[R-390] R-390A Coax question

[DW Holtman]

Hello to the group,

I have a couple of questions that I hope someone can help me with.

Is the coax cable used throughout the receiver 50 ohm impedance?

If it is 50 ohm, would RG-74 make a good replacment, or should I try to find some better coax, with lower loss? The runs are only about 1 foot long, I think the loss at HF would be insignificant, but maybe someone has some better ideas.

How hard is it to re-work the Mini BNC connectors? I have looked high and low on the web and don't think they are available.

Thank you in advance for all of your help.

73's
DW Holtman
WB7SSN