RF Circuit Design - Chris Bowick

Reading about how they work and what they can do. Dig through the spec sheets and look at the applications notes. Skim the online catalogs to see what's available. Search Google of articles and photos of what others have done. Reverse engineer competitors products if available. Beg vendors for free samples. Somewhere along the line of such an investigation, some product ideas might pop into your head.

I do, but it's 1970's and 1980's vintage equipment. You can do quite a bit with old test equipment. Same with the easily affordable "toy" test equipment that is appearing for sale online.

I don't use an oscilloscope for RF over about 75 MHz. I do have a sampling plugin (that needs some repair) but a scope only gets you so far. My major test equipment for RF are:

  1. Spectrum analyzer with tracking generator and lots of plugins.
  2. Sweep generator, with lots of plugins.
  3. RF signal generator.
  4. Broadband noise source.
  5. Frequency counter with lots of plugins.
  6. Return loss bridge, single port VNA, or antenna analyzer.
  7. Dummy loads, attenuators, power dividers, directional couplers, tunable notch filters, coax adapters, patch cables, crimping tools, TDR for testing cables, calibrated loads, etc.
  8. RLC bridge.
  9. Laptop computah with as much design and calculation software I can steal err... find.
  10. Communications service monitor (optional) for NBFM work.

In the not so distant past, the shopping list for such equipment would be in the tens of thousands of dollars. Today, you can probably buy everything you need for working up to 2.5GHz for under $2,000 USD.

My $50 TinyVNA works to 1.5GHz, but is only accurate to about 100MHz. The Smith Chart display is useful for antennas.

Do you really need to fix it if the lower ranges are working? What are you planning to do above 10GHz? Talk to satellites?

If you can't handle the GHz stuff, buy modules for the mm wave frequencies that downconvert to something you can handle.

Learn to scrounge. Much of my test equipment came from thrift shops, who didn't know what they had, and eBay (which can be overpriced). All of it required repairs (usually electrolytics and tantalums). I also inherited some equipment from several aging ham radio operators.

I'm 72. The hand is still steady but the eyesight is rapidly deteriorating. So, I bought some microscopes: My guess(tm) is have about $350 invested in *ALL* the microscopes pictured. The most expensive items were replacement and additional objective lenses and eyepieces. Something like this would be ideal: You can also get a microscope camera that fits in place of one of the eyepieces. I bought a cheap one and regret it. Buy one that has a

0.5x lens.

Well, I tried and methinks that you're hopeless.

I tend to judge people by their willingness and ability to learn. What you've done is essentially announce that you don't want to try anything new and prefer to dabble in what you find comfortable. I realize that you probably don't care, but you just failed my litmus test.

It's also difficult to know that you've arrived if you don't know where you're going. Good luck doing what you enjoy so much.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Jeff Liebermann
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I've a colleague who discovered a packrat (or some other sort of rodent) had managed to chew a portion of the texts that he'd stored in a shed (no basements, here). He only realized this after a leak in that shed's roof managed to soak several boxes of those texts! :-/

Of course, had they all been stored in digital form, he could have had limitless copies of the entire archive (cloud, safe deposit box, bookshelf in the living room, kitchen drawer, etc.).

And, he'd be far less likely to have to decide which titles to discard (for lack of dry, rodent-free storage space! :> )

[one thing you DON'T want to do is adopt a "closed" document format for electronic media lest you find yourself looking for a 30 year old MagiReader 2000 when YOURS s**ts the bed!]
Reply to
Don Y

That has already happened to me. When I dug out my Kindle DX Graphite: I tried to check if there were any pending messages or file transfers. It wouldn't connect via 3G wireless. At some time in the past, AT&T ended 3G service for Amazon Whispernet, leaving my Kindle DX unconnected. Since there's no SD card, ethernet or Wi-Fi in the Kindle DX, it's now useless. I checked an all my other Kindles still work via Wi-Fi.

Well, not totally useless. I noticed that I had downloaded the Kindle version of "Much Ado about Almost Nothing" by Hans Camenzind: So, I consumed the afternoon reading about half of the book. If you're interested in how the great men of electronics came to be, some funny, some tragic, and some rather oddly, this is the book to read.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Jeff Liebermann

MIT Radiation Lab Series

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Terman Radio Engineer's Handbook

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Radiotron Designer's Handbook

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--
Science teaches us to trust. - sw
Reply to
Steve Wilson

The Bell System Technical Journal (BSTJ)

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The Online Books Page

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--
Science teaches us to trust. - sw
Reply to
Steve Wilson

AEK has amassed quite a collection of scanned (hi-res) documents at bitsavers.org. One of my ToDo items is to forward my collection of MULTICS documents to him for inclusion in his archive.

[Also, several documents on early speech synthesizers that he appears to be missing]

Sure would be nice if there were 25 -- or even *35*! -- hours in each day!!!

Reply to
Don Y

That's pretty much my attitude too; it has stood me in good stead.

Such "I don't want to learn" attitudes are usually not confined to one area of a person's life. Based on CD's postings, his attitudes on other topics are congruent with that.

Reply to
Tom Gardner

My eyesight has always been bad, and isn't improving with age. My consolation is that the parts are so small now, nobody can work with them without optical assistance.

The EPC GaN fets are cheap and electrically fabulous, but they are BGAs, so take some effort to get used to. It's worth the effort.

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We made our own adapters.

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EPC has LT Spice models too. The idea here is that if you sim a few circuits, you'll be amazed and simply have to try them in real life.

One thing about learning something new, or about doing lots of other things, is just do it. Once you get started, it's not so bad.

--
John Larkin      Highland Technology, Inc 

The best designs are necessarily accidental.
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jlarkin

I've taken over finishing and final-tuning the PCB layout of a

10-layer board with about 1000 parts.

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OK, I'm a fogie, but it is so much easier for me to visualize the power planes if I print them out on paper.

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(my version of "Windows")

I add text to each pour region to ID the voltage. That makes it a lot easier to understand. There are arguably 33 different power rails on this board.

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I print the schematic too, all 31 pages of it, so I can read it in bed, or scribble on it.

Paper is amazing technology. I must have 100 colored pencils and pens.

--
John Larkin      Highland Technology, Inc 

The best designs are necessarily accidental.
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jlarkin

Rubbermaid bins are pretty cheap. I sure wouldn't store books in cardboard boxes in an outbuilding--just the mildew would be an issue.

Cheers

Phil Hobbs

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Dr Philip C D Hobbs 
Principal Consultant 
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Reply to
Phil Hobbs

It would probably be a futile and expensive thing to try, but I'll bet you could find the makings of a 3G base-station/test infrastructure that could let you create a local 3G access point, and bridge it into your home Ethernet.

Reply to
Dave Platt

You can't stack rubbermaid bins when they are loaded with ~80-120 pounds of books, each. By contrast, you can pack a nice, "square" box

*solid* and effectively turn it into a brick -- which stacks nicely atop other such bricks. Witness how well photocopier paper stacks.

By contrast, we can't stack the rubbermaid bins in which we store our bedsheets to cover the citrus trees without the bins deforming under the weight.

Reply to
Don Y

You forgot to chew the pencils... :)

Reply to
Sjouke Burry

Sure you can, as long as there isn't more than 1/4 inch or so of space between the lid and the top of the books. It does take a bit of care in packing them

By contrast, you can pack a nice, "square" box

Books are already bricks, unlike bedsheets.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
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Reply to
Phil Hobbs

Your Mo is a very patient woman. ;) (So's mine, actually.)

I'm not that far out there--I generally use only five or six colours.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
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Reply to
Phil Hobbs

*YOU* may be able to. But *I* find hefting large boxes of that weight range to be a bit too difficult! Especially if you have to, eventually, shuffle them around to gain access to a particular box (which will likely NOT be "on top").

When I moved here, my paperback collection came in ~80 boxes just a bit smaller than a box of photocopier paper. The ~18" length is just about ideal for lifting (distance between shoulders). And, the smaller size (wrt the large rubbermaid tubs) means there's less weight involved. Of course, paperbacks tend to share a common size (in at least two dimensions) so packing is less of an exercise than trying to fit arbitrary sized text books!

The large plastic containers are just too big -- especially if you need to fill them completely (to maintain their "stiffness" as well as reduce the volume that they require to store your goods). They're great for things like XMAS ornaments -- which are mostly air!

Bedsheets are *ideal* bricks! They can be tailored to any size/shape based on how they are folded. And, as they are standardized sizes, its easy to create multiple instances of a particular finished size by simply folding each sheet the same way.

And, while they aren't inherently rigid, you can "overpack" them into a container so that weight from above compresses them to the point where they are, effectively, bricks.

But, then you're back to big, heavy boxes, again!

As to mildew, water damage, etc. Garages and out-buildings are the ideal places to store items, here. It is REALLY dry -- unlike the miserable humidity, fog, drizzle, etc. you encounter up north. Tools left unprotected don't rust (unless left OUT in the rain). By contrast, I'd typically coat my tools with machine oil when I lived in less arid places.

Water damage is a problem in the interior of homes -- because there are so many roof penetrations in a typical home. E.g., we have:

- three soil stack vents (~2" dia ea)

- two combustion reliefs (~1 sq ft ea)

- evaporative cooler (~2 sq ft ea)

- power/control to evaporative cooler (2" dia ea)

- one water pipe (for cooler)

- three exhaust vents for bath/kitchen fans (6" dia ea)

- two exhaust vents for furnace and water heater (4-6" dia ea)

- two skylights

- six vents for the underside of the roof (~1 sq ft ea)

- three channels for antenna/phone wiring to interior walls (3/4" dia)

And this is a small house!

Leaks are almost NEVER in places other than the perimeters of these penetrations (if your roof, itself, leaks, it's a sign that you've ignored it for far too long!). The sun bakes the materials that are used to seal around them and the materials dry out, crack, separate, etc. Periodic inspection and a bit of effort makes it relatively easy to reseal these areas (cut out the old and replace with fresh)

If you don't aggressively maintain your roof, you WILL have a leak in your living space. Most of our neighbors have had such failures (whether they have flat or peaked roofs, rolled felt or asphalt shingle or ceramic tile).

[My other half chuckles when she visits many of her friends in their $1M+ homes during Monsoon -- and finds pails and sauce pans located around the house to capture water from leaks through the ceiling!]

Note that garages don't tend to have any of these penetrations in the roofs above them.

Nor do outbuildings/sheds.

So, no risk to the items stored in the garage or outbuildings, from above.

Of course, that assumes you are doing regular maintenance on the roof and not ignoring it because it's out of the way -- like my friend's case. But, he's got lots of structures on his sprawling property so its easy to see how he can lose track of each.

There is the possibility of driven rain entering these spaces at ground level -- under doors, etc. But, you can guard against that by placing items on metal channel instead of directly on the floor (lumber wicks water as well as inviting termites)

A slab under any such storage is essential as anything resting on the dirt will invite "critters" of various types. Drop a 2x4 on the ground and you'll quickly find it covered with a fine layer of dirt. Disturb the dirt and you'll find much of the 2x4 eaten away!

[LEAVES that are left on the ground are similarly coated with dirt!]

And, maintaining a gap between those items and the walls.

[Our local library had stored donated books in an interior storage room. The boxes were piled against the wall and left to accumulate for years. When we went through them to clean out the room, we found the lower boxes' contents EATEN by termites -- which had exploited a crack in the slab at the wall to gain protected entry to the cellulose.]

As no one has a basement, here -- and the few attic spaces suffer from low pitch rooflines -- EVERYONE stores items in their garage and one or more sheds (actually, we don't have a shed but we are more aggressive in managing our "surplus"). Most folks buy large (2-3 ft long) plastic storage bins and endeavor to stack these in their garage. They invariably lose their shape as RE-stacking them neatly becomes a chore, over time.

We have access to "endless" supplies of boxes from the local hospital. So, its easy to find a box that is the right size/shape for our needs. Then, collect *dozens* of them as the items that were shipped in them are invariably shipped to the hospital every week/month.

E.g., I have ~180 identical boxes (half the size of a copier paper box) stacked in the garage for things like "Hammers", "Chisels", "extension cords", "CCTV cameras", "water filters", "VHDCI SCSI cables", "CAT5 patch cords", "DVI cables", "HDMI cables", etc.

I have another ~100 identical boxes (shoebox sized) for things like "PC2 < 6400", "SIMMs", "PC3 > 12800", "SCSI terminators", "memory cards", "SSDs", "DVI/DP/VGA/HDMI adapters", etc.

Putting these things in store-bought plastic boxes -- which typically have some draft angle that complicates packing them side-by-side -- I'd not be able to store half of what I have crammed in there, presently! Or, would have to toss unrelated items into shared containers just to economize on volume. (cuz store-bought boxes come in a narrower range of sizes/shapes than cardboard boxes)

Reply to
Don Y

Jeff, I'm just not the least bit interested in those aspects of electronics. I'm one of the older/est posters here, I'll be dead pretty soon so I want to spend my sunset days doing what I'm interested in and enjoy - not something someone else who doesn't even know me thinks I should be doing! :-D

My willingness to learn new things is one of my defining character traits, Jeff. I *do* have other interests outside of electronics where I *do* push myself - in an attempt to ward off dementia as much as anything else! But those suggestions of yours? Sorry not my bag, baby. :-)

Reply to
Cursitor Doom

Yes, and there's increasingly less and less of it left. None of us are getting any younger and one approaches one's dotage, time spent doing what we enjoy becomes more and more precious.

Absolutely. I have so many interests I'm like one of those plate spinners you used to see on TV many years ago, trying to keep them all going.

I very much admire that lady's pluck, but taking up physics - and the math that goes with it - at 80 would be a stretch too far for me. I know my limitations. The thing is, I'm not particularly good at electronics and no matter how hard I worked, I'd never be in the same league as the Win Hills, the John Larkins, the Phil Hobbs and the Jim Thompsons. Fortunately I knew this quite early on so never went into the field professionally - thank god as I'd have been a no-mark and never would have amounted to anything. Electronics for me is just a great, life-long hobby and nothing more.

I fully agree. I just cannot understand the mentality of those who show no interest in the world and how it works. I can't imagine anything worse than just 'vegging out' in front of the TV all day. If that isn't inviting dementia I don't know what is. :-/

Reply to
Cursitor Doom

Still sore about that pulled job-offer, eh, Bill? I reckon John dodged a bullet with that decision.

Reply to
Cursitor Doom

Umm... that would be the worlds most expensive replacement for Wi-Fi. Nothing like building a personal cell site to keep me busy for the next year. It can probably be done. The Kindle DX 3G radio uses HSDPA with fallback to the older EDGE and GPRS. Such a base station has been successfully reverse engineered, including the encryption. For example:

A more practical way might be to find an AT&T 4G(LTE) data modem or smartphone that supports a USB 2.0 input for tethering. Something like this perhaps: However, I would need to purchase an AT&T SIM to activate it. Even if it connects to AT&T, there's no guarantee that it will be recognized by Amazon Whispernet.

It might also be possible to network the Kindle DX via the USB port by jailbreaking the Kindle DX and replacing some drivers. This article offers a clue:

Another possibility would be to replace the 3G radio card inside the Kindle DX with a more modern LTE radio card. Looks like a standard PCI-e cellular data card. See Fig 3:

However, Don Y had the right idea. Just plug transfer the files via USB from a PC. I don't get the benefits of being able to email documents to my Kindle DX, but as an alternative to hacking the Kindle DX, it's good enough.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Jeff Liebermann

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