Buck wrote:

...
Is this 5 times the diameter in turns?

Buck:

No, I meant using a "single layer solenoid formula"/table/graph, pick an
inductive reactance which would offer an impedance (choking effect) of
10X the impedance of the coax in question--or in effect, 50 X 10 = 500
(depending on your physical limitations for the choke, this may not
achievable ... a lower value may have to be accepted.)

Also, you may wish to check the self-capacitance against the inductance
of the coil and note the resonate freq of the choke, making sure it is
working to your advantage rather than you disadvantage.

Regards,
JS