Message-ID: <505791B4.5060003@iup.uni-heidelberg.de>
Date: Mon, 17 Sep 2012 23:10:12 +0200
From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= <Stefan.Schaefer@iup.uni-heidelberg.de>
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3
MIME-Version: 1.0
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> <08B3DCF1255E403E84FBD7FCBD3C2803@lindavideo> <50565EF3.9020809@iup.uni-heidelberg.de> <102E3FCB55DA418EA074CBFAEB59FA84@lindavideo>
In-Reply-To: <102E3FCB55DA418EA074CBFAEB59FA84@lindavideo>
Subject: Re: LF: Re: RE: MF tonite
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: quoted-printable
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org


Hi Ken,

OK, but if you have no problems with the current filter, you will have=20
no problems on 472 as well. So it might be sufficient just to readjust=20
it to the new band next year.
Anyway, the mechanical filter looks even much better. I like the very=20
the low passband ripple :-)

73, cul, Stefan/DK7FC

Am 17.09.2012 22:42, schrieb Ken:
> Hi Stefan.
>
> I have resent this reply, I think the original with an attachment may h=
ave
> been blocked
> The answers to your questions are.
>
> My RX is a Kenwood TS140S.
>
> Antenna, 102ft doublet centre fed with 470 ladder feeder, strapped as a=
 T
> for 500 kHz working.
>
> Because the antenna is never connected to any equipment when the statio=
n is
> unattended there are only two GE diodes across the filter input.
>
> The filter characteristics as follows,  f0 =3D 501.87kHz.
>
> 3dB  495.71 kHz - 508.26 kHz
>
> 6dB  492.77 kHz - 511.29 kHz
>
> 12dB 486..89 kHz - 516.99 kHz
>
> 18dB 479.20 kHz - 523.83 kHz
>
> 24dB 468.43 kHz - 532.522 kHz
>
> 30dB 453.97 kHz - 543.25 kHz
>
> It was the BC stations around 530 kHz which were causing the problems
>
>
> 73s,
>
> 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: 17 September 2012 00:21
> To: rsgb_lf_group@blacksheep.org
> Subject: Re: LF: Re: RE: MF tonite
>
> Hi Ken,
>
> My thoughts,
>
> Am 16.09.2012 22:07, schrieb Ken:
>   =20
>> Hi Stefan.
>> Thank you for all the filter info, definitely interested in them, at
>>     =20
> present
>   =20
>> for 500kHz I have a homebrew filter using two Toko transformers in bet=
ween
>> the antenna socket and two stage rx pre-amp.
>>     =20
> What RX are you using? And what type of antenna?
>   =20
>>    There are GE protection diodes
>> across the input,
>>     =20
> I should think about that too. 3x Si diodes in series, 2x, antiparallel.
>
>   =20
>>    the pre-amp gain is 0 - 18dB with a variable capacitor to
>> peak at the operating frequency.
>>     =20
> What is the BW of that peak?
>   =20
>>    I was thinking of replacing the 500kHz
>> filter with this mechanical one, it would save work, just need an inpu=
t
>> matching Xformer and change the gate resistor on the input FET.
>>
>>     =20
> Yes, the input resistor value can be choosen in a very wide range. Yes,
> you can use a input Xformer to get some gain.
>
> 73, Stefan/DK7FC
>
>
>   =20
>> Your thoughts please Stefan.
>>
>> 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: 15 September 2012 01:07
>> To: rsgb_lf_group@blacksheep.org
>> Subject: Re: LF: Re: RE: MF tonite
>>
>> 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). Th=
us
>> i decided to rebuilt the circuit as it has been before and will
>> eventually use an uptransformer behind the filter. But probably this i=
s
>> 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:
>>
>>     =20
>>> 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 Oh=
m
>>> input and the 18 kOhm output, to have some gain. If this does not aff=
ect
>>> 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
>>>
>>>       =20
>>     =20
> https://dl.dropbox.com/u/19882028/MF/Mechanical_filter_with_source-foll=
owers
>   =20
>>
>>     =20
>>>
>>>       =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.co=
m>
>>>>> 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=
=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 differen=
ce
>>>>>           =20
> of
>   =20
>>>>> 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 inpu=
t
>>>>>           =20
> and
>   =20
>>>>> output, to provide a constant accurate impedance matching to keep t=
he
>>>>> 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:
>>>>>
>>>>>
>>>>>
>>>>>           =20
>>>       =20
> https://dl.dropbox.com/u/19882028/MF/473%20kHz%20ZF%20Filter%2040%20dB.=
png
>   =20
>>>
>>>       =20
>>>>>
>>>>>           =20
>>>>
>>>>         =20
>>>>> There should be a much better image rejection now and so maybe a fe=
w
>>>>> 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
>>
>>     =20
>
>   =20