Hi Alberto,
Interesting. Keep us informed about your results with the short active
dipole. I've never tried such an antenna so far. But maybe it could be
an idea, if the ground is QRM-contaminated...
73, Stefan/DK7FC
Am 23.02.2012 15:10, schrieb Alberto di Bene:
On 2/23/2012 2:30 PM, Stefan Schäfer wrote:
Hi Alberto,
That looks fine. I'm glad to get a report from you, thank you.
How long was that wire and was it in the house or outside? :-)
Hi Stefan,
oh, that wire was just a dipole for the 40m band, directly connected
to the receiver, without any form of tuning for the 137kHz band.
Signals are low, but so also is the noise... :-)
Often is advantageous to have a not so high gain antenna... the S/N
ratio can improve... not always, but sometimes yes.
That dipole is low in height. Actually it is an inverted V, with the
apex at 10m from the ground.
For the LF band I have also a mini whip, temporarily out of service, as
I used the coax feeding it for some tests of a differential active
antenna,
with two beer cans spaced abt 1.5m connected to the differential inputs
of a high impedance amplifier. It works quite well, as it does
not need to be referred to a ground potential, but maybe I have to
change the schematic of that transimpedance amplifier, as it
exhibits more intermodulation that I thought it should have....
73 Alberto I2PHD
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