[MAMS] 47 GHz

[Zack Widup]

If I had to drive 23 miles I might have considered McMaster-Carr. As it
was, I only had to drive a half mile.
:-)

Also, I have been told by several people that WR-34 and WR-42 can be butted
up against each other with virtually no loss at 24 GHz. They are both the
same height and the waveguide flanges use the same hole spacings.

I had a course in engineering probability taught by an EE professor who
taught the course because he wanted to learn more about it! It was an
interesting course. He was learning along with the rest of us.

73, Zack W9SZ


On Mon, Oct 31, 2011 at 11:51 AM, Dr. Gerald N. Johnson <geraldj at weather.net
> wrote:

> Sometimes its more productive to order and get next day delivery than to
> drive 23 miles one way to the nearest hardware store, then hobby stores,
> that carry K&S to find them out of stock. Though the delivery costs from
> McMaster are higher this year than they used to be.
>
> So long as the ratio of width to heights are the same different sizes of
> wave guide can be butted without a serious mismatch. The Z0 is based on
> the ratio of height to width. The junction will impose a lumped C across
> the guide that usually isn't all that bad a mismatch.
>
> Must tell a tale.
>
> Iook a senior/grad Fields Course as a beginning master's candidate.
> About half seniors and half grad students. It was taught by a professor
> experienced in physical chemistry, but not electrical engineering. He
> thought since it was based mostly on 3D tensor analysis that he knew
> enough of that. It was a 4 quarter course, I have notes from the first
> quarter, but none after that. It proved that he was reading enough per
> class day to build a lecture on expanding the math but had never read
> the book to the end. One day after spending about a week developing the
> relations for a step in a waveguide height, one student named Charlie
> Sie spoke and asked, "Professor K...., what's this good for?" Professor
> K.... looked at me and knew I had industry experience and said,
> "Johnson, what's this good for?" Rather that coming off the top of my
> head knowing it made a mismatch from the capacitance across the guide
> and was also used as an element in making filters, I had read ahead in
> the book and quickly thumbed back to the filter chapter and said, "Back
> on page 455, our book author (R. F. Harrington) uses them to make
> filters." The professor looked like I'd inserted a knife between his
> ribs and twisted it. He deserved it.
>
> Charlie went to Ovonics in Michigan, a pioneer in polycrystaline solar
> cells. I got drafted. The professor continued muddling his way through
> courses he didn't know anything about.
>
> 73, Jerry, K0CQ
>
> On 10/31/2011 10:11 AM, Zack Widup wrote:
> > Yeah, I looked at their selection. For my purposes 1 foot of the
> > rectangular bras tubing was plenty. I did get the aluminum stock from
> > McMaster-Carr and it was delivered the day after I ordered it.
> >
> > Probably for the circular waveguide the nearest English unit size of
> brass
> > tubing (also available in most of the hardware stores around here) will
> do.
> > Since these transverters I'm making are one-up assemblies and don't have
> to
> > mate with anything commercial, they should do fine. One of the joys of
> ham
> > radio.
> >
> > 73, Zack W9SZ
> >
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