Re: TM 504 Power Module Questions

Tom Lee

The standard cable was good old generic RG-174, which is 50 ohms.

-- Cheers,

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

On 7/14/2021 19:01, Dave Daniel wrote:
Ah, yes! I had forgotten the name. Thanks.

I still don’t know the characteristics of that coax. Perhaps I will get a chance to measure them someday.


On Jul 14, 2021, at 21:36, Tom Lee <> wrote:


Ron Peltola devised this clever interconnect solution.


Sent from my iThing, so please forgive brevity and typos

On Jul 14, 2021, at 17:53, Dave Daniel <> wrote:

Some of the 73xx (maybe other 7xxx ‘scopes as well) used “strange” small-diameter coax for interconnects, with small concentric gd-plated connectors. I have no idea what the characteristic impedance of these interconnects are. There is a photo on TekWik which shows these - white with spiral colored stripes.

I wonder if these are what was used for the aforementioned interconnects.


On Jul 14, 2021, at 20:38, Jeff Dutky <> wrote:

For the internal coax connections you can use one of the smaller diameter coax cable types: RG174/U, RG178/U, or RG316/U (and possibly others). I've bought all of the above from various sources, including Mouser, JameCo, and Amazon. For the short hop from the backplane to the rear connectors I doubt that it makes much difference which kind you use (but I'm not an expert on this, so I stand ready to receive correction).

-- Jeff Dutky

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