipment! Whenever you get around to tracking your Plates, Mounting No.1 down, can you spec out these four BA No.2 hex bolts for us? Total shaft length, length of thread and how far from the head the retaining clip slot has been cut?

When I think of it, it makes sense they used thin head hex bolts to mount this Plates assembly. Not enough room around the variometer to get at cheese head slotted screw with a screw driver. Would think one has to be careful tightening them, however. With the shaft cut for the retaining clips I could see the bolts shearing easily at that point if you had some knuckle dragger working the spanner!

David

[Chris Suslowicz]

Originally Posted by David Dunlop

Just got a response back from my friend here in Winnipeg about his Plates, Mounting No.1 and he confirms an unpainted underside. The top of his has been painted flat black by hand at some time. One can make out some brush marks on the larger surfaces apparently and some drips down the edge on one side, so his might have been all plated metal originally. Chips in the paint show plated metal beneath and no sign of a primer.

Thin head hex bolts used for all three items attached to the plate.

Chris: I have seen those little spring retainers on the four hex bolts BA No.2 that bolt the assembly to the top of the transceiver used with some other piece of equipment at one time, but I am beggared if I can remember what piece of equipment! Whenever you get around to tracking your Plates, Mounting No.1 down, can you spec out these four BA No.2 hex bolts for us? Total shaft length, length of thread and how far from the head the retaining clip slot has been cut?

When I think of it, it makes sense they used thin head hex bolts to mount this Plates assembly. Not enough room around the variometer to get at cheese head slotted screw with a screw driver. Would think one has to be careful tightening them, however. With the shaft cut for the retaining clips I could see the bolts shearing easily at that point if you had some knuckle dragger working the spanner!

David

I suspect the retaining clips are the same as those used on the WS19 control units, and possibly the supply unit retaining screw. That may be a suitable source of patterns for the clip, although they all use "fillister head" screws.

My plate came as a bare plate, no screws or clips.

All the early/unissued mounting hardware that I've seen has been 'bright', i.e. unpainted (plated) steel. I suspect it was painted to suit the application prior to installation. The post-WW2 hardware seems to have been supplied in green finish.

I'm somewhat surprised that lock washers are not fitted to the various bolts.

(My suggestion of "Plate & Bracket Assy No.1" came from Wireless for the Warrior Volume 2, where it is used throughout. It may be a mistaken designation for the bracket used for the "Condenser X5, 5kV" used with the RF Amplifier No.2, but I'm not sure of this. I wish we had more "Comm. Inst." EMERs (i.e. more than zero) available for the WW2 kit.)

Chris.
(Still gap-filling the "Satchel, Signals" collection - I currently have numbers 1, 2, 3, either 4 or 5, 6, 7, 8, 10 and 12! I have no idea what went in No.8, possibly a test meter of some sort. There are several variations of the No.1 and at least a couple of the No.2 satchel.)

Chris.