Hi Hugh,
You don't say what other instruments you have available,
but here are a few suggestions:
1. Measure the RF voltage across the dummy load with a scope.
Determine current by knowing or measuring its resistance.
A dummy load usable at 10 meters should be very close to
its DC resistance at 1.8 MHz.
2. Measure how hot the dummy load gets, then see how much
DC or mains frequency current it takes to produce the
same final temperature.
3. Put a suitable light bulb in series. Measure the brightness
with a light meter, then see how much DC or mains frequency
current it takes to produce the same brightness.
4. Rig a simple diode rectifier to measure the RF voltage.
Either compensate the reading with an estimate of the diode
drop, or calibrate the rectifier at mains frequency.
73,
Stewart KK7KA
----- Original Message -----
From: "g6tmk" <[email protected]>
To: <[email protected]>
Sent: Friday, November 15, 2002 11:33 AM
Subject: LF: Calibrating LF Current Meters
Hi All,
I built the little antenna current meter shown in the LF Experimenters
Handbook last night (Page 81).
And it works. I measured the current from my HF rig into a dummy load at
1.8MHz, and it gave sensible results ...
But how can I calibrate it - how do I know that an indicated Amp really is
an Amp.
My DVMs, being intended for mains current measurement, don't have the
frequency response.
How have other people done it ? Any ideas ?
73
Hugh M0WYE
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