MFJ849 meter

[clucas6308]

Hello all,

I have been struggling with high SWR readings. While ohming out cables I found continuity between the center and the outer threads on the bare meter. no continuity on the VHF side. Also I had continuity on the center and outer shield to the antenna, Maco 5/8v. Do I need to set the meter to higher resistance?

Thank you.

 

[clucas6308]

Update, the Maco 5/8V has continuity between the center and outer threads of the SO connector. Should it be like this?

 

[WA0CBW]

Set the meter for continuity (lowest range). The 5/8v may have a matching network (loading coil at the bottom) which would show continuity from center conductor to shield.

 

[majoco]

A loading coil is in series with the antenna - it should show open circuit. A 5/8 wave antenna has a matching coil ( and maybe a small capacitor) with a tap for the feeder, the bottom end to ground and the top to the whip. Go to your antenna and disconnect it - disconnect the VSWR meter too. From the bottom measure the resistance from shield to the centre conductor - it should be open circuit, high resistance or whatever your meter shows for open circuit. Now go back up to the antenna and short the shield to the centre with a clip lead or something. Now go back down to the bottom and check for zero or very low resistance, hopefully less than 10 ohms - NOT the characteristic impedance of the cable. If you're going to transmit then you should have a 50 ohm load suitable for VHF or higher depending on your use - connect that to the top, measure it's resistance from the bottom - should be 50 ohms plus the cable resistance. Reconnect the VSWR meter and transmit into the dummy load to check the VSWR - it should read very low, less than say 1.2:1. Don't exceed the power rating of the dummy load. Reconnect your antenna and read the VSWR - if it's not very low then we now know that it's the antenna that's suspect - not the cable or the VSWR meter.