"Brian Denley" wrote in message
...
Uncle Peter wrote:
Always do a "mechanical alignment" before doing an electrical one.
That is: check for loose couplers between the dial drives and caps,
make sure the dial pointer physically stops at the correct points at
the rotational stops... That the tuning capacitor plates are fully
unmeshed or meshed at the rotational stops (or as shown by the
manufacturer).

The Trimmer caps SHOULD allow you bring the high
end of the bands into calibration regardless of other issues... The
low end of the band alignment is usually set by the coil slug(s).

Pete



AND the coils and caps interact: if you adjust one significantly, you
have
to re-adjust the other. ALSO: if you are doing this with a sig gen, make
sure you are locking onto the actual freq, not some other mixer component
(happened to me).
--
Brian Denley
http://home.comcast.net/~b.denley/index.html



Interaction, true. However, if I recall, adjust the low end (coils) first.
The trimmers have least effect at the low end where the coils have effect
everywhere.

Starting like this usually means you won't have to do but this once. This is
predicated on the assumption that you are starting with a radio that has
been previously tuned and just needs touch-up; because the trimmer will be
"close".

73, Steve, K9DCI

Steve Nosko wrote:
"Brian Denley" wrote in message
...
Uncle Peter wrote:
Always do a "mechanical alignment" before doing an electrical one.
That is: check for loose couplers between the dial drives and caps,
make sure the dial pointer physically stops at the correct points at
the rotational stops... That the tuning capacitor plates are fully
unmeshed or meshed at the rotational stops (or as shown by the
manufacturer).

The Trimmer caps SHOULD allow you bring the high
end of the bands into calibration regardless of other issues... The
low end of the band alignment is usually set by the coil slug(s).

Pete


AND the coils and caps interact: if you adjust one significantly, you
have
to re-adjust the other. ALSO: if you are doing this with a sig gen, make
sure you are locking onto the actual freq, not some other mixer component
(happened to me).
--
Brian Denley
http://home.comcast.net/~b.denley/index.html



Interaction, true. However, if I recall, adjust the low end (coils) first.
The trimmers have least effect at the low end where the coils have effect
everywhere.

Starting like this usually means you won't have to do but this once. This is
predicated on the assumption that you are starting with a radio that has
been previously tuned and just needs touch-up; because the trimmer will be
"close".

73, Steve, K9DCI



I don't know if someone mentioned this I didn't see it but inside the
ceramic coil forms of the oscillator coils is a half turn of heavy wire
that you bend up and down within the cylinder of the form to aid or buck
inductance. Very stable good idea from National who, as I now find out,
had a much stabler almost drift free vfo with ceramic coils. (Unlike Halli)


Tony WA6LZH

Tony Angerame wrote:



I don't know if someone mentioned this I didn't see it but inside the
ceramic coil forms of the oscillator coils is a half turn of heavy wire
that you bend up and down within the cylinder of the form to aid or buck
inductance. Very stable good idea from National who, as I now find out,
had a much stabler almost drift free vfo with ceramic coils. (Unlike Halli)


Tony WA6LZH

I've got a coil here...not sure where it came from...possibly an LM or
BC221 freq meter that has a little internal winding on a mainspring
gizmo that rotates according to temperature. Quite clever.

-Bill