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Date: Sat, 15 Sep 2012 02:24:25 +0200
From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= <Stefan.Schaefer@iup.uni-heidelberg.de>
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To: rsgb_lf_group@blacksheep.org
References: <h0drfa73usb6ft8xspd0sl8j.1347476481893@email.android.com> <5050EA23.1040802@iup.uni-heidelberg.de> <EF76E5CF7FCB43F38C1CF49114119176@lindavideo> <62B8952382DF4DB294DF41CA351C4188@Notebook> <5051C2B6.8080303@iup.uni-heidelberg.de> <067BD06E05C54207A184D8CB4BFEB066@lindavideo> <50522DF1.9050502@iup.uni-heidelberg.de> <0FEA5D7549D94AA398184E6DEACDA6EE@lindavideo> <5053C699.6090300@iup.uni-heidelberg.de>
In-Reply-To: <5053C699.6090300@iup.uni-heidelberg.de>
Subject: Re: LF: Re: RE: MF tonite
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PS: You know, you can use the input stage directly as an active E field=20
antenna which is for MF only. You would prevent the overload of a poor=20
RX by MF AM BCD stations...

73, Stefan

Am 15.09.2012 02:06, schrieb Stefan Sch=E4fer:
> Hi Ken,
>
> I just tried to use the 500 Ohm input and the 18k Ohm output. It works=20
> UFB but then i got worried about destroying the filter due to the=20
> up-transformation on the input (the max. input voltage is 2 V rms).=20
> Thus i decided to rebuilt the circuit as it has been before and will=20
> eventually use an uptransformer behind the filter. But probably this=20
> is not necessary because the MF noisef floor is still 20 dB above my=20
> RX+soundcard noise floor...
>
> After readjusting the C, now the passband ripple is < 0.5 dB.
>
> This is the schematic:=20
> https://dl.dropbox.com/u/19882028/MF/MF%20Filter%20schematic.png
> (You know, someone has done it all before and it is nothing new ;-) ).
>
> Will you order and use some of them?
>
> 73, Stefan/DK7FC
>
> Am 13.09.2012 21:47, schrieb Ken:
>> Hi Stefan.
>> Fully understand.
>>
>> 73.
>> Ken.
>> M0KHW
>>
>> -----Original Message-----
>> From: owner-rsgb_lf_group@blacksheep.org
>> [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Stefan Sch=E4=
fer
>> Sent: 13 September 2012 20:03
>> To: rsgb_lf_group@blacksheep.org
>> Subject: Re: LF: Re: RE: MF tonite
>>
>> Hi Ken,
>>
>> OK but later. I want to try some modifications, i.e. using the 500 Ohm
>> input and the 18 kOhm output, to have some gain. If this does not affe=
ct
>> the matching, i would prefer that...
>>
>> 73, Stefan
>> Am 13.09.2012 20:43, schrieb Ken:
>>> Stefan.
>>> Thank you for the info, maybe sometime you will be able to post the
>> circuit?
>>> 73.
>>>
>>> Ken
>>>
>>> M0KHW
>>>
>>> -----Original Message-----
>>> From: owner-rsgb_lf_group@blacksheep.org
>>> [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Stefan Sch=E4=
fer
>>> Sent: 13 September 2012 12:26
>>> To: rsgb_lf_group@blacksheep.org
>>> Subject: Re: LF: Re: RE: MF tonite
>>>
>>> Ah yes, Thomas was faster, damn ;-)
>>>
>>> Another image from the experimental setup, using source followers
>>>
>> https://dl.dropbox.com/u/19882028/MF/Mechanical_filter_with_source-fol=
lowers=20
>>
>>> .JPG
>>> The results have been very good last night!
>>>
>>> 73, Stefan/DK7FC
>>>
>>>
>>> Am 13.09.2012 13:12, schrieb Thomas Rosenkranz:
>>>
>>>> Hy Ken,
>>>>
>>>> the name of the mechanical filter is FZ02
>>>> http://www.oppermann-electronic.de/html/hf-spezialbauteile.html
>>>>
>>>> http://dm4tr.bplaced.net/index.php?section=3DReceiver
>>>>
>>>> 73
>>>> Thomas DM4TR
>>>>
>>>>
>>>> ----- Original Message ----- From: "Ken"<ken.h.wright@btinternet.com=
>
>>>> To:<rsgb_lf_group@blacksheep.org>
>>>> Sent: Thursday, September 13, 2012 10:28 AM
>>>> Subject: LF: RE: MF tonite
>>>>
>>>>
>>>> Hi Stefan.
>>>> What mechanical filter are you using?.
>>>> 73.
>>>> Ken
>>>> M0KHW
>>>>
>>>> -----Original Message-----
>>>> From: owner-rsgb_lf_group@blacksheep.org
>>>> [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Stefan=20
>>>> Sch=E4fer
>>>> Sent: 12 September 2012 21:02
>>>> To: rsgb_lf_group@blacksheep.org
>>>> Subject: LF: MF tonite
>>>>
>>>> Christian,
>>>>
>>>> Are you QRV tonite? I would like to see or better hear the=20
>>>> difference of
>>>> my RX performance when using my band filter i was testing in the
>>>> afternoon.
>>>>
>>>> It is the mechanical filter which uses source followers at the=20
>>>> input and
>>>> output, to provide a constant accurate impedance matching to keep th=
e
>>>> passband ripple as low as possible. The afternoons tests have been=20
>>>> very
>>>> promising, see https://dl.dropbox.com/u/19882028/MF/MF%20Filter.png
>>>> This is the frequency response:
>>>>
>> https://dl.dropbox.com/u/19882028/MF/473%20kHz%20ZF%20Filter%2040%20dB=
.png=20
>>
>>>>
>>>
>>>> There should be a much better image rejection now and so maybe a few
>>>> more dB SNR... Unfortunately the filter does not cover the 502 kHz
>>>> region. But this problem will be gone in some months...
>>>>
>>>> Will be on 472.5 kHz soon.
>>>>
>>>> 73, Stefan/DK7FC
>>
>