[AMRadio] Strange oscillator?


Alan Victor amvictor at ncsu.edu
Fri Dec 16 12:23:14 EST 2011


Consider the whole circuit and the NET reactance change. It is possible
that although the powered iron increases the L and hence the reactance, the
resulting capacitive reactance change is such that the frequency
INCREASES... again you need to look at the whole network and think in terms
of reactance change.

On Fri, Dec 16, 2011 at 8:47 AM, CL in NC <mjcal77 at yahoo.com> wrote:

> I've got this old Regency R75 RX I am going through.  The LO operates at
> 455 below the signal freq. What type of oscillator goes up in freq when you
> back the slug out of a coil form, or down in freq. when you loosen a
> trimmer cap?  You can see this on a counter too.  I have one of the old
> tuning wands, powdered iron on one end, brass on the other, you put the
> brass end into the coil form and it goes down in freq, iron end into the
> form and it goes up.  I reviewed all my osc. circuits, but this one seems
> to defy the resonance formula.
>
> charlie W4MEC in NC
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