How much can the impedance of coax vary from its characteristic impedance?
Richard,
You asked if the load is shielded. I was using a MFJ dummy load and
the resistor is inside a metal enclosure. Not sure if this mets your
shielding criteria.
I did have twelve #31 ferrite beads (1.125"X.0.5") on both the input
and output end of the cable, so I can say for sure that aspect was
taken care of. I didn't notice any changing values whenever I would
move the coax around or grab onto either.
-Scott, WU2X
On Aug 19, 1:20 pm, Richard Clark wrote:
On Sun, 19 Aug 2007 16:28:32 -0000, wrote:
However my actual measurement with both the MFJ259B and LP100 showed
an impedance of 74 + j0 Ohms.
Hi Scott,
Unless both ends are completely shielded (which is to ask: Is the load
a shielded load?), then you need to choke things.
A quick test would be to take the load end of the line and coil it 8 -
12 turns around a 6 inch cylinder. Does this change your impedance
reading? You will need this choke for your antenna anyway, so plan on
something like it.
73's
Richard Clark, KB7QHC
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