90651 Grid-Dip Meter
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This is the first of the Millen Grid-Dip Meters. Released to the public in mid-1949.
It was designed by Wilfred Scherer, W2AEF and appeared in a number of CQ magazine
articles. Utalizing vacuum tube technology the 90651 requires main AC power to operate.
On the top side is a drum dial which is calibrated into seven scales for a frequency
coverage from 1.5 Mc to 300 Mc. This seven band coverage is achieved through plug-in
coil assemblies which can be seen in the upper picture. In addition, inclusion of
one arbitrarily marked scale which is used with optional coils allowing coverage
down to 220 Kc. I'm not sure of manufacturing figures, but the 90651 was a very
popular item manufactured by Millen for the communication field. A later version
90651A was produced which added a sensitivity control to the unit. The pictures were supplied by Dave Schneider which shows his 90651 in an original carrying case. Dave's unit is also equipped with the optional LF coils. |