Date: Mon, 15 Jun 2009 16:02:48 +0200
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
From: Rik Strobbe <rik.strobbe@fys.kuleuven.be>
In-Reply-To: <002301c9edbf$1616cfe0$0900a8c0@AM>
References: <4A364395.9010201@telenet.be>
 <20090615131045.7B4E131E702@smtps01.kuleuven.be>
 <002301c9edbf$1616cfe0$0900a8c0@AM>
Mime-Version: 1.0
Message-Id: <20090615140241.DC2C0F3862@smtps02.kuleuven.be>
Subject: Re: LF: 500 kHz resonators at nedis.com
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


Hello Alan,

thanks for the info.
What I had in mind was a 501-504kHz filter so not=20
as narrow as the 800Hz filter you designed.
And as an input filter I wouldn't care about 10dB=20
(or even more) insertion loss as I always have a=20
20dB attenuator between antenna and RX.

73, Rik  ON7YD - OR7T

At 15:38 15/06/2009, you wrote:
>Hi Rick there is a problem building a sharp ladder filter with 500 or 455
>kHz resonators. I have played with a number. the difficulty seems to stem
>from the fact that to get a narow filter you have to design for a filter
>impedance of around 250 to 300ohms. then when you conside the ESR of the
>resonators of say 40 to 70 ohms and 5 in series you have a lot of loss
>through the filter. The best I managed at 455khz was about 800Hz pass band,
>but a lot of insertion loss. I think a more promising format is to use the
>resonators in shunt (parrallel resonance) with top coupling. I think the
>late Jan Noedling  LA2AK had some information on his web pages which I
>believe are still available. I have not tried that yet.
>
>Rapid Electronics does wire ended ceramic resonators for between 10p and 20=
p
>(exVAT)each in singles and discounts lots of 25  by a further 10% or more.
>No Min order but =A33 postage on oders less that =A330
>www.rapidonline.com
>Best Wishes
>Alan G3NYK
>
>
>----- Original Message -----
>From: "Rik Strobbe" <rik.strobbe@fys.kuleuven.be>
>To: <rsgb_lf_group@blacksheep.org>
>Sent: Monday, June 15, 2009 2:10 PM
>Subject: Re: LF: 500 kHz resonators at nedis.com
>
>
> > Pedro,
> >
> > I have a VXO with a 4MHz ceramic resonator. That signal is divided by
> > 8. Range is 500.5 - 506kHz.
> > see
> > http://wireless.org.uk/500k_tx.gif
> > http://wireless.org.uk/qtx.htm
> >
> > 4MHz cer. resonators are available at less than 1 Euro in almost
> > every electronic shop.
> >
> > 500kHz cer. resonators however could be interesting to build a sharp
> > RX-input filter (cfr xtal ladder filter)
> >
> > 73, Rik  ON7YD - OR7T
> >
> >
> > At 14:50 15/06/2009, you wrote:
> > >Hello group,
> > >
> > >I just discovered that the European grossist for electronic parts has
> > >500 kc ceramic resonators in their range for less than half a Euro.
> > >this is a great building block for a tunable 500 kHz transmitter.  I
> > >ordered some for test purposes to see how far they can e pulled.
> > >Unfortunately they don't sell direct to customers, only to retailers.
> > >
> > >
> > >Pedro
> > >
> > >www.nedis.com
> >
> >