Re: Tek P6xxx probe reference question


 

Hi Greg,

Yes, for many years it was not clear what Tek was doing with their probes.

I think the 3.5mm and 2.5mm probes were an attempt to make it clear from their description how big the probe diameter is rather than using less descriptive terms like "miniature" and "sub-miniature".

I believe the 2.5mm and 3.5mm reference is to the probe's ground ring diameter. I am not near any probes that I can check at the moment so I might be wrong about this. I must admit I never checked this until now, but I can point you to much more information on their probes and how Tek ended up with so many different probes.

Over the years there was a lot of pressure to:
1) Reduce the size (diameter mostly) of the probes so they could get into tighter spaces.
2) Reduce the circuit loading (capacitance mostly) from the probes.
3) Optimize the probe performance by designing some probes for specific scopes.
4) Create specialty probes for things like wafer probing, measuring digital signals with a logic analyzer. A more common example of these would be the P6015 High Voltage Probe or the P6021 current probe.
5) Provide enough accessories for each probe that the probes were very versatile.

Things really got really complicated in the mid-1980s when there were so many different probes that it was hard to know which probes worked with which instruments. That is when Tek included a few pages in their catalogs that showed which probes were recommended for which instruments and which could be used (but were not optimal).

Finally Tek had to do something better and towards the latter 1980s they added several pages to the probes section of their catalogs that explained the differences between the probes in a way that was helpful. What you should look for
is in the Probes section of the later Tek catalogs. Not every Tek catalog has this information but by about 1989 and onward there was a page devoted to showing each probe size (miniature, subminiature, 3.5mm, 2.5mm, etc) and EVERY part and accessory for that probe and how they were all attached. It includes part numbers for each item in the drawings.

I think the 3.5mm and 2.5mm probes were an attempt to make it clear from their description how big the probe diameter is rather than using less descriptive terms like "miniature" and "sub-miniature".

I often have to refer to these pages myself when I am trying to figure out which accessory goes with which probe.

Dennis Tillman W7PF

-----Original Message-----
From: Greg Muir
Sent: Saturday, August 24, 2019 5:26 PM

I guess this is sort of an academic question about how Tek refers to their P6xxx probe series via a dimension.

In several probe accessory references Tek Refers to some probes in the series as "2.5mm" and others as "3.5mm" probes. I am trying to figure out to what part of the probe these dimensions apply. i can't seem to find any dimension on the probe body that comes close to those referenced except possibly the length of the bare tip. Could this be it?

Any ideas?

Greg





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Dennis Tillman W7PF
TekScopes Moderator

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