Wireless Set No. 52 Canadian - Project

[David Dunlop]

This test meter arrived in the mail yesterday afternoon.

In the original Issue 1 of the F524 2nd to 4th Echelon Work Manual for the Wireless Set No. 52, when doing calibration/alignment work on the Sender, one had to construct a Dummy Load from a number of switches, capacitors, resistors and an ammeter to tune against. However, in the 18 January 1961 Revision 2 of F524, this Marconi Instruments Ltd TF957/1 Wattmeter was available to do the work for the Low Power output work on the Sender. It was simply connected between the Aerial and Ground, along with a 120 V, 150 W Light Bulb and away you went with your test work.

At the same time I had discovered this information, this meter popped up for sale on eBay out of Alberta. Quite a surprise when it arrived. I was expecting something in size comparable to a typical RCA, or Simpson, Multimeter of similar vintage, but this 15 lb, 12 inch high by 10 inch wide by 8.5 inch deep beastie showed up instead. Quite a size for a passive piece of test gear.

The meter is a Marconi Instruments Ltd, England product from 1957 and the TF957/1 was the export version of the TF957 for the North American Market. The main differences are the use of BNC terminals for the 1-Watt and 25-Watt test connectors and both circuits being standardized to 52 Ohms. This one was owned by the Canadian Army and probably disposed of shortly after 28 April 1994. That was the meter’s last calibration date with the next one noted as being due 15 July 1995. Missing the extension cable for the probe, one cover latch assembly and the Instruction Manual/ Card, which probably stored inside the cover with the probe and extension cable.

As much as it would have been fun to build the original Dummy Load, this is going to be so much easier.


David