"Paul Keinanen" wrote in message
...
On Tue, 23 May 2006 12:16:27 +0100, "Reg Edwards"
wrote:

Replace the meter scale with a white card and calibrate it yourself
with pen and ink. You will also need a signal generator and an
attenuator.

If you derive the S-meter reading from the a.g.c. control voltage,
be
prepared to perform the calibration at various temperatures, since
the
gain of simple IF-strips vary with temperature (and thus need a
different amount of a.g.c.), unless the gain is controlled by
passive
components only.

With various front end filter for various frequency bands and
attenuation depending of the frequency, you would have to perform
the
calibration on several frequencies.

Instead of a pen and ink, it would be more practical to use a micro
controller with sufficient non-volatile storage for the conversion
tables and use analog inputs for a.g.c. voltage and temperature and
some kind of input for the frequency being received. With these
inputs
and the conversion table, a voltage proportional of the log of the
antenna terminal power could be generated.

Paul OH3LWR
===========================================

I don't doubt that the problem is capable of being solved.

Just throw enough electronic hardware and software at it.

The cost can be estimated at 100,000 Euros.

The size and weight of the receiver will be quadrupled.

No amateur would be able to afford buying one.

American tax-payers would prevent NASA from doing the research and
development work. Even Bush would object.

As for me and most other amateurs, I'm quite happy with an S-meter
reading which puts signal strength reports in the right ball-park.
Very strong, very weak, or indifferent.
----
Reg.