Re: [IRCA] "Hot-Rodded" DT-200VX Digital ULR is a Reality

["Gil Stacy" <gilstacy@xxxxxxxxx>]

Mike,

The center tap may not be for the oscillator.  For instance in the
39/49/59's the ferrite bar has 5 leads as well.  Two connect the short coil
to the long coil in series.  Two leads are the far ends of the connected
coils and these go across the variable capacitor.  I assume the M37 is
varcator diode driven to introduce capacitance.  The smaller coil is moved
along the ferrite bar to fine tune inductance for  proper matching to ensure
tracking.  The tapped lead is most likely there to keep signal load down and
goes directly to AM RF pin. ( Until I hear a better theory.  Transformer for
impedance match?).
In the analogs above, the Oscillator coil is an IF can, L3.

73 Gil
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