Print

[FLANNERYD]

Hi –
I’m not a ham radio enthusiast YET, but I know someone here can help me with a problem. I have a Shakespeare marine antenna on my RV, which I’ve connected to a Midland NOAA weather radio, via the radio’s EXT ANT RCA port. The external antenna is not working. When the antenna cable’s RCA connector is firmly plugged into the radio, the radio’s signal strength indicator goes to zero bars. However, if I touch the RCA connector around the outside of the radio’s EXT ANT port (not plugging it in), the radio’s signal strength indicator maxes out at 5 bars.

I confirmed the frequency I should be receiving, with a separate NOAA radio, so I know there is a NOAA signal and that it can be tuned in.

The antenna cable is RG58, and I used an extension RG58 to get the length I needed.
Does it sound like I have a short in one of the cables or maybe a bad connector? I cannot really test for continuity, as one end of the cable is on the roof and the other is inside the trailer…

Thank you for any advice!

[KU4UV]

Sounds like either a shorted connector or something is grounding out at the connector end.  Just my two cents though.  Good luck with it.

[N8TGQ]

 Sounds like a short somewhere. If you can disconnect the antenna from the coax, you could check for a short at the connector end by testing across the inner and outer parts of the connector. If you see a short, disconnect the extension and try the test again across both the extension and the original coax to the antenna.
 I think that antenna has a matching coil, so you should see a short across the connector's terminals with the antenna attatched to the coax.
 Good luck!

[W9IQ]

I cannot really test for continuity, as one end of the cable is on the roof and the other is inside the trailer…

There are a couple of tests you can do with the cable in place.

For both of these tests, ensure that neither connector is touching anything metal or conductive.

Disconnect both ends of the cable. Use an ohmmeter to confirm that the cable isn't shorted by touching one meter lead to the center pin and one to the shield (outer conductor). It should not show any resistance.

On one end of the open cable, short the center pin to the outer shield. You can do this with a clip lead, with a glob of crumpled aluminum foil forced onto the connector or with the help of a friend with a coin. Then use the ohmmeter on the other end to confirm that the cable now reads shorted i.e. 0 ohms.

- Glenn W9IQ

[K4PIH]

Sounds like either a shorted connector or something is grounding out at the connector end.  Just my two cents though.  Good luck with it.

A few things come to my mind. Since when you touch the RCA connector on the WX radio it comes alive, that means you are actually an antenna. When you connect the external antenna signla indication dropd to zero, that may be
there is either a short in the coax somewhere, or your run of RG58 is too long and the incoming signal is just being absorbed by the coax. How long is your coax run and how did you make the connection at the extension point?

[FLANNERYD]

A few things come to my mind. Since when you touch the RCA connector on the WX radio it comes alive, that means you are actually an antenna. When you connect the external antenna signla indication dropd to zero, that may be
there is either a short in the coax somewhere, or your run of RG58 is too long and the incoming signal is just being absorbed by the coax. How long is your coax run and how did you make the connection at the extension point?

My total coax run is about 35ft (coax from antenna + extension coax) and they're connected with PL-259 Male to SO-239 Female connectors. I did make the PL-259 connector, on the roof of the RV, on a very hot day because... well, poor planning. And it was the 2nd connector I ever made, so... maybe I messed that up. I will check that connector with my meter. Thank you for your help!

[FLANNERYD]

Thanks to everyone who provided suggestions. I'll try these out and hopefully get to the source of the problem!

[W1RKW]

corrosion?

[WA3SKN]

Most likely, the marine antenna is a collinear design and would have a DC short in it.  However, checking for opens and shorts with an ohm meter would be a start.

-Mike.

[W1VT]

There is also the possibility that the matching network for the marine antenna doesn't work for NOAA.

[FLANNERYD]

Thanks again for all of the suggestions. Short story is that YES, I did have a short. With the suggestions here, I used my multimeter to check the cable, and that was the issue. Long story is that the installer had accidentally cut the cable and had "repaired" it. I never knew which cable he was talking about, as he ran several from the roof of my trailer, for many things (NOAA, cell, solar). I found the "repair" and that was the short. It's now fixed the right way.