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Old October 2nd 05, 07:57 AM
David
 
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Default Tables of Er for various metal tubes ?

Does anyone know where I can find Er tables for various type and diameter
of metal tubing so I can calculate Velocity coefficient Vp ?

Thanks in advance

Regards

David
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Old October 2nd 05, 11:54 AM
Reg Edwards
 
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"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.


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Old October 2nd 05, 02:13 PM
David
 
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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.


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Old October 2nd 05, 05:42 PM
Dave
 
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what sleeve and what coax? you asked about Er for tubing and didn't mention
any other components.

"David" wrote in message
...
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.


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Old October 3rd 05, 07:06 PM
Reg Edwards
 
Posts: n/a
Default


"David" wrote in message
...
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 jacket of coaxial cable is usually a soft grade of
poly-vynil-chloride, PVC, which can have a dielectric constant
anywhere between 4 and 6.

The velocity factor along the outside of the coaxial braid depends on
the thickness of the jacket. To make much difference to the VF it has
to be an inch thick or more whereas it is probably only about 0.6mm.

I will have a guess and say the VF is about 0.95. You can forget
about it.
----
Reg.


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