Wireless of the Week - week 20

[David Dunlop]

Are there any indications the No. 29 Set was going to be a shared production item, like the 19-Set, or was it intended to stay an RCA Victor Canada product for its planned service life?

David

[David Dunlop]

The reason for my inquiry earlier is a lead I received earlier this week through the local Amateur Radio group about an aerial tuner that turned up in town, made by Canadian Marconi Company. I should be able to pick it up this weekend.

The initial thought was it was likely another Coil, Aerial Tuning No. 2 for the 52-Set, but the general description suggests it is smaller than that and it has two separate aerial connections on the output side, from what I understand.

My next thought was it might be a piece of RCN Wireless gear as CMC was very active in that area, but I am told there is a ‘ZA’ Number on it and that the chassis is secured by a set of circular cams. That got me thinking of the 29-Set, but my assumption has always been that set was solely an RCA Canada project and was issued with a variometer, so would not require an aerial tuner.

Will know more about this thing when I pick it up and get some photos of it.

David

[Bruce Parker (RIP)]

The 29 set had a 'variometer' similar in size to a 19 set one but with a big lobe on the side to house the drive motor. There is also an AERIAL MATCHING UNIT No.C1 in a square case about the size of the 29 set supply unit. Its number is ZA/CAN 9268 CMC 105-969 with no maker specified on the data plate as "RCA VICTOR COMPANY LIMITED' is displayed on other components of the set. Safe to assume it's Marconi however.

Both aerial units are shown on top of the 29 set. Note the 52 set style tuning knobs on the C1 unit.

I have no idea whether it was planned to have Marconi produce sets, a possibility perhaps if the war had gone on longer and thousands of sets might have been required to replace 19 sets. But as it turned out of course nothing came of it.

Originally Posted by David Dunlop

The reason for my inquiry earlier is a lead I received earlier this week through the local Amateur Radio group about an aerial tuner that turned up in town, made by Canadian Marconi Company. I should be able to pick it up this weekend.

The initial thought was it was likely another Coil, Aerial Tuning No. 2 for the 52-Set, but the general description suggests it is smaller than that and it has two separate aerial connections on the output side, from what I understand.

My next thought was it might be a piece of RCN Wireless gear as CMC was very active in that area, but I am told there is a ‘ZA’ Number on it and that the chassis is secured by a set of circular cams. That got me thinking of the 29-Set, but my assumption has always been that set was solely an RCA Canada project and was issued with a variometer, so would not require an aerial tuner.

Will know more about this thing when I pick it up and get some photos of it.

David

[David Dunlop]

Interesting, Bruce, thanks for that. When I get this item home I will post photos of it.

The “105” prefix number block shows up in the 52-Set Parts Lists from CMC for the meters used in the set.

Now my curiosity is peaked regarding why the 29-Set was issued with both a variometer and an aerial matching unit. Technically, they both do the same job, but perhaps a variometer has better efficiency with tuning whip aerials and the CMC Matching Unit was better working with long line horizontal aerials in a Base Station environment.

Do the mysteries ever stop, Bruce???

David

[David Dunlop]

This little gem arrived on my wireless bench last week and I finally had a chance to take a quick look at it. Never knew they existed until this one arrived and I was even more intrigued that it was a Canadian Marconi Product built for an entirely otherwise RCA Victor Canada Wireless Set.

This one was used by somebody who thought removing a ¼-turn fastener and replacing two ceramic aerial terminals with UHF Sockets was a huge improvement. However, internally, it all still appears to be there.

The four screws on the right side of the case are, I suspect, mounting screws that allow the Matching Unit to be secured on top of the 29-Set A-Set Case. One screw is missing, but underneath it and that horrid aluminum paint is very original wartime Semi-gloss Olive Green paint as used by Canadian Marconi.

The screw on the back of the case secures a large guide pin that engages a set of holes in the chassis when it is being removed or returned to the case, to prevent damage to the tuning coils.

It is not until you see the tuning coil arrangement inside the Matching Unit that you realize why RCA called CMC in as a sub-contractor for this part of the 29-Set Project they had undertaken. The tuning coil setup is almost a carbon copy of the PA LOADING circuit Marconi used in the Sender of the 52-Set, and it had proved a very successful design. No need for RCA to have wasted time reinventing the wheel.

Interestingly, when I took my first close look at the Matching Unit, I had to smile when I read the Data Plate. The Serial Number is: C-52.

David