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Message-ID: <002f01c9edce$0bdc4280$0900a8c0@AM>
From: "Alan Melia" <alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
References: <4A364395.9010201@telenet.be> <20090615131045.7B4E131E702@smtps01.kuleuven.be> <002301c9edbf$1616cfe0$0900a8c0@AM> <20090615140241.DC2C0F3862@smtps02.kuleuven.be>
Date: Mon, 15 Jun 2009 16:09:40 +0100
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Subject: Re: LF: 500 kHz resonators at nedis.com
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Hi Rik that would work quite well, there were some parameters for the
resonators at 4MHz discussed on the emrfd group recently. The parameter
measurement methosd are the same, but they were using the resonators for
"VXOs".

 I used measurements suggested by Jack Harcastle GJIR. If you are designing
for a 3 to 4kHz BW then you could aim at a much higher filter impedance
which makes it all a bit easier.

Alan G3NYK
----- Original Message -----
From: "Rik Strobbe" <rik.strobbe@fys.kuleuven.be>
To: <rsgb_lf_group@blacksheep.org>
Sent: Monday, June 15, 2009 3:02 PM
Subject: Re: LF: 500 kHz resonators at nedis.com


Hello Alan,

thanks for the info.
What I had in mind was a 501-504kHz filter so not
as narrow as the 800Hz filter you designed.
And as an input filter I wouldn't care about 10dB
(or even more) insertion loss as I always have a
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
20p
>(exVAT)each in singles and discounts lots of 25  by a further 10% or more.
>No Min order but Ł3 postage on oders less that Ł30
>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
> >
> >