[time-nuts] 10 MHz low pass filter

Orin Eman orin.eman at gmail.com
Thu Aug 9 19:47:02 UTC 2012


A little delayed, but here's a sweep to 500MHz:

https://picasaweb.google.com/lh/photo/-wJRN8e2ugrxVVtMxqYI49MTjNZETYmyPJy0liipFm0?feat=directlink

1.2 dB loss at 10MHz.  Something going on at 347MHz.

If I get chance, I'll do a sweep to 1GHz.

Orin, KJ7HQ.

On Wed, Jun 20, 2012 at 4:17 PM, Thomas S. Knutsen <la3pna at gmail.com> wrote:

> Based on that PCB, I want to see an sweep to at least 1GHz.
> The reason is that experience have shown that the inductance (perhaps 10nH)
> in series with C2 and C6 would damage the stop-band rejection at UHF.
>
> Used with an OXCO this would not matter, but the desire to make the
> ultimate filter is still there.
>
> Thomas.
>
> 2012/6/21 <lists at lazygranch.com>
>
> > If the output is buffered, there really shouldn't be a problem.
> >
> > Incidentally, I can crank out high order LCR filters all day just by
> > transforming prototypes out of Zverev. But it has been my experience at
> > even 10MHz the parasitics of the elements will throw off the design.
> >
> >
> > -----Original Message-----
> > From: Bob Camp <lists at rtty.us>
> > Sender: time-nuts-bounces at febo.com
> > Date: Wed, 20 Jun 2012 17:49:37
> > To: Discussion of precise time and frequency measurement<
> > time-nuts at febo.com>
> > Reply-To: Discussion of precise time and frequency measurement
> >        <time-nuts at febo.com>
> > Subject: Re: [time-nuts] 10 MHz low pass filter
> >
> > Hi
> >
> > That's a pretty high order filter. The output of most OCXO's already has
> a
> > filter on it. Combining two filters (especially high order ones) without
> > isolation between them is not a good idea. The resulting transfer
> function
> > will not be what you expect it to be….
> >
> > Bob
> >
> > On Jun 20, 2012, at 4:54 PM, Joseph Gray wrote:
> >
> > > I came across this filter design recently and thought I'd build a few.
> > >
> > > http://www.jwmeng.com/AppNote/AppNote003.html
> > >
> > > I was about to place a Mouser order when I came across someone selling
> > > filters, based on the above design.
> > >
> > >
> http://www.ebay.com/itm/10-MHz-filter-kit-for-tcxo-gps-pll-/110893777470
> > >
> > > The price with a board seemed low enough that I ordered a few. I'll
> > > let everyone know how they work out.
> > >
> > > Joe Gray
> > > W5JG
> > >
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