Combining Different Coax

[MikeHoncho]

Just finished my two week trip into the Canadian Gulf Islands and noticed I kept getting a error code saying my antenna VSWR is high/background AIS noise is high. I use a electric splitter for VHF and AIS to a single antenna. I have a coax connection in the cabin under the mast step (cabin stepped) that I found very corroded connections (two male with barrel connector). I cut out the connectors and resoldered them as a temporary fix. It eliminated the error but I noticed I had poor VHF performance (not able to hear weather or normal traffic ) I am going to replace the old connectors with new solder connectors but I would like to replace the coax also. I will not be replacing the section within the mast due to logistics but would like to replace the section within the boat. I'm looking at LMR- 400. Any issues with combining old with new other than performance loss of the old? Which connectors would your recommend.

[deblen]

Originally Posted by MikeHoncho

Just finished my two week trip into the Canadian Gulf Islands and noticed I kept getting a error code saying my antenna VSWR is high/background AIS noise is high. I use a electric splitter for VHF and AIS to a single antenna. I have a coax connection in the cabin under the mast step (cabin stepped) that I found very corroded connections (two male with barrel connector). I cut out the connectors and resoldered them as a temporary fix. It eliminated the error but I noticed I had poor VHF performance (not able to hear weather or normal traffic ) I am going to replace the old connectors with new solder connectors but I would like to replace the coax also. I will not be replacing the section within the mast due to logistics but would like to replace the section within the boat. I'm looking at LMR- 400. Any issues with combining old with new other than performance loss of the old? Which connectors would your recommend.

How did the indoor conn. get corroded? Did water get in mast coax & chase down the mast to this conn.? If yes,you will need to replace mast coax.& fittings.

Personally,I would use RG58CU from joint to radios-insignificant loss for that short distance.

Can you look inside "electric splitter" for corrosion?
Cheers/Len

[MikeHoncho]

Originally Posted by deblen

How did the indoor conn. get corroded? Did water get in mast coax & chase down the mast to this conn.? If yes,you will need to replace mast coax.& fittings.

Personally,I would use RG58CU from joint to radios-insignificant loss for that short distance.

Can you look inside "electric splitter" for corrosion?
Cheers/Len

40+ year of humidity, condensation and mast step leaks......The coax in the mast will not be replaced unless it totally fails due to access and the extensive through step seal/system I installed several years ago or until I unstep the mast. The splitter is isolated at the AIS/VHF with no possibility of water intrusion. Appreciate the input on the coax. The run is about 25 ft.

[wholybee]

Did I read that you soldered the 2 pieces of coax without connectors? Or that you reused and resoldered the old connectors? In either case, I don't expect that would work very well. Something to know about VSWR. A high VSWR means that there is certainly a problem. But, a low VSWR does not indicate that there is no problem. You can have a VSWR of 1:1, and still have no energy being transmitted at all, or that any signal will be received at all.

If _any_ water got to the shield, the whole coax needs to be replaced. If the corroded bit is the shield, the whole coax needs replaced. If the water only got into the connector and did not reach the coax, then the coax can be reused by just cutting off a couple inches and installing a new connector.

The splitter needs to be designed for this specific purpose. I assume you know that and it is. But just in case, The "splitter" needs to really be a switch that switches 100% to the VHF when you transmit on VHF, and 100% to the AIS when AIS transmits. It is only a true splitter when both are receiving. If you have a cheap general purpose splitter (even an electric amplified one) then you invite all sorts of issues.

25ft isn't long enough to justify LMR400. But, if you want to replace the whole run, know that LMR400 is more difficult and more sensitive to correct installation. I use LMR400 with great results, but I always recommend hiring a pro that has worked with LMR400 over a self install.

[barnakiel]

Coax can be combined.


But, how do you know if the loss is within the piece in the cabin ?? I would bet the antenna and mast coax are your culprit.And esp look at the antenna to coax at the mast-top connector - this is where most of the time one can find water ingress amd hence plenty of signal loss.


btw 2 the piece in the mast is also the longer of the two arms - many masts stan 10m and taller, but few cabins are longer than 4-5m.


cheers,
b.

[deblen]

https://www.cruisersforum.com/forums...es-287872.html

[stormalong]

As long as the coax that you use is 50 ohm you are OK. LMR400 is a foam core dielectric and should not have tight bends. For a temporary fix I wouldn't bother with LMR400. When it comes time to rewire the mast a single length of rg213 would be my recommendation. Davis RF sells a marine grade (tinned conductors) version.

Your present situation is why I suggest a single length - no connectors under the mast. PL-259s into a barrel connector are fine until they get wet and then you have corrosion and problems. Just have a piece long enough to reach the radio plus a couple of feet. The extra length allows you to cut off the pl-259 on the radio end the next time you drop the mast. Just solder on a new one. Also do not use a "labor saving" Shakespeare type pl-259. Use a good Amphenol solder on, or if you have a proper crimping tool you can use a crimp on pl-259 that is silver plated. You can't go wrong with Amphenol.

[MikeHoncho]

Originally Posted by wholybee

Did I read that you soldered the 2 pieces of coax without connectors? Or that you reused and resoldered the old connectors? In either case, I don't expect that would work very well. Something to know about VSWR. A high VSWR means that there is certainly a problem. But, a low VSWR does not indicate that there is no problem. You can have a VSWR of 1:1, and still have no energy being transmitted at all, or that any signal will be received at all.

If _any_ water got to the shield, the whole coax needs to be replaced. If the corroded bit is the shield, the whole coax needs replaced. If the water only got into the connector and did not reach the coax, then the coax can be reused by just cutting off a couple inches and installing a new connector.

The splitter needs to be designed for this specific purpose. I assume you know that and it is. But just in case, The "splitter" needs to really be a switch that switches 100% to the VHF when you transmit on VHF, and 100% to the AIS when AIS transmits. It is only a true splitter when both are receiving. If you have a cheap general purpose splitter (even an electric amplified one) then you invite all sorts of issues.

25ft isn't long enough to justify LMR400. But, if you want to replace the whole run, know that LMR400 is more difficult and more sensitive to correct installation. I use LMR400 with great results, but I always recommend hiring a pro that has worked with LMR400 over a self install.

I was on anchor. I removed the connectors and reinstalled and soldered the core to the connector like it was suppose to be, I did not solder the shield wire which I know is not a good think but I was using a bic lighter. Appreciate the input on moisture in the coax. i have no idea if there is as its in the mast. I cut back a section on the boat side and it the core was shine\y and did not look corroded. I did not cut back the mast side. It is a little shorter and I did not have enough room to resolder with a lighter. I'll cut it back when I get a new connector and use a soldering iron or torch.

[MikeHoncho]

Originally Posted by barnakiel

Coax can be combined.


But, how do you know if the loss is within the piece in the cabin ?? I would bet the antenna and mast coax are your culprit.And esp look at the antenna to coax at the mast-top connector - this is where most of the time one can find water ingress amd hence plenty of signal loss.


btw 2 the piece in the mast is also the longer of the two arms - many masts stan 10m and taller, but few cabins are longer than 4-5m.


cheers,
b.

I don't but If I'm going to change out the connectors, I'd like to change out the coax that I can. I have mast steps so I'll take a look at the top connector at the antenna when I can.

[S/V Illusion]

Originally Posted by MikeHoncho

I know is not a good think but I was using a bic lighter.

You didn’t solder anything; you melted some solder on a pin with a wire in it.

Not a good idea for something on which the safety of people might depend in an emergency.

[wholybee]

Originally Posted by MikeHoncho

I was on anchor. I removed the connectors and reinstalled and soldered the core to the connector like it was suppose to be, I did not solder the shield wire which I know is not a good think but I was using a bic lighter. Appreciate the input on moisture in the coax. i have no idea if there is as its in the mast. I cut back a section on the boat side and it the core was shine\y and did not look corroded. I did not cut back the mast side. It is a little shorter and I did not have enough room to resolder with a lighter. I'll cut it back when I get a new connector and use a soldering iron or torch.

This is exactly why I recommend pros install coax. It's a simple and understandable mistake to use a lighter. But, _good_ soldering is difficult. Most people need one-on-one instruction, and everyone will need practice. And soldering something like a coax connector, the run of the mill soldering iron won't work. And a flame will NEVER work.

If you want to do this yourself, buy 10 or 15 connectors. Buy at least a 150W iron, if not larger. And practice installing all but the last 2 connectors on some scrap coax. Be meticulous following the instructions that come with the connector regarding measurements stripping the coax.

If you are not willing to do that, hire a pro. After buying 15 connectors, some scrap coax, and a decent iron, the price difference probably isn't that great.

[MikeHoncho]

Originally Posted by S/V Illusion

You didn’t solder anything; you melted some solder on a pin with a wire in it.

Not a good idea for something on which the safety of people might depend in an emergency.

Take it easy, I was at anchorage in the middle of a two week trip with a back up hand held vhf. The solder joint effectively resolved my AIS issue as a temporary repair. My OP asked about connectors and coax so it’s fairly obvious I’m going to replace it all (except for the mast until I unstep it).

[MikeHoncho]

Originally Posted by wholybee

This is exactly why I recommend pros install coax. It's a simple and understandable mistake to use a lighter. But, _good_ soldering is difficult. Most people need one-on-one instruction, and everyone will need practice. And soldering something like a coax connector, the run of the mill soldering iron won't work. And a flame will NEVER work.

If you want to do this yourself, buy 10 or 15 connectors. Buy at least a 150W iron, if not larger. And practice installing all but the last 2 connectors on some scrap coax. Be meticulous following the instructions that come with the connector regarding measurements stripping the coax.

If you are not willing to do that, hire a pro. After buying 15 connectors, some scrap coax, and a decent iron, the price difference probably isn't that great.

Again…….at anchor on a two week trip. It temp. resolved my AIS issue. I will defiantly be doing it myself and will buy extra materials to practice. I have the equipment to do it while in slip.

[BocaIII]

lmr400 is over kill for short run of coax
RG8x is fine for run less than 10ft, if longer than 10ft RG213 is better
no issue combining different coax types
splicing coax by soldering center conductors and braid works well so long as you have the skill level to do it properly. Otherwise, use barrel connector with dielectric grease for corrosion protection.
good luck
Capt. Jack
W4GRJ

[Jammer]

Originally Posted by MikeHoncho

I am going to replace the old connectors with new solder connectors but I would like to replace the coax also. I will not be replacing the section within the mast due to logistics but would like to replace the section within the boat. I'm looking at LMR- 400. Any issues with combining old with new other than performance loss of the old? Which connectors would your recommend.

LMR-400 has an aluminum shield which is susceptible to corrosion. Use RG-213 instead unless you need the bend radius and smaller size of RG-58 for a short part of the run.

Use type N crimp connectors for connections at the mast step etc. as they are more water resistant than SO-239/PL-259 connectors.

For short sections of coax where there is good enough access to allow the connectors to be installed before the coax is run, purchase the coax with the connectors already installed from a place like Pasternack. They will do a better job than anyone can possibly do aboard a boat.