Re: Type 519 -- Why 125 ohms?

Jim Ford

I thought it was about 77 ohms.  75 ohm TV coax being very close.  Maximum power handling supposedly occurs for about 30 ohms, and 50 ohms is a compromise between lowest loss and highest power handling.  I've always thought that there would be variations In both  with dielectric and conductor materials and geometry (e.g. coax, microstrip, coplanar waveguide, etc).  Don't have the analysis chops to calculate it myself....             Jim Ford Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: Göran Krusell <> Date: 5/13/21 12:55 PM (GMT-08:00) To: Subject: Re: [TekScopes] Type 519 -- Why 125 ohms? My memory tells me that the Germans in the 1930s (?) made calculations to figure out if there would be a certain characteristic impedance that would give you the lowest possible cable losses and found 60 ohm as the result. Or am I out in the blue?Göran

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