On 3/4/2015 6:11 AM, Brian Morrison wrote:
On Wed, 04 Mar 2015 05:50:02 -0500
Jerry Stuckle wrote:

On 3/4/2015 2:29 AM, Jeff wrote:

Coax can NEVER be spliced without causing a huge impedance
mismatch at the point of the splice. This is not 60hz or DC. But
any ham with even a minor bit of technical knowledge should
understand this.


We are talking about 200kHz here not 200MHz!! Use could join the
coax with a bit of choc-block at that frequency and not see any
significant performance degradation.

Jeff


It doesn't matter if it's 200kHz. The problem remains.

It depends what you mean by 'problem'.


And yes, there WOULD be s"significant performance degradation" if he
used a bit of choc-block.

That is only true if the discontinuity is a significant fraction of a
wavelength, 200kHz is about a 1.5km wavelength, in coax that would be
about 1km with typical velocity factors. A choc block is about 10mm
long, so it is 1/100,000th of a wavelength. I would not expect any major
problem but it could be used to experiment and cleaned up later if
necessary.


Incorrect. It all depends on the amount of the impedance bump. The
larger the bump (and there always will be one, even if connectors are
used), the greater the effect on the signal. And while the change in
impedance has a greater effect as you get a higher proportion of a
wavelength, a bump that's even small percentages of a wavelength can
create a significant loss.

In extreme cases, a short or open (which is much less than 1/100,000 of
a wavelength) would allow no signal through.


But if you understood ANYTHING about transmission lines, you wouldn't
make such a stupid statement.


Actually it's because Jeff understands about transmission lines that he
makes the statement, it isn't a stupid statement at all in the context
of the OP's question and the technical details of the installation.


It is a stupid statement, showing how little he understand transmission
lines.

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