EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: icon on February 25, 2014, 10:45:26 am
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Hi
A Tek 2245A followed me home the other day. It came with two P6109 (fixed x10 attenuation) probes that have a 'readout pin' built into the BNC connector. Between the pin and ground is an 11kOhm resistor - the pin mates with a ring around the BNC connector on the scope and tells it to switch to 'x10' mode.
It also came with two other 6109 probes *without* the pin. Has anyone come up with a neat way of fooling the scope into recognising a x10 probe? I have seen online a suggestion that simply shorting the ring to ground works, but that seems a bit brutal.
Thanks
John
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An 11k resistor is out of the question?
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Well yes, thanks - that had occurred to me. It was the 'neat' bit I was looking for - some genius re-use of a common household object to neatly hold a resistor in contact with the ring and the BNC ground sleeve with getting in the way and whilst being easy to remove if needed. Someone's bound to have come up with something - this is the Internet, after all.
It would have been nice if Tek had included a 'x10 override' switch, but sadly this isn't the case.
Regards
John
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You can take a BNC female to male, on the scope side of the Adapter you can bend a small piece of spring steel, solder it to the BNC connector. On the other side of spring steel clamp you could solder a SMD 11K Ohm. It is a little tricky to get it nicely build, but it is a simple way to get a x10 Adapter.
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Drill a small 0.8mm hole in the outer body of the unpinned probes and place a short copper wire in it and place the resistor ( smd) between that and the ground connection inside the probe body. that will look almost original.
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I've taken a rubber washer with a hole diameter the size of a BNC jack, and wrapped thin bare wire around it, toroid style. When it is sandwiched between the probe BNC plug and the sense ring on the scope, it shorts the ring to fool the readout. You could probably fit a 1/8 watt resistor in there using the leads, or thin washers, as contacts, if it has to be a specific resistance. Kind of quick and dirty, but mine has worked for years. ;)
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Shorting the sense ring to ground is fine... the scope is designed to work that way.
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I think the toroidally-wound rubber washer is the winner, thanks. I've just checked and shorting it switches to x10, drawing ~1mA in the process.
Hey, can't you get conductive rubber? Hmmm...
John