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I have much enjoyed the recent discussion here about the 7T11/7S11/7S12
sampling plugins and have learned a lot from the contributions.

I have a long-term quest to get my Soviet Ya4S-100/Ya4S-101 sampling
plugins working properly. They're roughly equivalent to the 7T11 and 7S11
but with some neat features, most notably a delta delayed timebase and
slideback-type voltage measurement, both with digital display on the
scope's readout. The problem is that I don't have the sampling head for
them. I'm searching high and low for one (and learning quite a lot of
Russian in the process) but they're like hen's teeth and always seem to
have gone missing. The official sampling head is a dual channel feed
through sampler with SR50-262 (almost identical to 'N' type) connectors for
input and output. The good news is that the schematic is available, though
seems to have been drawn by someone whose aim was to minimise the use of
paper and ink rather than to create useful documentation.

The sampling plugin has a 19-way connector for the sampling head. This
carries +/-15V, the signal and feedback for each channel, a single strobe,
and a mysterious signal called 'threshold' which looks like a TTL logic
output which alternates state on each trigger.

The good news is that my sampling plugins seem to be working well and all
the signals on the connector do the right things, so the project is worth
pursuing. My idea is to create an adapter cable so I can use Tek S-series
sampling heads until I find the original one. I don't have any S-series
heads at the moment, only SD-22 and SD-24 ones which involve too much
software, so I'd have to buy one to try out.

I've looked at the manuals for the 7S11 and various sampling heads. Is
there a clear specification anywhere of the interface, for example the
amplitude of the strobe pulse and the signal and feedback connections? I
would be quietly amused if the Soviet system turned out to be electrically
compatible with the Tek one...

All advice and thoughts much appreciated,
Chris

It is going on the back burner. I am going to put it together for its own safety. I am out of ideas and last I looked so was everyone, so I might just use it as a 12 volts scope or something...

If anyone gets any ideas I am all ears. For now I got bigger fish to fry, which ummm, by the way...

Yup, those 7000 series are next. Coming soon.

Thanks! That's jumper P1445, I believe.

What's the "PDA lead "? I don't recognize what PDA stands for...

My 465 SN is B175976.

I am looking at a manual marked "tek-070-1330-00" (236 pages, with yellow addendum pages added in the back), as well as a manual for later version 465's (070-1861-00, B250000 & up, says Rev B, June 1975, 291 pages).

I think the first is the correct one, but it is more limiting (for instance, no trouble shooting flowchart).

So... if I remove that ground strap, and I still don't see anything on the
screen (not even using the beamfinder)... that suggests the HV multiplier
is NOT the fault that's causing my problem?

Is this the ground strap you mean? /g/TekScopes/
photo/49286/0?p=Name,,,20,1,0,0

Doesn't seem likely to me, as it isn't under the HV cover, but near the
front end... but it is the only ground strap visible on that side of the
main board on my scope.

Here is a photo of the area under the HV cover, and I don't seen anything
resembling a ground strap coming up between the "main board and the
vertical amplifier board" as you describe:

/g/TekScopes/photo/49286/1?p=Name,,,20,1,0,0

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Craig Sawyers
Sent: 28 May 2018 07:02
To: [email protected]
Subject: Re: [TekScopes] Tek S4 sampling head

Frye reckons that the diodes (which will be schottky barrier) switch in 2ps. Which implies a 3dB
bandwidth per diode of 175GHz.

The nearest you can get to that performance are microwave schottkys, for example this range of

devices from MACOM which have a
bandwidth of 80GHz. They have a junction capacitance of 0.02pF, which implies that the S4/S6

have a junction capacitance of 0.01pF (ie 10 femto-farads). And scaling from MACOM's drawings, the
actual junction is about 50um square. The S4/S6 diodes are 30um square - so 0.36 times the area

capacitance) of an 80GHz device. Scaling that gives a bandwidth of the S4/S6 diodes of 222GHz -

enough to the 175GHz worked out from Frye's data.

Which is why the darned things are static damageable. Take a human with a body capacitance of

and an unspecified but almost always significant voltage up to 10kV, and connect that to a

with 10fF capacitance. The result ought to surprise no one.

Note from the MACOM datasheet two things. First is a junction breakdown voltage in the range 4.5 -
7V, entirely consistent with the S4/S6 spec that says do not exceed 5V on the input. And secondly,
handling where MACOM say "Static sensitivity: Schottky barrier diodes are ESD sensitive and can be
damaged by static electricity. Proper ESD techniques should be used when handling these Class 0
devices"

Some interesting numbers here though regarding body voltage when properly grounded

static-se
nsitive-operations.php . In particular "international ESD losses that now exceed an estimated $90
billion"

All of which is why I take very great care of my unfixable samplers and fast pulse generators. And

urge others to do so too.

Craig

Per square nanometer. 1 square nanometer is 30um square - which is the
size of the S4/S6 diode junctions.

This is the designer George Frye's explanation of operation, including
a picture of the hybrid

I think it can easily be seen that this is not a repairable assembly.

Craig

Per square nanometer. 1 square nanometer is 30um square - which is the size of the S4/S6 diode
junctions.

This is the designer George Frye's explanation of operation, including a picture of the hybrid


I think it can easily be seen that this is not a repairable assembly.

Craig