Tek P6007 for measuring -3kV 25kHz square wave - suitable or not?

[Lorenzo_1]

I'm thinking about getting a Tek P6007 probe for the infrequent but important task of testing the -3kV supply output on my Tek485.  I have a 1000x multimeter probe rated to 40kV DC or 20kVAC but it's only it's only AC rated to 60Hz.  The HV input to the multiplier is a 25kHz square wave and the schematic indicates the DC level is 0V, so with +/-1.5kV levels. I can't see the 1000x multimeter probe giving any sort of meaningful reading at 25kHz.

The P6007 is rated to 4.2kV AC p-p with derating curves as attached.  I think this should be suitable for this task. I'd appreciate advice from experts here as to whether I'm missing something important and whether this will do the job safely.  Only time I've measured it previously was with an expensive borrowed HV probe not accessible now.

Probe manual's accessible here  -   http://bama.edebris.com/manuals/tek/p6007/

[HighVoltage]

As long as this P6007 is in good condition, it will work for this task.

But, be careful, I have seen P6007 probes that have gotten micro cracks over the years and then they are not safe anymore.

[Lorenzo_1]

Thks for the confirmation - I think I'll kick this along.  I'm pretty sure I came across some reasonably priced new/replacement probe bodies for this unit when scouring the interweb.

[texaspyro]

Somewhere I have a Tek high voltage probe (don't remember the part number), but to use it at its rated voltage you have to fill it with a liquid fluorocarbon.  At the time it was several hundred dollars a pound... I don't think you can even legally buy the stuff now.

[HighVoltage]

Somewhere I have a Tek high voltage probe (don't remember the part number), but to use it at its rated voltage you have to fill it with a liquid fluorocarbon.  At the time it was several hundred dollars a pound... I don't think you can even legally buy the stuff now.

The TEK probe you are referring to is the P6015, that required to be filled with a liquid insulator.
The successor is called the P6015A and it is filled with a silicone gel that does not need to be replaced.

[Lorenzo_1]

I've looked at the 6015 and 6015A but wouldn't use it enough to be worth the price. Hence my query re the P6007 for occasional HV use. The one I used some years ago was similar in design/bulk to the 6015/A, so wasn't sure about the much smaller P6007, despite the 4.2kV AC rating.

[texaspyro]

The TEK probe you are referring to is the P6015, that required to be filled with a liquid insulator.
The successor is called the P6015A and it is filled with a silicone gel that does not need to be replaced.

Yep,  that's the one.   There is a listing on Ebay for a refill service for $60.   There is also a listing for a defective probe... that comes with a can for the fluid for around the same price... no telling if the can has anything in it.

[HighVoltage]

I do have several of the P6015A with silicone gel filled insulator and they work great but they are limited to 40 kV max. If this one breaks, it can not be repaired.

If I need to go a little higher in voltage, I am using the older P6015 that can be used up to 60kV for a short time (not documented) when filled correctly with the dielectric filling. This one can be repaired and refilled, if needed.

Another older and good probe to look for is the Tektronix P6009 for up to 2 kV





 

[alm]

The derating curve is for a 3.5 feet cable. Is that the version you have? I believe either the 6 or 9 feet version was the most common.

The input voltage is limited to 1.5 kV DC or RMS. In good physical condition, it should be fine for a square wave up to +/- 1.5 kV. So it should be barely sufficient assuming there is no DC offset. Based on the derating curve, I would not be too worried about the odd harmonics produced by the square wave. The energy should be well below the ~5 MHz where the derating curve drops below 3 kV_p-p.

[Lorenzo_1]

Good advice - thanks everyone. There's no DC offset for the test I asked about, so should be OK, but I'd overlooked lead length issue. Something to look out for. Is there a rule of thumb for derating for lead length- doesn't seem likely, but I don't recall seeing anything in the probe manual. Will also look at P6009 as alternative. I've not seen P6015/A at prices that make sense for my limited uses.

Also good to be aware P6015A is non-repairable - not that I'd be inclined to get adventurous with HV gear. Many years ago I got a nice bite when testing ignition coils on a big outboard - numbed my whole arm for a minute or so and gave me a healthy and long-lasting respect for such things. Bit different from old-style motorbike coils. One of the hazards of working in remote areas and having to fix everything yourself!

[alm]

The P6007 manual has different derating curves for 3.5 ft, 6 ft, 9 ft and 12 ft cables.