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

[Charles Steinmetz]

Jacques wrote:

> I wanted to use a replacement coax that is the closest to the original one,
> especially regarding the capacitance.
> *   *   *
> a replacement one having the same impedance should have a quite close
> value of capacitance per length

All standard 0.1" (nominal) coax has capacitance values between 23 and 
29 pF per foot (75-95 pF per meter).  75 ohm coax will have somewhat 
lower capacitance than 50 ohm coax, for similar materials and 
constructions, but there will be no discernable difference between them 
at the lengths used in the 390A.

Again, any coax that will fit the connectors will work fine -- you will 
not be able to detect any difference between them, aside from shielding 
effectiveness.

One more thing not to worry about when working on R390s/R390As.

Best regards,

Charles