OK, so the electrical wavelength of the tube will only be effected by
the dielectric material and it does not make any difference how large
the gap is between the Sleeve and the Coax ?

The frequency of operation is 920 MHz.

Do you happen to know what the covering is made of on the outer sheath
of RG174 ? The cable I have has a stranded inner core and seems to have
a PFTE dielectric. (Doesn't melt at all when soldering so I assume this
is what it is).



Reg Edwards wrote:
"David" wrote

Does anyone know where I can find Er tables for various type and

diameter

of metal tubing so I can calculate Velocity coefficient Vp ?


=====================================
The velocity factor of any conductor, including tubes, depends only on
what surrounds it.

If the surroundings are air, which is mainly oxygen and nitrogen, then
the VF = 1.00, equivalent, in metric units, to a velocity of 300
metres per micro-second. Or in ancient, old-fashioned units, it is the
far-less-convenient 669600000 miles per hour, give or take a few
100,000 miles. Who cares?
---
Reg.