Antenna Problems

[WSCU736]

I have a Comet-EFC. I have no receive signal at all. I tried 2 different radios with the same result. I used a multimeter set on ohms. From radio coax I tested center pin and the ground with coax connected to the antenna. And I get a OL on the meter. I have no clue what is wrong. I think the antenna is bad. Please help.

[SteveShannon]

4 minutes ago, WSCU736 said:

I have a Comet-EFC. I have no receive signal at all. I tried 2 different radios with the same result. I used a multimeter set on ohms. From radio coax I tested center pin and the ground with coax connected to the antenna. And I get a OL on the meter. I have no clue what is wrong. I think the antenna is bad. Please help.

I doubt that the antenna itself is bad. It’s much more likely that the coax or a connector is bad. Do you have a different piece of coax to try?
You know that the shield and center conductor are not shorted together when measured from the radio end. That’s good. 
Take the coax off the antenna and see if there’s continuity from one end of the center conductor to the other end of the coax. There should be. 
Do the same for the shield. It should show very little resistance from end to end. 
Let us know what you find. 

[Guest]

9 minutes ago, WSCU736 said:

I have a Comet-EFC. I have no receive signal at all. I tried 2 different radios with the same result. I used a multimeter set on ohms. From radio coax I tested center pin and the ground with coax connected to the antenna. And I get a OL on the meter. I have no clue what is wrong. I think the antenna is bad. Please help.

Might be.  Might be coax still.  With out an antenna analyzer it will be hard to tell. Can you test both sides of the center pin and make sure you have continuity that way first?  
 

you say you dint have rx.  Do you have tx? 

[WSCU736]

6 minutes ago, SteveShannon said:

I doubt that the antenna itself is bad. It’s much more likely that the coax or a connector is bad. Do you have a different piece of coax to try?
You know that the shield and center conductor are not shorted together when measured from the radio end. That’s good. 
Take the coax off the antenna and see if there’s continuity from one end of the center conductor to the other end of the coax. There should be. 
Do the same for the shield. It should show very little resistance from end to end. 
Let us know what you find. 

If I gett on the roof the wife would kill me. I am retired besause of 7 spine surgeries. I will try and get someone to take it down.

[SteveShannon]

11 minutes ago, WSCU736 said:

If I gett on the roof the wife would kill me. I am retired besause of 7 spine surgeries. I will try and get someone to take it down.

Yeah, don’t do that. 
Did this just suddenly happen or was it gradual?

Have you had much rain lately?  Moisture can ruin the ends of coax. 

[WSCU736]

11 minutes ago, SteveShannon said:

Yeah, don’t do that. 
Did this just suddenly happen or was it gradual?

Have you had much rain lately?  Moisture can ruin the ends of coax. 

Havent had rain in a couple weeks

[SteveShannon]

4 minutes ago, WSCU736 said:

Havent had rain in a couple weeks

Did this problem just suddenly happen or was it gradual?

[WSCU736]

6 minutes ago, SteveShannon said:

Did this problem just suddenly happen or was it gradual?

It just started. I thing I may have found the issue. One of my adaptors is showing continuty between the center pin to outside of the adaptor.

 

[SteveShannon]

2 minutes ago, WSCU736 said:

It just started. I thing I may have found the issue. One of my adaptors is showing continuty between the center pin to outside of the adaptor.

 

That’ll do it. 
So when you tested the cable and antenna before was the adapter out of the circuit?

[Guest]

1 hour ago, WSCU736 said:

I have a Comet-EFC. I have no receive signal at all. I tried 2 different radios with the same result. I used a multimeter set on ohms. From radio coax I tested center pin and the ground with coax connected to the antenna. And I get a OL on the meter. I have no clue what is wrong. I think the antenna is bad. Please help.

Skip all this, I see you found your problem before I could stop typing my long noisy post

 

The spec sheet on that antenna reads like nice equipment. I would try some process of elimination stuff before going to the trouble of pulling down that antenna. First, do the two radios "talk" to one another with the stock antenna(s)? Be sure you are testing with a simplex channel and not a repeater channel. Second, open the squelch on one of the radios and with the stock antenna, listen for traffic on the band. Check all of the non repeater channels. If you can hear someone then go back to the big antenna ans see if they are still there.

[WSCU736]

Thanks for all the help. I found a bad adaptor. Changed around my adpators and I now get full signal ob receive.

[WRUE951]

Did a bird hit your antenna. 

[WSCU736]

Just alittle update. Since I was testing this morning. My overall performancce of the radio is 100% better since the adaptor has been removed. Again thanks for all the help.

[WRYZ926]

A bad adaptor along with tree branches touching your antenna will definitely cause high SWR. I learned the hard way. I avoid adaptors as much as possible and make sure to keep trees well trimmed back away from my antennas.

[WSCU736]

Another update. I finally got my SWR meter. And checked my SWR and it was 1.2 on channel 16 and 1.7 on channel 30. And I have 85' of a coax run.

[SteveShannon]

9 minutes ago, WSCU736 said:

Another update. I finally got my SWR meter. And checked my SWR and it was 1.2 on channel 16 and 1.7 on channel 30. And I have 85' of a coax run.

What kind of coax?

[WSCU736]

Just now, SteveShannon said:

What kind of coax?

LMR 400

[SteveShannon]

Just now, WSCU736 said:

LMR 400

Good job!

[WSCU736]

Just now, SteveShannon said:

Good job!

Thanks

[WRYZ926]

37 minutes ago, WSCU736 said:

Another update. I finally got my SWR meter. And checked my SWR and it was 1.2 on channel 16 and 1.7 on channel 30. And I have 85' of a coax run.

Those numbers are perfectly fine. It is quite normal to see a slightly higher SWR on the repeater channels since they are 467 MHz versus 462 MHz. The SWR on channels 8-14 will probably be around 1.7 also since they are 467 MHz. And good for you on using LMR400 instead of some cheap RG8 from Amazon.

[nokones]

Tune the antenna for 465 Megs if you intend to transmit to repeaters and direct (simplex) to mobiles.

[LeoG]

On 11/3/2024 at 11:42 PM, WRUE951 said:

Did a bird hit your antenna. 

No.  Wind gust.  Crap.

 

An hour later.  I resupported the triangles.  The top one failed.  Put a dadoed gusset on both.  In a couple weeks I won't need this mast other than for the cell phone booster antenna.