90501 Secondary Frequency Standard

The Millen frequency standard probably didn't see much use in the ham shack as it did it the laboratory environment. It has an adjustable RF output in intervals of 10, 25, 100 and 1000 Kcs with useful signal strength to 50 Mcs. It also incorporates an internal 800 cycle audio generator/modulator and a detector with phone jack. The unit runs from a very stable helium filled 1000 Kcs vacuum quartz oscillator and uses synchronized multivibrator oscillators to create the 10, 25 and 100 Kcs markers.

I've noticed that there appeared to be different designs produced which changed the RF output and modulator input connector types. The variation model 90505 appeared in the 1952 ARRL Handbook used single ceramic base quick release binding posts. As you can see this unit has both black bakelite banana jack and standard SO-238 connectors. At first I thought that the SO-238's were add-ons by a previous owner, but after disassembling the unit the workmanship appears to be very professional and I would surmise it was an original Millen variation.

Owner: Don Buska, N9OO

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