Return to KLUBNL.PL main page

rsgb_lf_group
[Top] [All Lists]

Re: LF: Re: RE: MF tonite

To: [email protected]
Subject: Re: LF: Re: RE: MF tonite
From: Stefan Schäfer <[email protected]>
Date: Sat, 15 Sep 2012 02:24:25 +0200
In-reply-to: <[email protected]>
References: <[email protected]> <[email protected]> <EF76E5CF7FCB43F38C1CF49114119176@lindavideo> <62B8952382DF4DB294DF41CA351C4188@Notebook> <[email protected]> <067BD06E05C54207A184D8CB4BFEB066@lindavideo> <[email protected]> <0FEA5D7549D94AA398184E6DEACDA6EE@lindavideo> <[email protected]>
Reply-to: [email protected]
Sender: [email protected]
User-agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3

PS: You know, you can use the input stage directly as an active E field antenna which is for MF only. You would prevent the overload of a poor RX by MF AM BCD stations...

73, Stefan

Am 15.09.2012 02:06, schrieb Stefan Schäfer:
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




<Prev in Thread] Current Thread [Next in Thread>