Thread: F-connectors
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Old May 16th 04, 09:29 PM
Reg Edwards
 
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To save the trouble of calculating it I'll take a guess. A connector less
than 1" long of impedance 51.5 ohms in a 50 ohm system will NOT produce an
SWR of 1.03:1 or anything anywhere near to it at frequencies less than 1000
MHz.

A 1" long connector WILL produce an SWR of 1.03:1 around 3 GHz but no worse.
If you can reliably measure it.

What matters is the ratio of connector length to wavelength along the line.

For the same reason, at HF, bringing the two wires of an open wire line
close together for the purpose of drawing them through a single small hole
in the wall, will not produce any noticeable effect on line performance.
----
Reg.

=================================

"Richard Fry" wrote in message
...
"Reg Edwards" wrote
Provided the mechanical connection is sound, you can use any coaxial
connectors you like, regardless of nominal impedance, at frequencies

less
than about 300 MHz without any observed ill effects.

_________________

??? Using connectors that don't maintain the characteristic impedance of

the
transmission lines they connect _will_ produce undesired effects. The
effects may be negligible to amateur radio operators used to operating
transmitters into rather high mismatches, but they would never be

tolerated
in most professional operations, including high-power broadcast systems.

Years ago a common impedance for rigid transmission line used in broadcast
systems was 51.5 ohms. Later the more common value was/is 50 ohms. While

a
mechanical adapter was available to allow connecting a 51.5 ohm inner
conductor to 50 ohm inner conductor (SWR= 1.03), better installations
installed an RF transformer section at these interfaces.

A 1.1 SWR at the input of a TV transmit antenna using ~500 or more feet of
transmission line will produce a visible "ghost" in the transmitted

picture,
as seen by a careful observer. At 1.25 SWR it can be seen, and will
objectionable to almost everyone.

RF

Visit http://rfry.org for FM broadcast RF system papers.