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Date: Sat, 15 Sep 2012 02:06:49 +0200
From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= <Stefan.Schaefer@iup.uni-heidelberg.de>
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Subject: Re: LF: Re: RE: MF tonite
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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). Thus=20
i decided to rebuilt the circuit as it has been before and will=20
eventually use an uptransformer behind the filter. But probably this is=20
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=E4f=
er
> 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 affec=
t
> the matching, i would prefer that...
>
> 73, Stefan
> Am 13.09.2012 20:43, schrieb Ken:
>   =20
>> Stefan.
>> Thank you for the info, maybe sometime you will be able to post the
>>     =20
> circuit?
>   =20
>> 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
>>
>>     =20
> https://dl.dropbox.com/u/19882028/MF/Mechanical_filter_with_source-foll=
owers
>   =20
>> .JPG
>> The results have been very good last night!
>>
>> 73, Stefan/DK7FC
>>
>>
>> Am 13.09.2012 13:12, schrieb Thomas Rosenkranz:
>>
>>     =20
>>> 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 Sch=E4=
fer
>>> 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 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 input =
and
>>> output, to provide a constant accurate impedance matching to keep the
>>> passband ripple as low as possible. The afternoons tests have been ve=
ry
>>> promising, see https://dl.dropbox.com/u/19882028/MF/MF%20Filter.png
>>> This is the frequency response:
>>>
>>>       =20
> https://dl.dropbox.com/u/19882028/MF/473%20kHz%20ZF%20Filter%2040%20dB.=
png
>   =20
>>>
>>>       =20
>>
>>     =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
>>>       =20
>>     =20
>
>   =20