7T11 diode tunnel destroyed connecting a 15pF 1:10 probe?

Miguel Work

Can a 15pf probe destroy the CR152? 1:10 ground clip is connected to chassis. Diode is connected to -15V.



Miguel Work

gnd scope is connected to ground, which is the maximun energy that the diode can withstand?

Tom Lee

Hi Miguel,

Although anything is possible, killing a tunnel diode with ESD from a scope probe is pretty improbable. Over most of its I-V characteristic, a tunnel diode looks like a very low resistance, which is extremely effective at snubbing.

Also, I haven't followed this thread too closely, so I don't know what testing led you to conclude that the TD is dead. If you used a multimeter, a good TD will be hard to differentiate from a shorted TD. You can reliably identify an open TD with a multimeter, but you need to use other means to test a TD reliably in the general case.

-- Cheers,

Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070

On 9/13/2021 01:35, Miguel Work wrote:
gnd scope is connected to ground, which is the maximun energy that the diode can withstand?

Miguel Work

Hi Tom

Yes, the output tunnel diode was "working", but it haves >100 ohms resistance

Arm diode is ok, but is diferent kind, is a 10pf, de output is a <5pff

When I first tested operation I don´t have output in trigger otuput, so I went directly to test TD operation with probe.

Output TD was bad, open, so I replaced it with the same diode. It worked but only for a few minutes, bias pot was at max, but I don´t belive that this was the cause of the problem,

Some times it has a 100 ohms resistor, others is open, the second diode that I replaced

Then I have replaced it for a russian AI201A 3.5pF 10mA GaAs and now is working

So, I suspect that the capacitance probe has some efect destroying the TD diode. Tunnel diode is connected to -15V, so when I connect the probe it charges 15pF, capacitance probe, through the tunnel diode.