Best 1MHz 1pF active probe for a plain old Tek 400MHz scope?

You can get the matching Tekprobe supplies on eBay. I have both the

The P6243s are ten times faster than your scope, which is a waste. You could attach them to the 1103 supply and run regular BNCs from there to your scope (in 50-ohm mode). I bought the 1103 so I could use P6243s with spectrum analyzers, which is sometimes useful, though their intermod performance probably isn't quite what you'd want for general use.

Cheers

Phil Hobbs

(You can see EOI's equipment list at

-- we specialize in top-of-the-line boat anchors. ;) )

Phil Hobbs wrote

That's a really good tip - many thanks.

Those power supplies look totally homemade. Tektronix Guernsey??? They must have been making them in somebody's spare garage :)

But, hey, I was wrong. I found this amazing piece

It just says 'Forbidden' when I try to access that site.

Jeroen Belleman

That's astonishing. They have just done that, in the last 24hrs.

See this

Works fine for me.

Cheers

Phil Hobbs

Works fine here (NL) .

I tried again. It works now. I'm a fan of old Tek equipment. Not so much of the newer stuff though.

Jeroen Belleman

What is amazing is their vertical integration. They even moulded their knobs. Well you have to make your own knobs, to achieve a specific look, I suppose. If you achieve the volume, you end up with high margins.

Now they do the high end stuff and a lot of rebadged chinese stuff.

That's a keeper. I'd like to visit the islands some day.

When the EU tariffs changed, Tek pulled out but didn't just abandon the people. They licensed some TDR stuff to a group that became Polar Instruments, which is still around.

Many PCB houses use Polar software and instruments for making controlled-impedance boards.

I have a few old scopes, 545s, a few 547s, a 7104, a couple of older ones. And boxes of plugins. Anybody need plugins?

HP was grey and stodgy; Tek was fun.

I saved a PDF of that site.

Amazing :)

I fly (GA, from the UK) to Guernsey regularly. 40 mins. Nice easy airport; not a common thing over here. If flying commercially you can get a flight from Southampton and possibly even (London) Gatwick.

That's interesting.

I suppose import duties were big in those days. Nowadays it tends to be just a few %. Quite funny we are discussing this today, on the day of the most significant general election since WW2 :)

I knew a UK electronics mfg set up on Guernsey many years ago and everybody was convinced it was just a tax dodge, to shift profits out there where you pay less corporation tax.

I found a manual for the 6201 probe

Must be IP blocking parts of Europe.

It works for me from one IP but not from another. A VPN to another IP (all these are in the UK) also works.

This is a fun book:

and there was a good fictional TV series about the German occupation.

We buy Rigol nowadays.

I do love my 11802. I'll miss it when it finally dies.

Seems like some of the MSO4000 boxes are pretty nice, though they're way too rich for my blood. (If I don't spend my equipment budget, I get to keep most of the money.) ;)

Cheers

Phil Hobbs

Phil Hobbs wrote

I saw this

At work we bought a Le Croy 3000 500MHz 4Gs/s and it blew up (motherboard died - probably a PC in there) within a year. I could have bought 3 of the Teks for the price of the LeCroy and I am sure we would get more life out of three of those than one LeCroy.

OTOH the LC has a nice big screen.

There is a huge value in used kit - if you buy quality.

A 1pf capacitor has the same impedance at 318 MHz as a 500 ohm resistor.

A 1.5 pf active probe is the same impedance at 212 MHz. Obviously the capacitor impedance decreases as the frequency increases, where the resistor impedance remains constant.

You can put a 450 ohm resistor at the tip of a small probe, and terminate the coax in 50 ohms. This gives a 10:1 divider with a frequency response well into the GHz. See

The resistive input dampens the ringing caused by the inductance of the probe ground, and the resistor does not cause intermod distortion. A small capacitor in series with the resistor allows monitoring voltages off ground.

Cheaper, faster, better.

Except that it screws up the bias.

Cheers

Phil Hobbs