Hello group,
Here a picture of my new LF frontend of my active antenna,
http://dl.dropbox.com/u/19882028/LF/LF%20frontend.jpg
It has a 2 stage bandpass filter in front of the first FET stage (BF862
which is located on the back side). The Q is not very high but DLF and
DCF49 are attenuated by about 15 dB. Additionally it provides a kind of
HV protection, i hope ;-) But the main purpose is to filter VLF and MF
and HF. On the older version i regularly saw MSK traces arround 136.6
kHz. This is 153 kHz (DLF) minus 16.4 kHz (JXN)! :-)
After some test time it moves in a water proof PVC tube now and is
intended to run 24/7 on the grabber as the omnidirectional antenna.
Further improvements will be done in the shack, perhaps.
73, Stefan/DK7FC
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