Re: LF: Measuring Q

[G0MRF@aol.com]

In a message dated 11/21/01 8:35:15 AM GMT Standard Time, g3ldo@ukonline.co.uk writes:


> I connected the coil under test with a parallel air-spaced capacitor to the
> signal generator via a variable capacitor. I coupled the coil to the level
> meter with with just a clip on the insulation of the coil. I reduced the
> coupling to the signal generator with the variable capacitor to minimum
> while maintaining a good signal on the level meter.


Hello Peter.

I tried something similar about a year ago and found that any direct connection to the coil under test affected the results. Seems from your description you have some connections which may be influencing the results.

As a start I would suggest you try link coupling the signal in from the generator.

The 'sample' output is the other problem.
My solution was to use a capacitive divider......An airspaced variable in series with a large mica capacitor. The junction has a low impedance. Even so I used a 1M resistor then coupled that to a high Z oscilloscope.  The results were OK to a Q of 350 but after that it became unreliable.

Let us know if you resolve the problems.

GL es 73

David  G0MRF