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When I was a 7 year old kid, up until I was 18, I fished frequently during the summer.? I always used lead sinkers.? I also always crimped them on the fishing line with my teeth.? I also remember chewing on one of the sinkers on more than one occasion just because it was fun.

I have also have amalgam fillings in a few of my teeth.

I have also handled mercury from a broken old thermometer with my bare hands - because it is fun - and Mercurichrome was standard faire in our home when I was growing up; both the dab-on kind and the kind which came from a spray can.? I appreciate that Dad knew there was no antiseptic match to the product when applied to the newest scrape or cut which was obtained from being adventuresome children growing up in an amazing world without doomsayers around every corner warning us about the dangers of radiation from the Motorola color TV on which we watched Saturday morning cartoons or some other such nonsense.

This was also the time in my life when I became interested in electronics.? I loved the smell of the pine-based (or whatever it was made from) rosin in the 60/40 solders of that era.? I created many projects and desoldered many old boards for spare parts.? And I stripped tinned wires with my teeth.? In fact, I still sometimes hold the solder with my lips when I need a third hand while soldering things.

My last home had copper pipes with lead solder solidly holding it all together.? I raised two children in that home.? One is a brilliant biotech engineer who graduated in the top 1% of her class.? The other has an IQ as high as his old man had 30 years earlier.? They grew up in that same home where I soldered things on probably a weekly basis - and I never use lead free solder.

When I was a teenager, I worked in an auto shop which performed brake jobs and had a machine to grind new brake shoes to the proper size.? Those shoes and the dust they created contained asbestos.? Later on, I worked for a shop which installed and maintained industrial sound equipment.? Often times we were tasked with drilling holes in asbestos materials to run new audio wiring.? Then I worked at a radio station which had a transmitter that held within it PCB containing capacitors and transformers in an old building with asbestos ceiling tiles.? Later, I went to work for a TV station which had huge Klystron beam supply transformers which also contained the rectifier stack, all cooled with PCB-containing transformer oil.? I've often been up to my shoulders in that oil while reaching in to unhook and retrieve the rectifier module to replace the blown diodes... the worst part of which was the fact that there was always a stored charge on those components simply due to being in close vicinity to 36KV in that oil, even though every possible point which was reachable was already grounded out with the "chicken stick".? It was always an adventure to reach into that oil.

One would think nowadays I'd be a walking bag of cancer or a blathering fool given the paranoia surrounding [insert purportedly dangerous substance here] in our environment to which I have been exposed my entire life.? And while that can be debated by some, I'd instead let the IQ test I took in my adulthood and my current state of close-to-retirement-age old-fartdom speak for itself. I think the biggest hazard I have to worry about right now is all the Marlboros, Big Macs and Coca-Colas I have consumed over my lifetime.? Those?are indeed the scourge of this country, and I'm happy to say I more-or-less swore off them all almost 20 years ago - but I would never dream of limiting someone else's freedom to partake in those same things if they so choose.

I will admit, however, that I wasn't very smart in choosing to marry a very liberal thinking person who believed in most of these hoaxes perpetrated by those who have huge financial interests which would be greatly increased by the populous believing their stories.? Thankfully that mistake is far behind me and I learned a great deal from it.

I think people in California have much greater hazards to worry about than fumes from soldering.? And if it doesn't matter to you that things of this nature exist mostly to make people rich, go ahead and purchase the most expensive new fume hood setup you can find.? One that gives tons of CFM, purifies the exhaust with hyper-expensive filters which cause far greater environmental damage to manufacture and dispose of than it could ever avert.? ?If you so strongly believe this to be a problem, why would you settle for anything less?? To do anything less would be killing your family.? To do anything less would be hypocritical and bad for the state.? If you know in your heart that there is grave danger in soldering things, your choice is clear; extremely expensive filtration which is guaranteed to eliminate 100% of the contaminates, or ceasing to do that kind of work.? Also, be sure you register your home as a potentially disastrous environmental pollution source; I'm sure the CA ministry of environmental protection directorate would want to know.

I againmissed the plot you provided.
A lot fo confusion has arisen due to your use of 6pF and 60R without any inital reference.hey were determined.

I still suggest that the BNC T method is a good option for Jinxie to check the unknown probe (up to 350MHz) given the resources that she appears to have available. Unlesss you can suggest a different, practical alternative.

Robert.

?

Posts crossed agin, I'm doing other things.

The Tek example is a 10M 100MHz probe. That is not the same as the 10073C.

The parallel capacitance won't be a constant 12pF, it will fall slightly up at VHF and UHF.

No,
I've not measured a high impedance 'scope probe on a VNA (which is typically intended for 50R systems). I'm away from home on business so won't be doing so any time soon (I have a number of VNAs).

When HP / Agilent / Keysight say the probe input impedance is 2M2 in parallel with ~12pF I tend to belive them. I cannot see where you are getting a RESISTANCE of 60 Ohms from.

As it is close to the reactance of the "missing" 6pF on your simulation maybe it make little difference, but surely, lacking any other data your simulation should use the published 2M2 in parallel with 12pF values for the 10073C?

Robert.

Crossed with Raymonds reply.

But you have Rp and 7pF probe capacitance.
That is counting the input capacitance twice.

Crossed with Raymonds reply.
I was assuming the probe input capacitance was 12pF. Seems odd to split the reactive impedance.

Robert.

My had both, but I concluded that the big one (HP-67 style) was not used, so I changed only that on board and it works.

Hi Gianni,

I'm one of the many that have admired your beautiful books from the beginning but haven't posted about that.

As regards your above post, I'm not sure what you mean by "both": Two NiCds? BTW, the HP-67 also uses the smaller 3-cell (HP-35 style) battery, the HP-97 (and HP-91) use the bigger, 4-cell type.

Raymond