Re: BAW

On Sat, 25 Jan 2025 19:36:19 +0000, Cursitor Doom <cd@notformail.com>
wrote:

On Sat, 25 Jan 2025 09:05:42 -0800, john larkin <JL@gct.com> wrote:
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On Sat, 25 Jan 2025 13:55:05 +0000, Cursitor Doom <cd@notformail.com>
wrote:
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On Fri, 24 Jan 2025 17:46:24 -0800, john larkin <JL@gct.com> wrote:
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On Sat, 25 Jan 2025 00:41:39 +0000, Cursitor Doom <cd@notformail.com>
wrote:
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On Wed, 22 Jan 2025 17:09:29 -0800, john larkin <jl@glen--canyon.com>
wrote:
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On Thu, 23 Jan 2025 00:55:25 +0000, Cursitor Doom <cd@notformail.com>
wrote:
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On Wed, 22 Jan 2025 10:55:39 -0800, john larkin <jl@glen--canyon.com>
wrote:
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On Wed, 22 Jan 2025 18:07:06 +0000, Cursitor Doom <cd@notformail.com>
wrote:
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On Mon, 20 Jan 2025 16:26:10 -0800, john larkin <JL@gct.com> wrote:
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On Mon, 20 Jan 2025 19:52:03 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
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john larkin <jl@glen--canyon.com> wrote:

https://www.ti.com/product/CDC6C
 
These are like 35 cents at 1K.
 
 

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Of course a crystal oscillator is a BAW device too. ;)
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Cheers
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Phil Hobbs

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Don't get technical with me!
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I wonder if it's all silicon, a sort of bulk MEMS thing. The price is
absurd. I guess every one has to be trimmed to frequency.

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Phil's pretty good in that regard. There are some people who see
everything in terms of equations and use higher mathematics to explain
their function. A xtal oscillator would provide a very simple example
for such persons to exhibit this (most unfortunate) character trait.

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Phil is one of those people who can see equations in motion. I can't.
I operate on instinct and simulation.
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We have brainstormed on some pretty important projects and generated
some ideas that influence most everyone here. The skills are
complementary.
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His book is good to have if you design electro-optics or low-level
analog stuff.
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https://www.amazon.com/Building-Electro-Optical-Systems-Making-Applied/dp/1119438977/ref=sr_1_fkmr0_1?crid=3M9PG1T68443R&dib=eyJ2IjoiMSJ9.xIlGO_AWviZZRYMlHFKJuNzKnLc8MDBpUjgE7RsYsDk.WiFCuc8GjBlGtPimMCFx0kOu5NieBv0TzXDNCokyLQM&dib_tag=se&keywords=phil+hobbs+optics&qid=1737571796&s=books&sprefix=phil+hobbs+optics%2Cstripbooks%2C138&sr=1-1-fkmr0
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Be cautioned that there are equations.

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Equations are fine (unavoidable anyway) in this science. But it's not
helpful in the first instance to gain an intuitive idea of how
something works - unless you're one of the people I mentioned above.
This is my main issue with Tom Lee's otherwise superb book, 'Planar
Microwave Engineering' where he typically launches into higher
mathematics almost from the get-go.

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I have that book. It's mostly useless. One equation will be a full
page of fine print, and then the next page turns out to be one term of
that equation.

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Indeed. Not only that, but the mathematics is unfamiliar. I know most
of the equations for transmission line theory by sight, but the ones
Tom cites are completely different and tend to use a lot of Greek
letters which relate to physical constants I've never even heard of.
On the other hand, where he doesn't use unfamiliar mathematics,
there's a *lot* in there I haven't seen any any other RF books which I
find really interesting.

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It's easier to design with a geometry for which there are good
calculator programs.
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We have used ATLC to do e/m simulations of transmission line cases.
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https://www.dropbox.com/scl/fi/6kdejmbybk4u5mq1xjait/Edge_alone_4.jpg?rlkey=volom4afazo44o6cpedgl89ge&raw=1
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https://www.dropbox.com/scl/fi/82ysq5m13br8ahubdi4z7/Rob1.jpg?rlkey=4bnm3uu5otfolka9gqsov5tel&raw=1
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https://www.dropbox.com/scl/fi/ogfqs1m93mf1uw80hwkpi/Rob_51_ohms.jpg?rlkey=u4q3fumbzwmpojck5ih88c45q&raw=1
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That one butchers a multilayer PCB stack to get a good match with a
cheap edge-launch SMA connector.
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https://www.dropbox.com/scl/fi/n7hlatrxdoiywfkvebqj9/DSC01527.JPG?rlkey=hycib2nrk4zv662mu5vndy23g&raw=1
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I had to google ATLC simulator as I've not heard of it before. Anyway,
these plots are all very interesting, but you have no way of verifying
their accuracy AFAICS.
You mentioned a while ago you had a good source for cheap but
reasonable quality edge connectors (Aliexpress?) Can you post a link
to them please?

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ATLC2 is a bit easier to drive.
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The way to verify a sim is to make a board and TDR it. They are
usually close.
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The one in the pic above is from Shining Star.
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SHINING STAR        19521000
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We use
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SHINING STAR        24521116
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too, a bit longer part. Both about $1.90.
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I've bought a bunch of similar ones from Amazon and they have been
great. But it's our general policy to not use Amazon parts in
production.
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Here's a 4-layer proto board that let us TDR the connectors and the
relay.
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https://www.dropbox.com/scl/fi/bvcnqnvb4euc7pqw7wzab/DSC06884.JPG?rlkey=q1op81z1bumkfxoq8d5mtzi91&raw=1
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Forgot to mention (and sorry if I've asked you this before but you
have to allow me some extra forbearance on account of my age) - what
do you use for your TDR?

I have an ancient Tek 11802 with an SD24 TDR plugin.