[R-390] Honey I Shrunk the VFO (tuning range)
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[email protected]
Sun, 26 Jan 2003 13:32:31 EST
<PRE>I have read discussions of the R-390 and other Collins VFO
end-point-adjustment. I wonder if we could all settle on what happens with
the tuning range? Some people say adding inductance "shrinks" the tuning
range, others say it "expands" the tuning range. To be correct wouldn't
adding inductance "shrink" the actual tuning range? If you have a VFO that
starts out at 0000 and you have to crank it up to +0009 to get exactly 1 MHz
of change, the VFO tuning range has actually "shrunk". That means with
exactly 10-turns of the tuning knob, the VFO RANGE of coverage was only 991
KHz. You will have to "expand" the tuning range so that 10-turns of the VFO
will cover a full 1 MHz. It sounds counter-intuitive from the numbers on the
counter dial. When you turn the endpoint adjustment slug clockwise you are
LOWERING the inductance - thus "expanding" the range of the VFO = it will
cover more frequency range in the same 10-turns of rotation. Likewise if
someone has to resort to removing 1-turn or more from the End-Point
adjustment slug you are lowering the inductance = expanding the tuning range
of the VFO. Hope I have this right! 73 Todd Roberts WD4NGG.