Message-ID: <4CCD3CEA.5020200@iup.uni-heidelberg.de>
Date: Sun, 31 Oct 2010 10:54:50 +0100
From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= <schaefer@iup.uni-heidelberg.de>
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References: <4CCC8022.90003@iup.uni-heidelberg.de> <004e01cb7883$96949580$4001a8c0@lark>,<4CCCA351.1070508@iup.uni-heidelberg.de> <BF4A524700075746A6467658DFC7102C886E0FF542@ICTS-S-EXC2-CA.luna.kuleuven.be>
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Subject: Re: LF: Re: SBL-3+
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Hi Rik,

Very interesting! Looks easy, almost perfect. But i don't know what is=20
the "best" solution now. It gets confusing the more solutions become=20
available. Probably each method can achieve optimal results if built=20
correctly. I think i will try a lot in the next days..

Tnx!

73, Stefan

Am 31.10.2010 10:42, schrieb Rik Strobbe:
> Hello Stefan, Alan,
>
> what about a CMOS analog switch mixer ? Cheap and easy to find.
> I used a 74HC4053 as mixer in my 3.5MHz to 500kHz transverter.
> Have a look at http://home4.swipnet.se/~w-41522/lfconv/lfconv.html (SM6L=
KM), wher Johan shows a LF to 4MHz converter with a 74HC4053 mixer. Just=
 adapt the LO and output circuitery for LF output.
>
> 73, Rik  ON7TD - OR7T
>
> ________________________________________
> Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.=
org] namens Stefan Sch=E4fer [schaefer@iup.uni-heidelberg.de]
> Verzonden: zondag 31 oktober 2010 0:59
> Aan: rsgb_lf_group@blacksheep.org
> Onderwerp: Re: LF: Re: SBL-3+
>
> Hi Alan,
>
> I want to try an alternative to the BF981 which runs in my current LF
> grabber RX. It downconverts 137 kHz to 12 kHz and feeds the soundcard
> with this 12 kHz signal. It is running not too bad but i have some
> problems with temperature drifting bandpass filters (since weeks) and
> have thrown them out of the Drain-to-Plus path. So, now the setup is
> running with a 2 stage RC LPF. I have had some problems with a to high
> 125 kHz level on the soundcard input and have applied a series LC
> circuit for 125 kHz now which reasonably solved the problem. But the LF
> noise is now just about 10 dB above the soundcard noise, in the
> afternoon. There is still a lack of sensitivity. This RX QTH should be
> very well for a grabber antenna but currently the setup is the problem.
> So i want to try something different, like a DBM. I am not an expert
> here and can/have to learn a lot, it seems ;-)
>
> 73, Stefan
>
> Am 31.10.2010 00:41, schrieb Alan Melia:
>   =20
>> Hi Stefan why a difficult to get mixer?? the IF port on most DBMs is DC
>> coupled so feed the siganl in there and (i presume) mix up ?? Or is the
>> RF/LO response still too high on the easily available ones?
>>
>> Alan G3NYK
>> ----- Original Message -----
>> From: "Stefan Sch=E4fer"<schaefer@iup.uni-heidelberg.de>
>> To:<rsgb_lf_group@blacksheep.org>
>> Sent: Saturday, October 30, 2010 9:29 PM
>> Subject: LF: SBL-3+
>>
>>
>>
>>     =20
>>> Dear LF,
>>>
>>> I want to try a LF converter using this mixer. Does anybody know a
>>> (cheep!) distributor in Germany or EU for 1...3 pieces of it? I've jus=
t
>>> found one where it costs about 40 Euro and this is to much!!
>>>
>>> 73, Stefan/DK7FC
>>>
>>>
>>>       =20
>>     =20