Re: [amsat-bb] Coaxial's "Z" request

["i8cvs" <domenico.i8cvs@xxxxxx>]

Hi Mak, SV1BSX

I am sure that  looking at the type of dielectric of your coax cable you can
fix  the velocity factor of it with a small error.

Cut  any odd numbar of 1/4 electrical wavelenght of your cable preferably
for a low frequency in HF and 28 MHz is OK

Connect one end of  the above line to the output of your VSWR meter and
load the other end of the line with three 100 ohm 1 watt carbon resistors in
series connected with very short leads to get 300 ohm ( 288 ohm is the right
value of  load to get a perfect match )

If the characteristic impedance of your matching line is 120 ohm than the
measured VSWR will be very close to 1

This is what I would do having no special instruments in my hands but since
the impedance written in your cable is 120 ohm than any VSWR a little bit
greater of 1 will be due only to a imperfect measurement.

Best 73" de

i8CVS Domenico

----- Original Message -----
From: "SV1BSX" <sv1bsx@yahoo.gr>
To: "Amsat-BULL" <amsat-bb@amsat.org>
Sent: Thursday, April 06, 2006 11:57 PM
Subject: [amsat-bb] Coaxial's "Z" request


> Hi all,
>
>  I bought a Coaxial-cable that mentioned  Z=120 Ohms.
> (I thought that they will be very useful for "stubs").
>
> The type of coaxial (written on plastic cover) is:
>
> 2002  HCE  02 0798
>
> Unfortunately, looking for specifications ( VF etc) is impossible to
> find anything about it. Seems to be completely unknown coaxial
> cable. So now I'm wondering also about the impedance of it !
>
> Is it possible to measure the "Z" into an unknown coaxial with simple
> instruments which are available in our Shacks in order to confirm if the
> impedance is 120 Ohms?
> Any suggestion or idea is welcome.
>
> Thanks in advance.
>
> 73, Mak SV1BSX
>
>
> sv1bsx@yahoo.gr
> http://www.qsl.net/sv1bsx
>
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