• Mobile App For Android Now Online!

    Download it here. The app is searchable in the Google Play Store under Sailboat Owners.

    Sorry iPhone/iPad users, we are still waiting on Apple. :(

    Click the X in the upper right corner to make this go away

VHF antenna problem

Aug 21, 2020
13
Catalina 275 Coffs Harbour
Good news - I found the problem and have fixed it. The problem was the PL259 connector that attaches to the back of the radio. Whoever fitted that connector messed up as there was a direct connection between the shielding and inner core. I resoldered a new one and received a 5 out of 5 radio check. The reception was also noticeably louder and clearer.

You may well ask why I didn't realise this earlier (since that was my original suspicion), and that would be a good question. It all stems back to my original incorrect assumption that there should be NO electrical connection between the shielding and the core. This came from a video demonstrating how to solder a new PL259 connector, suggesting you should test your work by using the continuity test on the multimeter to check for an open circuit between the centre pin and the outside of the connector. Obviously, that person was testing a cable that wasn't connected to an antenna. Now that I know about the loading coil, I should have instead been measuring the resistance. When
I cut the suspect connector off the cable I made the real error - instead of retesting the plug, I repeated the continuity test on the exposed wire. Because it returned the same result I assumed the plug was not the problem, and that another issue existed somewhere up the cable.

With the better understanding I know have (thanks to you all), I now see that measuring the resistance in the first place would have revealed that yes there was a problem, and re-measuring it on either the severed plug or the exposed cable would have identified the problem immediately. I am very sorry it took so long to reach this conclusion and am extremely grateful for all of the suggestions offered above. As well as fixing the problem, I have learned a lot in the last couple of days!
 
Oct 22, 2014
14,233
CAL 35 Cruiser moored EVERETT WA
@dleckenby Do't beat yourself up too much. For most of us this is a learning experience.

That is the benefit of this forum. The sharing of knowledge and experience, even if we have different boats and different back grounds.

Congrats. Now you can pay it forwards.
Fair winds and clear signals.
 
Aug 21, 2020
13
Catalina 275 Coffs Harbour
You mentioned you checked the PL259 connector. How many do you have? On my C30 I have 4. One at nav station where radio is installed, 2 at base of mast with female - female connector and one at the antenna.
When I replaced my radio a couple of years ago I had the same symptoms. Since I had installed two of the crimp connectors, nav station and 1 at the base of mast, I figured I did a poor install and changed them one at a time. Finally I changed the 2nd one at the mast base. This one had been installed by the yard when I first put the mast up after buying the boat.
That was the bad one and I'm glad it was or I would have had to go up the mast.

Moral of that story is connectors are relatively cheap. Just go down the line and replace. I used crimp connectors with plans to go back and install soldered connectors.

BTW, my C30 has internal halyards. I pulled the halyard exit block out to get access to the mast base connectors.
Thanks for that suggestion. I found there was a join in the cable inside the mast at the base. It had originally been wrapped in self-amalgamating tape, but someone had opened the connector which of course broke the tape seal. The connector still looks OK, but I now know to replace the tape to avoid this becoming the next point of failure.
 
Jun 11, 2004
1,082
Oday 31 Redondo Beach
Good news - I found the problem and have fixed it. The problem was the PL259 connector that attaches to the back of the radio. Whoever fitted that connector messed up as there was a direct connection between the shielding and inner core. I resoldered a new one and received a 5 out of 5 radio check. The reception was also noticeably louder and clearer.

You may well ask why I didn't realise this earlier (since that was my original suspicion), and that would be a good question. It all stems back to my original incorrect assumption that there should be NO electrical connection between the shielding and the core. This came from a video demonstrating how to solder a new PL259 connector, suggesting you should test your work by using the continuity test on the multimeter to check for an open circuit between the centre pin and the outside of the connector. Obviously, that person was testing a cable that wasn't connected to an antenna. Now that I know about the loading coil, I should have instead been measuring the resistance. When
I cut the suspect connector off the cable I made the real error - instead of retesting the plug, I repeated the continuity test on the exposed wire. Because it returned the same result I assumed the plug was not the problem, and that another issue existed somewhere up the cable.

With the better understanding I know have (thanks to you all), I now see that measuring the resistance in the first place would have revealed that yes there was a problem, and re-measuring it on either the severed plug or the exposed cable would have identified the problem immediately. I am very sorry it took so long to reach this conclusion and am extremely grateful for all of the suggestions offered above. As well as fixing the problem, I have learned a lot in the last couple of days!
Well I certainly learned a few things from this thread. Thanks for posting the initial problem.
 
Sep 25, 2008
5,975
Alden 50 Sarasota, Florida
Good news - I found the problem and have fixed it. The problem was the PL259 connector that attaches to the back of the radio.
Thanks for acknowledging those who spent the time, albeit small, to suggest fixes. All too often, people come here seeking help and never acknowledge or thank anyone or tell us your success. Doing as you did might serve as a good example for others and in turn motivate others to help.
 
Sep 25, 2008
5,975
Alden 50 Sarasota, Florida
No. That won't check power output or VSWR.

Ken
Ken
I think you are looking at the wrong thing - the link is an SWR meter although it wont read output power with any precision. My only criticism of this meter is that I couldn't find what frequency range it can be used within - A HF SWR meter wont work for VHF and vise versa. As it doesn't specify, I infer it is pretty unreliable
 
Jan 25, 2011
2,186
S2 11.0A Anacortes, WA
A little sleuthing seems to say this is for CB radios..27MHZ. Marine is in the 160Mhz area. SWR is just a ratio. If the radio and gain control can put the needle full scale, it should work...
 
  • Like
Likes: jssailem
Aug 21, 2020
13
Catalina 275 Coffs Harbour
What made you suspect the connector thus cutting it off?
Initially it just looked suspect. The shielding was exposed and frayed immediately behind the connector, so I decided that replacing it was a relatively simple thing to try. I watched a few YouTube videos to learn how to fit a new connector and one of them suggested the test with the multimeter. That's where I went off on a bit of a tangent as detailed above :(
 
Feb 17, 2006
4,992
Lancer 27PS MCB Camp Pendleton KF6BL
That was the correct course of action. Unfortunately, many who work on RF cables do not seal them properly with dual wall / double wall heat shrink tubing. It is very important after working on connectors to protect them. Given time, as noted above, the cable outer sheave will eventually pull back exposing the shield. This will allow contaminates to enter and break down the shield wires.

So lesson to be learned here; purchase a 3:1 dual wall / double wall heat shrink tube and whenever you have to change any kind of connector, make sure you protect the opening as best you can.
 
  • Helpful
Likes: jssailem