Coaxial cable Issue

[Rahel]

Hi Guys

I've SLR8000 VHF repeater and both TX/RX antennas are using separate antenna on 70m tower.

I've tested both antennas VSWR and it's 1.0-1.2 but the strange thing is after antennas installed on the tower I'm trying to test the VSWR using antenna tester but it gives me infinity value of both TX/RX antennas.

Any idea about this case and is that possible that damages happened to the cable or the power of antenna tester not reach up to 70m... In addition, how to check the cable?

 

[merlin]

Given infinity on both antennas, you have an open connection from the antenna tester to the feed connection, or your tester has failed.
Even my Nano VNA is good on 200 foot of LMR600.
For this run, I presume you are using 7/8 heliax (at least 1/2 inch) and properly anchored to the tower.
The best test for cable is time domain reflection, bad kinks or connectors will show as ripples.
A short down the line will display total reflection (x time) and can corelate to the distance to the short.
Open on the far end will show as a total reflection at the end, then terminated should be a strait end.
The antenna should show the same as a terminator. Like being able to 'see' S21 (SWR)

 

[TampaTyron]

Sounds like bad cale or connectors. Can you tell us specifically what cable and connectors are in the system what tester, who put it all together, etc? TT

 

[techman210]

Define “antenna tester”

Is it a directional wattmeter or a low cost VNA from China? What cable?
A Good VNA is the best tool to test the return loss of the “system” (cables, lightning suppression, connectors and antenna)

A good test of a “antenna tester” would be to put a proper 50 ohm termination on it, and reflected power should be near zero.