Hi Martin,
Am 11.01.2012 21:44, schrieb Martin Evans:
I use a decade inductance bridge to series tune my (approximately)
50m end-fed inverted U wire for 137kHz.
It uses 3mH - 2mH is too little, 4mH is too much. Obviously I need to
be able to vary this inductance rather more finely and I thought of
using a small variac (don't laugh!) as a variable inductance,
connecting one end, and the tap, in series with the wire.
Anyone know what the "inductance per turn", or total inductance, of
such an animal might be?
The L will be much to high and the Q will be very low (=lossy). Also it
has a high parsitic C and will have a self resonance below 137 kHz. So
it rather acts like a capacitor.
BTW capacitor, this is what i suggest. Simply use the 2 mH and a small
variable capacitor connected to the wire and GND. Then you can
accurately adjust to LF.
Unfortunately i can't generate a reasonable test signal for you tonite
but there are a lot of UK transmitting stations :-)
Any idea if it would work?
Yes, NO.
73, GL, Stefan/DK7FC
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