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

I see a load of Tek P6243 and similar probes but they all have a special BNC plug, fairly obviously to get power and config etc.

What is a good active probe which is self powered?

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

1101 and 1103 supplies. The older 1101 matches the P6201 900 MHz probes, which are better than good enough for your scope, and it cost $50. Your scope might have the matching power connectors already--they're three-pin LEMOs iirc.

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. ;) )

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Reply to
Phil Hobbs

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

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1956-1990. They even had a Miss Tektronix competition :)
Reply to
Peter

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

Jeroen Belleman

Reply to
Jeroen Belleman

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

Reply to
Postman Pat

See this

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Reply to
Postman Pat

Works fine for me.

Cheers

Phil Hobbs

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Reply to
Phil Hobbs

Works fine here (NL) .

Reply to
Sjouke Burry

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

Jeroen Belleman

Reply to
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.

Reply to
Postman Pat

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

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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.

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

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John Larkin         Highland Technology, Inc 

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Reply to
jlarkin

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.

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John Larkin         Highland Technology, Inc 

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Reply to
jlarkin

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

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and it would be easy to make the power supply, but I bought one from the US anyway (heavy shipping and then ~25% VAT and duty). Now looking for a probe in a good condition on Ebay but preferably not from the US due to the costs.

Reply to
Postman Pat

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.

Reply to
Postman Pat

This is a fun book:

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

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John Larkin         Highland Technology, Inc 

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Reply to
jlarkin

We buy Rigol nowadays.

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

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John Larkin         Highland Technology, Inc 

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Reply to
jlarkin

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

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Dr Philip C D Hobbs 
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Reply to
Phil Hobbs

Phil Hobbs wrote

I saw this

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which was originally a $15k+ scope, c. year 2001.

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.

Reply to
Peter

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

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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.

Reply to
Steve Wilson

Except that it screws up the bias.

Cheers

Phil Hobbs

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Reply to
Phil Hobbs

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