I have several lengths of RG8 (and other types) coax that are more than 25
years old and i am trying to sort good stuff from stuff to throw away. Most of
them are over 100 feet. I have used my MFJ-259B using the distance-to-fault
feature to try to determine the length. I tested one coax that was 30.5 feet
exactly to see if I can get reliable figures for the length. The MFJ-259
indicates it is only 29.4 feet after multiplying the displayed length times the
appropriate velocity factor. In this case, it was RG-142 with teflon
dielectric. The only potential I see for any error is how the coax is
terminated. The manual says to just leave the coax unterminated on the other
end when the measurement is made. But it also says, that more accurate
measurements might be obtained if it is terminated in a resistive bad match as
opposed to a reactive bad match.
Does anyone have experience with this and found a reliable method?
On the good side I have checked some of the coax lengths and found that the
loss measurement feature of the MFJ-259B tracks within 0.1 dB of the
measurement made with a professional quality tracking generator and spectrum
analyzer.
GregN9GB
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|