Ron Wright,
C'mon Ron, I asked to get a feel for the references used in your explanation
of how coax has a lower freq limit, not a compilation of your library
collection.
It appears that when you get a specific question you cannot provide an answer
to, you go into a rambling dialog
From: Gary Schafer [EMAIL PROTECTED]
Date: 2007/09/02 Sun PM 09:07:18 CDT
To: Repeater-Builder@yahoogroups.com
Subject: RE: RE: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re:
Duplexers
Isnât it interesting to note thatthe impedance goes UP at low frequencies
This could be correct in that say a 50 Ohm coax at 10 MHz would be say 120 Ohms
at 100 kHz or 90 Ohms at 50 kHz...freq dependent. There is still L and C.
However, this would have to be for a specific design or application.
It would affect wideband stuff like video and it does. I guess one
One can see there becomes a point where the coax will not
look like coax at low frequencies or atleast have a
characteristic impedance of something other than it normal value.
Most of this is true (although I don't know what you mean by coax will not
look like coax), and I already
Hahaha a audiophiles... can sell them anything no need for real
physics, just tell them that this device will make things sound better, back
it up with a BS statment that doesn't apply, and charge them 100 bux.
On 9/3/07, Jeff DePolo [EMAIL PROTECTED] wrote:
One can see there
Allan,
Well I think most on here do not quote their sources for many got info long
time ago and from many sources.
If you want a list of some of what I got...well ok:
Reference Data for Radio Engineers, ITT (have had about 30 years so probably
should update, but still the RF stuff is pretty
Jesse,
You got it, well said.
If you take a simple 100 ft piece of 1/4 superflex a typical value for its
C=2400pf, L=6 uH and R=570 Ohm.
At 5 Hz the Ls and Cs mean little compared to the R.
At 10 MHz Ls and Cs mean a lot compared to the R.
One can see there becomes a point where the coax will
Jeff,
I have plenty of text books here, oh well. All refer to impedance as Z and
Z=R+jX or Z = magnitude and phase angle. A 500 Ohm resistor has an impedance
of 500 Ohms or 500+j0 or 500 0 deg phase.
I think in Jesse's and my last posting you might see about the low and high
freq
So to plug some numbers in:
Say you have a cable with the following specs (50 ohm cable)
Capacitance of 100.3 pF/m
Inducatance of 251 nH/m
Resistane of 0.164 ohms/m
Shunt conductance of 12.8 mS/m
Zo = sqrt [ (R + j 2 pi f L ) / (G + j 2 pi f C ) ]
at 100 Hz= 113 ohms
at 1 Khz= 111 ohms
at
.
73
Gary K4FMX
_
From: Repeater-Builder@yahoogroups.com
[mailto:[EMAIL PROTECTED] On Behalf Of Jesse Lloyd
Sent: Sunday, September 02, 2007 4:10 PM
To: Repeater-Builder@yahoogroups.com
Subject: Re: RE: RE: RE: RE: RE: RE: RE: Re: Re: RE: [Repeater-Builder] Re:
Duplexers
So
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