Re: Replacement probes


Miroslav Pokorni
 

Hello Stan,

Those that you say were crimped are probably for P610X probes. I never tried
to repair those cables, I only replaced them. The P610X were modular and you
could buy box, cable and tip. I do not think those probes were pinnacle of
Tektronix' quality, connectors that mated to cable were pretty poor. It
happened more then few times that probe would quit working again shortly
after cable replacement 'repair'. Mating and unmating cable and end piece of
probe would fix the problem but that was a short term solution, the end
piece needed to be replaced. I found it overly expensive to repair those
probes and at one point I started to buy new probes when an old developed
trouble and just saved old ones to use as spare parts.

The cables that I tried to repair were for P600X. Cable ends were spot
welded and soldering worked with lot of scraping and use of Aspirin as flux.
That soldering taught me to treat probes with respect.

I am not really surprised that Tektronix did their own cable, a probe cable
does not have other applications. The Beldens of this world would not design
and make 10000 yards of probe cable just for Tektronix and hp. Maybe now a
common cable manufacturer might use one of their machines to make one run of
customer designed cable and price it accordingly, there seems to be more
custom runs now than there was in 60s.

Regards

Miroslav Pokorni

----- Original Message -----
From: "Stan & Patricia Griffiths" <w7ni@easystreet.com>
To: "Miroslav Pokorni" <mpokorni2000@yahoo.com>
Cc: "TekScopes" <TekScopes@yahoogroups.com>
Sent: Saturday, June 21, 2003 6:26 PM
Subject: Re: [TekScopes] Replacement probes


Back in the "old days" (before about 1980, or so), Tek used to manufacture
their own probe cables. They did this because, like all components that
Tek
manufactured, they could not find suitable cable on the market from other
manufacturers. If you have ever had occasion to try to repair a Tek
probe,
you probably have noticed that the coax used for the probe cable has a
VERY
fine center conductor and you can't really solder to it either. It is
wire
with distributed resistance and the connections at both ends are crimped.
Repairing a damaged probe cable generally means replacing the probe cable
with a new one. I have no idea what Tek does these days for good probe
cable. My guess is that, by now, other suppliers of cable have figured
out
how to make quality cable.

Tek even made the machines that made the cable. Watching a machine weave
a
braided shield over an insulated center conductor is a process that defies
description . . . so I won't even try it . . . I probably have some
pictures of these huge machines somewhere in my 10,000+ pictures that I
salvaged when Tek threw out their photography archives. In all fairness
to
Tek, they saved a thousand or so pictures and I got the left-overs.

Stan
w7ni@easystreet.com

----- Original Message -----
From: "Miroslav Pokorni" <mpokorni2000@yahoo.com>
To: "Stan & Patricia Griffiths" <w7ni@easystreet.com>
Cc: <TekScopes@yahoogroups.com>
Sent: Tuesday, June 17, 2003 5:59 PM
Subject: Re: [TekScopes] Replacement probes


Hello Stan,

I think in your career you saw more then few probes that were dirty and
customer was asking you how comes that the other guy could make them for
less.

What I noticed about 'third party probes' is that the only specification
given is the bandwidth. I have never seen that any of them go into rise
time, let alone signal aberrations. The rise time spec for this 'Texas
probe
' is just an extension of declared bandwidth, a calculated value. That
seller got quite a bit money for something that is quite questionable.

As for switch, I also wonder about its effects on performance, even at
100
MHz. Tektronix had one of those, too.

I understand that one of tuff things for probe is the cable. When you
deal
with high impedance at cable ends, the effects of dielectric absorption
(charge in dielectric remaining after bringing voltage to zero) become
noticeable and that leads to unwanted ringing.

Regards

Miroslav Pokorni

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