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Help with vintage Tek scope

Hi, I'm wondering if someone out there knows the type of coax used in the

500-series extender #013-055... I'm guessing by looking at the driver circuitry it would ideally drive 93 ohm coax, but the (totally unmarked) coax used in the extender has the following dimensions: conductor: 15 mils , stranded dielectric: 95 mils dia, white, seems to resist heat quite well, but not as well as teflon total outer dia: 140 mils

The only 93 ohm coax I've dug up is RG-62/AU, which has a thick solid conductor and is way stiffer and larger than the coax used in the extender. I can't seem to match this coax to anything I know by the dimensions alone, and I don't know the impedance I need for sure. I'm guessing also the coax has a very low pF/ft rating to help those tube drivers out a bit. Thanks!

Reply to
Stuff
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I don't have the specs here, but that sounds like RG-174, which is just 50 Ohm.

The RG-62 is low C and 93 Ohm, and might even be better for your extender. Is there room for it?

The plugin probably doesn't have its full bandwidth with the extender installed, and an extender with the 6 digit part number would have been an early one, which might have been made with one of the earlier

500 series (lower bandwidth) scopes in mind. I don't know, but it's possible that tek changed the cable in later versions. -

----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

-----------------------------------------------

Reply to
Jim Adney

Hi, The RG-174 I have here is the wrong dimensions, for one thing, the ratio of inner/outer diameter is different, and is smaller. It's dirt cheap, it melts very easily. ie, I think it's crap...

Oh sure, but the stiff nature of the 62 makes me worry that at some point, the cable will destroy the metal tabs on the blue ribbon connectors I have. The 62 has a steel copper covered conductor which is strong enough to break the tab in two.

I never thought of that. The extender came with the 547, which both came from a tech of Radio-Canada, I always assumed they went together. Certainly I never noticed any large differences when using it.

I am trying to make a long extender so I can work on plug-ins more freely. The plug-in I want to fix is a TDR plug-in, which I would use to find the impedance of the cable... Oh well.

I'm still waiting for my Teflon #22 wire to come in to build the extender, so I have time to find the type of coax.

Reply to
Stuff

Tek made a lot of custom coax in those old days to get the exact delay characteristics they wanted. It was one of their "trade secrets" that made them lots of money. It is also why their probes were always better.

So, don't be surprised if you can't find a match.

Steve.

--
Steven D. Swift, novatech@eskimo.com, http://www.novatech-instr.com
NOVATECH INSTRUMENTS, INC.      P.O. Box 55997
206.301.8986, fax 206.363.4367  Seattle, Washington 98155 USA
Reply to
Steven Swift

snipped-for-privacy@eskimo.com (Steven Swift) wrote in news:d2aepm$v68$ snipped-for-privacy@eskinews.eskimo.com:

AFAIK,TEK never made their own coax. Perhaps they special-ordered some from cable manufacturers.

--
Jim Yanik
jyanik
at
kua.net
Reply to
Jim Yanik

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