Re: LF: Lf Frontend

[Stefan Schäfer <Stefan.Schaefer@iup.uni-heidelberg.de>]

Hello Lubos,

Yes it works but obviously the plastic housing is to small and so a capacitor was moving the resonance down. HGA22 was so strong it peaked the 0 dB mark of my soundcard and caused strongest IM in the night. Furthermore it is raining now and the raindrops seem to move the resonance down even more. Seems i have to put the circuit back into a metallic housing where it worked well in the last days...

73, Stefan/DK7FC

Am 12.05.2011 05:51, schrieb Lubos OK2BVG:

Hello Stefan!

It is interesting, thanks for information and nice picture.

Lubos, OK2BVG

BTW: It seems, my grabber works.

*******************************************  

> Date: Wed, 11 May 2011 16:42:46 +0200
> From: Stefan.Schaefer@iup.uni-heidelberg.de
> To: rsgb_lf_group@blacksheep.org
> Subject: LF: Lf Frontend
>
> 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
>