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Per my ongoing research, I have determined that there was at least one self-contained Post-Marker sweep generator system which was compatible with 24 MHz IF systems. That unit was the Eico model 369.
The Eico 369 also produced its sweep output via a fully-electronic modulation circuit, eliminating all of the potential mechanical issues associated with the "EMR" modulation systems used in many other instruments of similar vintage. The only "moving parts" in these units are their operating controls and switches.
Since the Eico 369 was available in factory-built and kit form, there are potential "workmanship issues" with a unit which was built from a kit. Most of these are easy to spot and correct during recapping and calibration, however. Also, if the Scope cable is missing, the "Twinax" connector (similar to the one RCA used for RF Out on the WR-69A) required for making a replacement cable may be difficult to find.
Post-Marker upgrade instructions for the model 368 were also featured as a project article the April, 1969 issue of Service magazine. I have just bought an Eico 368 with the Service magazine upgrade installed and with all accessories and documentation included. The unit was shipped Monday afternoon via USPS, so I expect its arrival in about a week.
In my original post on this topic, I described one method of obtaining a multi-marker display using two marker sources, and the IF system used in the example was RCA. When aligning a Dumont receiver, the 750 kHz "Interval" frequency will remain constant and the "Master" marker frequency should be set to 24.15 MHz per the following calculation, where "F" is the unknown Master frequency to be used and "P" is the known Picture Carrier IF value from the Service Manual of the set to be aligned (P = 26.40 MHz for most Dumont chassis):
F=(P-25.75)+23.50
The third marker on each side of center will be the correct Sound and Picture carrier marker respectively for the chassis under test. The fifth marker from each side of center will be at the correct Adjacent Picture and Adjacent Sound trap marker positions.
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