Wireless Set No. 52 Canadian - Project

[David Dunlop]

I have been looking at the test results for Valve V7A (the 813) this morning. It is quite a comprehensive set of tests in its own right for this valve. Everything gets checked twice, in each of the Power Settings, LOW, MEDIUM and HIGH and the Mode of Operation Switch set to RT. Then you repeat the tests with the Mode of Operation Switch at any of its other settings, M.C.W., CW or BREAK IN.

What I finally noticed was that the vast majority of the extremely excessive readings I got took place in the RT Mode. By excessive, I mean results that should have been 10,000 Ohms, or between 1 and 2 Megs, were coming back 25, 200, 500 Megs or Infinity.

Something definitely is not right. The test indications of an excess load lurking somewhere match up with the observation of the Supply Unit being hit with a massive load with both Dynamotors running in SEND Mode in order to check proper operation of the Receiver Isolation Relay. That prompted a quick shut down of the set as soon as proper function of the relay was heard. A careful visual examination of the Sender shows no heat discolouration anywhere. Nor are there any burnt smells anywhere, and the Supply Unit continues to function nicely with the Sender out of the Carriers No. 4 circuit and on the bench alone.

I do wonder if the Mode of Operation Switch may have a buildup of oxidation on its terminal wafer connections that I missed, so to rule that out, I am going to give that switch a couple of cleanings with Dioxit today and then repeat the set of tests for V7A. Nothing may change, but at least I can rule the possibility out and know the Mode of Operation Switch will now be nice and clean.


David