There are at least three versions of the Wunderlich tube. The tube is a
dual grid detector used during the early 1930s to accommodate an early
application of AVC. Versions included 2.5-volt and 6.3-volt types with
six pins on the base and a five pin version with a grid cap (I don't
recall the heater voltage of this version). The 6-pin 6.3-volt version
can usually be identified by a star marked on the top of the globe or
the word "automotive" engraved on the base. The most common application
was as a detector and AVC tube in the E.H. Scott Allwave Deluxe (AKA
AW-12, one dial). The 6-pin, 2.5-volt version was used in this
receiver. The 6.3-volt versions were marketed for use in automobile
receivers. I can recall seeing the schematic for one Majestic home
receiver having a Wunderlich tube.
Once the version and heater voltage is known, the best method of testing
the Wunderlich tube is to substitute it into a working receiver. This
isn't exactly easy even if it is a 6-pin, 2.5-volt version because there
aren't that many Scott receivers around in which to test them. Some
mid-1930s tube testers included settings for testing the Wunderlich tube
but most were emissions testers. The Hickok AC-51 and a couple other
early Hickok tube testers (mutual conductance) also included settings
for the Wunderlich but these are not much more common than the Scott
receivers and I'm not sure the setting will translate to other models.
Norman
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Post by N***@attbi.comI think Wunderlich tubes have a number that one can use the find the
settings to test them with. Anyone know what it is? Thanks.
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