You may have noticed a lack of postings lately. Some of that is certainly due to Life getting in the way of Hobbies from time to time, but in this instance, the bulk of it is simply me, having to shift gears from a ‘Mechanical/Physical Restoration Train of Thought’ to getting my brain wrapped back around the actual electronics of the project once again. I have been away from that for a year or so now and it shows. Sketchy surviving 2nd to 4th Echelon Documentation for the 52-Set does not help much either.
With the receiver portion of the project, I do have the benefit of three on hand. The Remote Receiver is performing very well and has become my benchmark to compare the Main Set receiver to, in the course of getting it back up and running. Parts of the Main Set receiver are working well. Others barely. The net result is lots of controllable static audio output. End of story.
The third receiver is the Parts one. Useful for comparisons to the other two.
Most of my time recently has been spent designing Spreadsheets on Excel to log data into, as I collect it from the Remote and Main Set Receivers. The general plan is to log as much information as I can from the Remote Receiver and then compare the same data from the Main Set Receiver to try and narrow down significant anomalies for more detailed investigation.
So far, all valves in both sets have been tested and the Meter Readings of each receiver recorded, along with the relevant resisters in the meter circuits. The valves are all rating as new and several resisters in the meter circuits of the Main Set Receiver will need replacement.
I am now completing a pin-by-pin analysis of all the valves in the Remote receiver for both Voltage and Resistance measurements. That work has been done with the exception of V1A and half of V1B. These two sockets are hiding up behind the 8-Pin Connector assembly, which will have to be unscrewed from the chassis and swung away to complete the tests.
Then I can repeat the process with the Main Set Receiver and narrow down significant variations for a closer look.
While doing this work, I was chatting with Jacques Fortin and he asked if any of the receivers had Modification Instruction 6 Performed on them. I had forgotten about this one. It was issued 24 April 1959, and involved replacement of the 10 original 100 uuF Trimmer Capacitors in the IF, BFO and Detector stages of the Receiver.
The originals, a semi-fixed 5-100 uuF capacitor were found to be defective and were to be replaced with a newer improved variable, air dielectric 7.5 to 99.9 uuF capacitor.
The distinguishing characteristics between these two sets of variable capacitors visually, is the originals had a flat zinc plated finish on the tuning shafts and locking nuts and the shafts stuck out beyond the locking nuts about one quarter inch. The new replacement trimmers have a bright nickel finish and the shafts sit flush with the locking nuts.
The Modification Cards in my Remote Receiver and Parts Receiver confirmed the change was done in 1961 on the remote Receiver and never done on the Parts one. The first two photos attached show the originals in the Parts Receiver and the second set of photos show the upgraded capacitors in the Remote Receiver. C7A to C7H can be found in two banks of four at the back of the chassis. C7K and C7J are found, left to right, at the front of the chassis on the extreme left directly above the retaining clamp for valves V1G and V1H. No letter “I” was used in the coding system for these trimmers.
I thought I would post this information in case anyone has a 52-Set Receiver with no Mod Card. They can at least now determine if their receiver was modified or not.
David
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