Wireless Set No. 52 Canadian - Project

[David Dunlop]

I am not certain how many other 52-Sets might be out there being brought back into operational condition. It can be a challenge in terms of available information and every little bit helps.

In getting back to work on my Sender this weekend, I ran across a little oddity regarding the metering circuits in the 52-Set.

On Page 127 of the Operators Manual, there is a Table of Voltage Readings provided for the Sender. For HT1, depending on Sender Settings, the range of values is from 290 Volts DC to 310 Volts DC. This initially struck me as interesting, but odd. The upper scale of the 52-Set meter is from 0 to 300 Volts DC only. I then noticed the voltage range for HT1 stated on the Table in Page 127 was 0 to 600 Volts DC. If this information was correct, then when reading Sender HT1 values on the 52-Set Meter, the indicated values on the meter would have to have a ‘x 2 Factor’ applied to them, and the metering circuits would have to be set up accordingly.

When running a no load test of the Sender (no valves present), my HT1 reading was a solid, steady 150 Volts DC. Apply a ‘x 2 Factor’ and I get a perfect 300 Volts DC, which I was quite pleased with. I ran this information by Jacques Fortin and he checked the documentation and circuit diagrams. Sure enough, he found no evidence either of this metering design being mentioned in the manuals, and did confirm when the Receiver Meter Switch is on SENDER and the Sender Meter Switch on HT1, a pair of 600K resisters are brought into the circuit in series giving it a 600 Volt rating as per the Sender Voltages Table in the Operators Manual.

I am now going to start reinstalling the valves back into the Sender one at a time, starting at the front end of the block diagram. With all of them in place originally, one of the operational Tests for the Supply Unit had the two dynamotors running with 300 Volts HT1 just nicely, the next test up, however, had a massive load hit the dynamotors on startup and the indicator lamps nearly went out. And the HT1 reading was an alarming 180 Volts DC.

More as the saga unfolds.


David