Stefan,
Is there an audible better Performance of ur rx with the mechanical filter?
73, df5qg
Christian Groeger
Stefan Schäfer <[email protected]> schrieb:
>Hi Ken,
>
>I just tried to use the 500 Ohm input and the 18k Ohm output. It works
>UFB but then i got worried about destroying the filter due to the
>up-transformation on the input (the max. input voltage is 2 V rms). Thus
>i decided to rebuilt the circuit as it has been before and will
>eventually use an uptransformer behind the filter. But probably this is
>not necessary because the MF noisef floor is still 20 dB above my
>RX+soundcard noise floor...
>
>After readjusting the C, now the passband ripple is < 0.5 dB.
>
>This is the schematic:
>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: [email protected]
>> [mailto:[email protected]] On Behalf Of Stefan Schäfer
>> Sent: 13 September 2012 20:03
>> To: [email protected]
>> 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 affect
>> 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: [email protected]
>>> [mailto:[email protected]] On Behalf Of Stefan Schäfer
>>> Sent: 13 September 2012 12:26
>>> To: [email protected]
>>> 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-followers
>>
>>> .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=Receiver
>>>>
>>>> 73
>>>> Thomas DM4TR
>>>>
>>>>
>>>> ----- Original Message ----- From: "Ken"<[email protected]>
>>>> To:<[email protected]>
>>>> 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: [email protected]
>>>> [mailto:[email protected]] On Behalf Of Stefan Schäfer
>>>> Sent: 12 September 2012 21:02
>>>> To: [email protected]
>>>> 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 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
>>
>>>>
>>>>
>>>
>>>
>>>> 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
>>>>
>>>
>>
>>
>
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