[R-390] R-390A RF DECK COAX CABLES IMPEDANCE

[Charles Steinmetz]

Jacques wrote:

> Does anybody already worked out the impedance of the coaxial cables
> connecting to the RF DECK in a R-390A ?
> They look very much like 75 ohms Teflon to me... RG-179/U ?

Or 50 ohm RG-316.

Why do you want to know?  All of the coax runs in the 390A are too short 
to support wave propagation modes at the frequencies they are handling, 
so they are really operating as simple unbalanced shielded cables, not 
as transmission lines.  Note that the source and load impedances of the 
connected circuits are not matched to the coax's characterstic impedance.

Any cable that fits the connectors will work fine.  If you are looking 
to optimize, choose the cable with the most effective shield.

Best regards,

Charles