Blank RF Probe tips

One of the kits linked in this thread, uses cpvc plumbing pipe, but they cover it with adhesive copper foil. Thats a good idea. They have some special caps on the ends, but I dont see why the pvc caps made for that pipe would not work. Glue on the front one, leave the read one loose. or put a little tape on it.

Copper plumbing pipe would make a good shell too, and the rear cap could be a copper pipe cap with a rubber grommet drilled in (for the wire), but I have not figured out what to use on the front that is non-conductive, and still strong enough for the probe tip.

I was looking at some of the old Eico probes. I used to have some of them (I wish I would have kept that stuff). There were 5 of them, all color coded. Yellow was direct, blue was RF, Green was demodulator, red was low capacity, and there was one more but I have not found pictures of that one, or what it did.

Anyhow, I have a direct one, just coax with a regular probe on the center lead and an aligator clip on the shield. But I want to make a RF probe. I dont really see a need for a demodulator, or low capacity, but I may in the future, now that I picked up a scope.

Funny how the "freedom of speech" usually only applies to the person claiming it.

I have a similar freedom, calling out people for being ignorant assholes when they wish to publicly display it.

On truth and democracy: There is a cult of ignorance in the United States, and there always has been. The strain of anti-intellectualism has been a constant thread winding its way through our political and cultural life, nurtured by the false notion that democracy means that "my ignorance is just as good as your knowledge."

ISAAC ASIMOV, "A Cult of Ignorance", Newsweek, Jan. 21, 1980

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Jeff-1.0 
wa6fwi 
http://www.foxsmercantile.com

As we are quoting fairly a learned writer, and one who also wrote a great d eal of science fiction, here is an equally appropriate quote from another l earned writer, who also wrote science fiction:

"You are not entitled to your opinion. You are entitled to your informed op inion. Nobody is entitled to be ignorant."

Harlan Ellison

Democracy arises only from exceeding wealth readily shared at every level o f society. And even a brief look at other so-called democracies in this wor ld, starting with India, and that obvious reality becomes clear. The United States is 21 (of 76) on a world scale, between Japan and Italy - both very recent converts to the title of 'democracy' on a world scale. A pretty sad condition for a so-called Beacon.

And to the extent that we fail to protect our least able citizens and resid ents, that is the extent to which we fail as a democracy. To the extent tha t we fail to educate our young to live, play, work and grow on the *WORLD S TAGE* is the extent to which we fail as a nation to grow and participate in that world stage. We cannot go it alone - hell, we do not even make one si ngle simple LDC screen in this country. We are a net-importer of agricultur al goods (due, in large part, to the consumption of illicit pharmaceuticals ), we cannot meet any of our most basic requirements from steel to energy t o minerals to necessary pharmaceuticals to much of anything else solely fro m domestic sources - NOR CAN THE REST OF THE WORLD FOR THEMSELVES, EITHER.

So, we are necessary participants whether we recognize it or not. Best to l earn about all this and understand it, rather than be caught blindsided by it, perhaps? We need to be smarter, harder working, faster, better educated , more thoughtful, less ignorant, cleaner and brighter than the rest of the world at every level of our society or we *will* fail. We need to make use of our incredible wealth, and not concentrate it into the hands of a very, very few - or we will lose all of it. We, the United States, are 5% of the world's population. Yet we consume just about 25% of the world's total res ources.

Ignorance will not protect that primacy. Nor will denying the consequences and necessities of that primacy. For us to live as we live, individuals in China, North Korea, Bangladesh, India, Pakistan, Congo, Sudan, Yemen, Somal ia, Haiti et.al. *MUST* live as they do.

Stop whining about what you don't begin to understand, stop living by recei ved wisdom, and start to understand reality.

As we are quoting, here is another one:

?But you were always a good man of business, Jacob,' faltered Scroo ge, who now began to apply this to himself.

Business!' cried the Ghost, wringing its hands again. "Mankind was my busin ess; charity, mercy, forbearance, and benevolence, were, all, my business. The deals of my trade were but a drop of water in the comprehensive ocean o f my business!?

Charles Dickens

America is no greater than the least of us.

Peter Wieck Melrose Park, PA

He who yells the biggest, loudest, and longest, wins. These days, freedom of speech mostly means WikiLeaks and commercial advertising.

Let he who knows all cast the first complaint.

Yep. Just ask any voter for the names of their recently elected officials. Most can name the president, and that's all. At best, they remember the names, but not their associated office. In a way, that's probably a good thing because if the GUM (great unwashed masses) knew what was happening in government, we would have continuous rioting and revolution. Political ignorance might be a good thing.

Ignorance is worse in technical fields, and we're all to blame. As technical areas such as computahs and electronics grow, the number of buzzwords, acronyms, trade names, and calculations necessary to be considered knowledgeable also grows. Jump into this maze of technobabble, after an extended absence, and even the most intelligent person will appear to be quite ignorant. I've had that experience dealing with radiation, modern medicine, and cycling. I'm currently providing a splendid example by making a fool of myself in another newsgroup demonstrating my ignorance of lighting and optics. It's all part of my "Learn by Destroying" paradigm, which in this case, involves destroying my reputation. I'll survive. Would you call me an ignorant asshole for failing to instantly assimilate the accumulated wisdom of some 500 years of optics?

Part of the problem is that Mr Oldschool is not responding to suggestions and answers to his questions. He usually drifts off on another topic, as if all the effort people have put into answering his questions was of no importance. Failure to appreciate is a capital crime, and I certainly feel unappreciated as all my comments have not even been acknowledged. So, I'll offer one last suggestion before I give up.

The "classic RF probe" is a marginal and crude device that was long ago replaced by far better amplified probes. The "classic RF probe" quits at about 100MHz, has a rather lumpy frequency response, and will load down high impedance circuits. If you have volts of signal to work with in a tube device, it will work as expected. If you're working on a modern low voltage device, you'll have problems. What's better is a FET input RF probe, something like these, which can be built: If you must use tubes, I could probably design a cascode Nuvistor RF probe for the occasion.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Duly noted so your ego remains intact this time. ;-)

--
Jeff-1.0 
wa6fwi 
http://www.foxsmercantile.com

I beg to differ. I one did some work in a sausage factory (adjacent to feed lot) which caused me to loose my taste for sausage. Believe me, you do not want to know how sausage is made. If the public was properly informed, the entire sausage industry would collapse. Better ignorant than informed.

It's like that in many areas, where carnal knowledge of the internal workings and operations can be seriously repulsive. If you knew the details of the private lives of historical figures, public personalities, politicians, and actors, you would probably be disappointed. Just meeting some of these in person can produce a similar reaction. Better to believe the myth than to be disappointed by the truth.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Thanks. It's rather difficult to be diplomatic and insulting simultaneously. I'm sure you're now planning how to retaliate.

Nope. That's an RF amplifier. I went looking for an RF probe schematic based on a Nuvistor, but couldn't find anything. There are some TEK oscilloscope front end circuits that use a Nuvistor, that could probably be converted into something useful. Basically, one needs a broadband impedance converter. Cascode (common emitter driving a common base) design seems right. It would take two 6CW4 Nuvistors, a length of 3/4" copper pipe, and some high voltage. If that's to messy, a single tube in a cathode follower derangement should work. It might get warm enough to be uncomfortable, but that's the price we pay for working with tubes.

Nuvistors are cheap on eBay but sockets are pricy: Hmmm... LTSpice models available for various Nuvistors. Never mind. I don't need yet another project.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Oh, I dunno. I am of the belief that one should not engage in an activity u nless one is willing to engage in the necessary and enabling first steps at some level more than theoretical.

Eat chicken much? Learn to kill, gut and pluck. Eat meat much? Eat fish much?

True, this society has gotten so far from the 'squeal' end of the process t hat those enjoying the bacon rarely have a clue. But it is that 'squeal' wh ere reality starts in, and the moment that end-user loses the connection en tirely, we are done as a society.

There is a working organic farm not far from our summer house run by a very hard-working couple who are also friends of ours. We have learned a great deal from them. But, until one is willing to put a bullet in the steer's br ain, hoist it (no longer 'him') up on a pulley, gut, clean, skin, and butch er it, it is too abstract to be real. We have canine teeth for a reason, an d we produce protein busting enzymes in our saliva for a reason. We need th e intellectual as well as intestinal fortitude to live with the connections .

Having made sausage - I have no problems with the process.

The difference between ham and eggs?

The chicken is involved. The pig is committed.

I always found the AC probe on the HP 410B to be great. But that uses a tube, a rectifier, right in the probe.

But you're probably right. A buffer would help, right where it's needed. And probably wasn't common in the old days because of cost, or getting a small tube in the probe. Or hobbyists never gave it much thought. SInce a lot of this is about relative voltage, or tuning for peak, having a flat buffer isn't even necessary.

Michael

For the record, I was ready to buy that kit from qrpkits.com, but found out they do not recommend it for over 50V. I emailed the vendor and asked if it could be upgraded for tube circuits. He told me that he can not recommend that, because it could be a shock hazzard. Although I do feel competent to make such a modification, I knew that would mean spending more money, and wasting more time to build a usable probe. Instead, I found a semi over priced old Eico RF probe (blue one) on Ebay, and just paid the price. As soon as it comes, I'll be all set....

I never heard of using a nuvistor in a probe, but I am sure it's possible. Seems kind of senseless though, when a simple diode along with a few other parts will do the trick. Just because I prefer to work on tubes, dont mean I wont use semi-conductors. For audio, tubes have a superior sound. For my abilities and test gear, I'll take tubes any day to work on. But I also do not mind working on older devices that contain transistors, such as my XAM amp. It's the devices that contain IC chips I detest. I'm not saying they are bad, and I am well aware my computer and a lot of other stuff contain them. But I strongly dislike working on that stuff. That was the main reason I stopped electronics in the late

70's as a hobby, and even more so as a repair business. It's not just the fact that the stuff is very hard to work on, but also that parts are far too hard to get.

As far as all thge political discussions that evolved in this thread, I have no further comments. I hate politics. However, I know it all began when I made a comment about todays youth being fat and lazy. That is my opinion, and I see it all the time. Some of my very good friends have kids who are now in their 20's and even their parents (my friends) say the same thing. I see it all the time. That dont mean I am right, it's just my opinion, buty I have a right to my opinion, and to express it based on my "freedom of speech" as well as just saying what I feel. Then again, there are a few exceptions. I know one young man who is a very hard worker and he has a good head on his shoulders. But he is one in

100 or 1000. Most of today's youth have no goals. They spend their time staring at their cellphones, work as little as possible (or not at all), and eat as much as they can cram down their throats, and it shows!

However, none of that has anytrhing to do with the topic of this newsgroup, aside from the fact that I would likely win a bet if I said that no one on this group is under the age of 45. Today's youth dont care to do electronics as a hobby. Nor do they care to do much of anything that involves using their brains or muscles. But I am not gonna join them. They can sit in their fancy restaurants and bars spending their parents money, and talking on a cellphone to the person sitting next to them. None of which makes any sense to me...... I'm just glad I was born in the 50's when life still had meaning. My only complaint about being born at that time is all the aches and pains I feel now! Getting old sucks! But I doubt I need to explain that to any of you old farts :)

If so, their parents are responsible, and we are either the parents or responsible for them.

Making us 100% responsible for the state of our youth - good, bad or indifferent.

Writing for myself, I am quietly proud of our kids, their kids and what eacn and ever one of them is doing with their lives - from second grade to senior partner. Not a fat one or a lazy one in the bunch.

Pretty much true of nephews, nieces and more.

A little bit of education does appear to help, however.

Peter Wieck Melrose Park, PA

I fully agree about the parents. But these days, you cant lift a finger or you'll be charged with abuse. An old spanking stick still has it's place. I know I got that stick several times and it was far from abuse. It just made me think....

But it does go beyond the parents. There is a lot to blame on the schools. From what I hear, most of them no longer have shop classes or anything like that. Heck, when I was in HS, I took every shop class they had. Wood shop, metal shop, motor shop, electronics shop, and more.... but I guess that stuff is "too dangerous" for kids these days. So, instead of cutting off a finger on a table saw, the kids lose their limbs from diabetes due to their obesity.... Or lose their lives from drug abuse because they are so damn bored....

I never had any children, so I cant brag about them.... Glad yours turned out good! But I will brag that my four legged kids are really good! (And I do have a REAL kid, a pet goat) :)

All whiny Blather Snipped.

It comes down to the parents - 100% and without reservation. Schools, from pre-school to graduate school are mines, knowledge is extracted from them w ith effort, time and concentration. They do not "impart" knowledge at any l evel. And, the ore exists even in the poorest schools. It really does. Been there.

If parents prepare their children in that extraction process, they will lea rn. If the parents do not, they will not.

Shop Classes: That is a matter of community values. Shop classes require a dedicated staff, expensive tools, space and maintenance. If the community v alues the product of these classes, they will happen. It's called Taxes.

We pay very nearly $10,000/year in dedicated school taxes. It will be 2042 before we pay back the system for the education extracted by our two, even at that rate. And right now, we are investing in the next generation of kid s and insuring that they have the same basic opportunities as ours did. A v ery simple concept.

Get over yourself. This is not an external problem. It is internal to all o f us - what are our values? Are they essentially selfish? I have mine! Or a re they focused on providing and supporting a community that will, in turn support us and our values into the future? I am 100% responsible for my con dition in life, and good or bad, that is the way it is. There is no one to blame, nothing has been taken from me that I was unwilling to give, nor has anything been given to me other than opportunity. That is the difference b etween a democracy - and anything else. Ours, by the way, is threatened.

And, to twist the knife a little - neither of my parents spoke English as t heir first language. But despite all that, they provided me with infinite o pportunity, and infinite support, and were excellent examples on how to wor k it out.

I have written this before, but sometimes the first application of the clue

-stick does not take:

Keep in mind that the Average American:

Does not have a college education, including an Associate Degree (60%). Does not have a passport (64%). Speaks one language ? badly (74%). Has never traveled voluntarily more than 200 miles from his/her birthplace (57%). Has never visited a foreign country, not even Mexico or Canada (71%). Cannot name the Speaker of the House, even today (82%) Cannot name the three branches of government (64%) Cannot read at a college level (83%) Cannot read for content (54%). This person cannot follow written-only direc tions.

60% of American Households do not buy any book in a year. Does not believe in Evolution (42% creationism, 32% evolution, 26% no opini on). Only 71.2% of eligible voters are registered. Only 57.9% of registered voters voted in 2012. Meaning that the average American eligible to vote does not vote (only 41.5 % net). Not much changed in early statistics for 2016, although the change was to greater participation (44%). The Average American still does not vo te.

This has not one damned thing to do with party, democrat, republican, liber tarian, communist, green, whatever. It has to do with massive, systemic and deliberate neglect, and industrial-grade stupidity mixed equally with mil. Spec. ignorance.

Quit your bitching - and work it out. It really is you, so only you can cha nge it.

Peter Wieck Melrose Park, PA

There's silica, silly and silly puddy, too.

That was sold. Here is a Heathkit probe:

Some of the old construction projects used aluminum cigar tubes, which can be found on Ebay.

I use a Boonton 9200 Digital RF millivoltmeter. The probe has a pair of diode, which are fed into a chopper circuit. It is good, past 800 MHz and it has a very low input capacitance. A divide by 100 capacitive divider/attenuator is also available. I have a couple of the older Boonton 92 series analog meters, as well

--
Never piss off an Engineer! 

They don't get mad. 

They don't get even. 

They go for over unity! ;-)