Re: [IRCA] More phaser musings

["Bob Foxworth" <rfoxwor1@xxxxxxxxxxxxxxx>]

> >What kind of fine tuning controls do you have?  The Quantum Phaser I
> >have does not come with them.
> >
> >I tried it both ways, with and without the vernier drives.  I was
> >able to get deeper nulls with them. Sometimes just a hair made the
> >difference of 5 to 10 db.  That is critical in many situations.
> >
> >
> >Bill Harms


> Mine is a classic Misek design with 4 potentiometers....2 for course
tuning, and 2 for fine tuning.  They seem to work
great..............Walt.
> PS:  Normally they work fine with my "surgeon's touch", but when
nulling locals, your experience parallels my own.


Is this coarse/fine done by putting two pots in series, a high value
(maybe 5k?) and a low value (250 ohms)?  An alternative would be
to use a 10-turn pot with a mechanical counter dial, these can get
costly. The two pots would create an "electrical vernier" and the
10-turn pot a "mechanical vernier". I would think the "electrical
vernier" option could give better resolution, as some of the 10-turn
pots I remember were wirewound with a slider, OK for DC work but
maybe not so good for RF due to the inductance of the winding, and
the jumps in resolution. A wiper on a carbon strip inside a pot has
better continuous resolution.

What was the Misek design?

- Bob                      1433 est




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