AIS Antenna Troubleshooting - Poor VSWR possible causes?

[Tessellate]

Is there anything else I can do to troubleshoot AIS antenna issues?

I got a VSWR meter and it said I have bad VSWR, which isn't very helpful actually since I already knew that from the Raymarine AIS software's report (images attached). But the meter confirms the Raymarine reading is correct. I also bought a dummy load to test the Raymarine AIS-650 unit, and that tested perfectly (1.01 VSWR, 2.22 watt) so the issue isn't with the AIS unit.

This is my 2nd Shakespeare AIS-5250 antenna. It's a dedicated stern mounted AIS antenna.

• I've replaced the connector 3 times, with 2 types of PLB-259 connector.
• The 1st antenna had VSWR issues. The 2nd antenna (brand new) worked for 2 months, then had VSWR issues.
• The antenna, cable and connector look perfect, undamaged, and dry.
• One new connector worked for one day with 2.0 VSWR (still not perfect) and then deteriorated to 4.0+ VSWR.

Shakespeare hasn't been helpful with tech support. They've offered a warranty return but never connected me to anyone technical to help troubleshoot. I don't want to keep replacing the antenna though if that's not the issue.

Is there anything else I can test / look into? Shakespeare said electrical interference would only be an issue within 3' of the antenna itself. I don't have any wires there, and my Starlink is 3' away.

The weird thing is how the new antenna worked for a while and then started emitting high VSWR errors. The AIS still works for receiving and transmitting (but with reduced transmit range) but emits annoying recurring beeping alarms on our Raymarine chartplotter, which can't be permanently disabled.

[Wotname]

The problem will be the coax or the connectors or the actual antenna. To isolate, insert the VSWR meter at various points in the transmission path.

Usually start at the output of the transmitter and finish at the input of the antenna. Use the 50 ohm dummy load as required.

[Tessellate]

Originally Posted by Wotname

The problem will be the coax or the connectors or the actual antenna. To isolate, insert the VSWR meter at various points in the transmission path.

Usually start at the output of the transmitter and finish at the input of the antenna. Use the 50 ohm dummy load as required.

Yes, but the antenna has only one connection point and I've already tested that with the VSWR meter and redone the connector 3 times. The antenna comes with an integral RG-58 coax cable (ie, no connector at the antenna side) and I was careful not to twist that upon install.

The connector I've redone 3 times could be the culprit - the first time I might have done a bad solder job. So the next 2 times I used a Shakespeare PL-259-CP-G solderless connector. One of them initially worked, but then deteriorated. So I'm not sure how to determine if the connector is at fault or not. At $15-20 a pop, these connectors are getting expensive...

[wholybee]

It is very easy to poorly install connectors, and there are also quite a few poorly made connectors. Symptoms are of course high VSWR, and often don't show up right away. I often recommended that boat owners seek professional help to install the connectors and coax for this reason. It isn't that a skilled person can't figure it out and get it right, but often they won't and will believe they did a fine job.

Shakespeare connectors aren't usually very good. The screw on are the worst of the worst.

Amphenol is a good brand:
https://www.mouser.com/ProductDetail...Gdh2U1MQ%3D%3D

[Statistical]

So the next 2 times I used a Shakespeare PL-259-CP-G solderless connector. One of them initially worked, but then deteriorated.

To be blunt those are absolute garbage connectors. It working initially and then going to **** is pretty typical for these low quality screw on connectors.

The gold standard for connectors is soldered both the center pin and the shield. However it is very tough to do it right. You also want a large heavy soldering iron because you want a lot of thermal mass. Most boat owners simply never get the amount of soldering skill required to be consistently good at that and they don't have the right tools. The shield is the hard part. Honestly I would just drop this from consideration unless you already have exceptional soldering skills and equipment from non-boat work.

One step below that is a combination solder and crimp. The center connection is soldered and the trickier shield is crimped into place. It is easier for those with less soldering experience to consistently get a good connection using this type of connector. You might need to do a practice run on a test cable but most people with a little effort can make a solid connection.

One step below that and likely the best option for a DIYer with no soldering skills is all crimp. While an all crimp connection may not be the gold standard it is easier for a DIYer to consistently produce a "silver" standard result. With solder even just center pin solder results are a lot less consistent. The downside is these connections usually required a braided center core which is uncommon on boats.

8000 steps below that is any screw on connector from any brand ever made since rf became a thing. They are just ****. Nobody anywhere in RF profession uses them for anything. The only reason they exist is because if brands didn't offer it they would lose sales to brands that do because most consumers just want the cheap easy option with skills or tools required.

To put comparative numbers on it in terms of connection quality
All solder - 10
Crimp & solder - 9.8
All crimp -9.5
Screw on - 0.1

[Statistical]

One thing I would add is with crimp and solder connectors you don't even need a soldering iron a butane torch will work fine.

Cut the center pin a half inch or so longer than needed. Assemble the connector and crimp the braid. You will now have a center conductor which extends beyond the center pin. Heat the wire with the torch and apply solder to the center pin. It will have a cup like shape. Once the solder runs you are done. Wait for it to cool keeping the cup facing up. Then snip the excess wire flush with the pin.

[Wotname]

I endorse the above posts about connector quality.

I'll add that a solder / clamp connector system also works well if you don't have access to a suitable coax crimp tool. The centre pin is soldered (sometimes crimped) and the outer braid is clamped (not crimped or soldered).

I suggest the Amphenol 182103 as a reasonable quality clamp connector and should be available worldwide.

https://www.amphenolrf.com/182103.html

Assembly (the link shows a BNC connector but the UHF connector is similar)

https://s3-us-west-2.amazonaws.com/c...amp-Solder.pdf

[Tessellate]

Thanks, sounds like I should suspect the connector first and foremost.

I have successfully soldered before (VHF connections) but this time I guess I didn't do a great job. It worked for 2 months though (a Shakespeare PL-259-G). Upon disassembly the solder fell off the braid. So I didn't get enough solder into the braid holes, or didn't get the connector hot enough. I've watched many Youtube videos plus marinehowto.com's guide on antenna connectors. But I typically borrow a soldering iron from a neighboring boat, and the one I borrowed wasn't very good (dirty tip, not cleaned in a long time probably) and I was working in a cramped space in the aft berth.

So I figured I'd try the Shakespeare crimp on (screw on?) CP-G because they're the antenna manufacturer, and why would they sell a connector that doesn't work well right? I have heard good things about Amphenol and other brands, but we're cruising in a relatively remote area and stores don't carry those. Marine stores carry Shakespeare and Sea-Dog connectors (which are cheaper and look even lower quality). I can order the other brands online, even Amazon, but it will take multiple weeks to receive.

The CP-G connectors were appealing in their simplicity. And the Amazon reviews of it are actually quite good (mostly 5 stars). I'm not sure if it falls under "crimp on" or "screw on". Shakespeare calls them "center pin" solderless connectors, but some sites label them as "crimp" connectors. @Statistical, per your ranking would you put that in the 9.5 (95% of best) category?

They have 4 metal arms which are pressed into the braid through the cable jacket, and a tiny gold pin which presses into the center conductor. Once I received the connector I felt that the design is much more hacky and tenuous than I expected, but in theory it should work. The first one I did, I crimped the arms a bit too much and they penetrated to the core, shorting out the connector. The 2nd one I did very carefully, just as perfectly as the Shakespeare engineers in their YouTube video, but it only had decent VSWR for one day.

It would be nice to hire a professional, but they're not so easy to find in Southeast Alaska. I will look into crimp and solder connectors or the Amphenol clamp on.

[Jammer]

You're getting good advice. Yes, the no-solder no-crimp Shakespeare connectors are complete junk. Yes, it is hard to solder the connectors that are designed for that -- you need the correct solder, the correct iron, and good technique. I can do it (I've soldered stuff for years) but prefer not to as I believe the crimp connectors are more reliable.

I would suggest crimp connectors. DX Engineering sells the connectors and reasonably priced crimp tools. It's what I use.

https://www.dxengineering.com/parts/aml-182100-4

https://www.dxengineering.com/parts/dxe-ut-crmp2-8x


It is also possible that the antenna actually is shot -- or intermittent -- it happens.

You won't get a fantastic vswr with an end-fed half wave antenna like that. Those are dependent on their environment and feedline for a counterpoise. In theory they don't work at all but in practice they do OK.

[S/V Illusion]

How did you weather-proof the exterior antenna PL259?

[Statistical]

Originally Posted by Tessellate

The CP-G connectors were appealing in their simplicity. And the Amazon reviews of it are actually quite good (mostly 5 stars). I'm not sure if it falls under "crimp on" or "screw on". Shakespeare calls them "center pin" solderless connectors, but some sites label them as "crimp" connectors. @Statistical, per your ranking would you put that in the 9.5 (95% of best) category?

Those are screw on and junk. Calling it crimp would be false advertising IMHO but lots of stuff is mislabeled. Crimp on will require you to use a crimping tool which looks similar to the ratcheting crimpers used for power cable lugs but with a different head.

Marine How To has a good guide:
https://marinehowto.com/easy-vhf-terminations/

If you are handy with a soldering iron I would go that route. Solder for center conductor and crimp (using a crimping tool) for the braid. It is what I use. The alternative is as Jammer suggested all crimp. The connector will use two crimps one for the center conductor and one for the braid. All solder (solder braid and also solder center conductor) is also an option to but really tough to get right. The braid is very challenging unless you do 20 of these a week.

No matter what the company calls it (screw on, clamp on, tooless, etc) if it doesn't require some tool for both points then IMHO it is junk.

The three good options are:
solder center & solder braid (tough to get right)
solder center & crimp braid (marine how to guide above)
crimp center & crimp braid (jammer link above)

Once you get a good connection test it and then heat up the heat shrink tubing (remember to slide the tubing on before starting). Use the good marine glue kind. This will prevent water from entering between the cable and connector. Then cover the joined connectors (cable connector to antennas connector) in waterproof self amalgamating tape. Just test it before doing all that.

[deblen]

OK This suggestion for DIY PL259 install on RG 213U,RG8X or RG 58CU good quality marine coax is going against most of the previous,proper, correct methods.
I used it for many years on commercial fishboats,mainly because the local windy,stormy,wintery conditions made soldering,while up a mast, extra difficult.
My connections work well for many years & gave excellent VSWR on my Bird 43 meter.
Try it yourself-you will like it


RG213U & hi quality PL259
Cut coax in to center conducter at 3/4" back from end of cable & remove all insulation.

This leaves 3/4" of center conductor(only) exposed.
Carefully cut outer sheath back 1/4",exposing 1/4" of braid.
Fold braid back over remaining outer sheath.
Disassemble the PL259 & slide it's outer part onto cable.
Twist the stranded coax center conductor tightly & insert the RG213U into PL259 carefully so that ALL strands of center conductor enter the center pin.
Using slip joint pliers ,thread the PL259 on over the braid covered outer sheath as far as possible-approx 3/8" .It is OK if some tightly twisted center conductor still shows where it enters center pin.

All 1/4" of braid will be fully covered by PL259 threads & PL259 will be mechanically strong.
Note: with some RG213U,you MAY have to trim a FEW strands of braid,or taper the cable sheath slightly to get threading started.

The center conductor will project out of the hollow center pin 1/4" or so.
Spread out & bend the strands of center conductor down over center pin.
The PL259 is now ready for use-no soldering or crimping required.
If weather proofed properly,it will last as long & perform as well as a properly soldered PL259. Try it yourself



RG8X You must install a UG176 bushing on over the braid first-otherwise proceedure is similar to RG213U.
RG58CU-You must install a UG175 bushing over braid first.
SOME trimming of braid or tapering of sheath MAY be required to get bushing started. Twisting bushing clockwise may help.
Do not use a UG 176 bushing on RG58CU.It will be too loose & VSWR will suffer.


NOTE: You must use 2 pairs of pliers to firmly tighten the PL259 on over the UG175/UG176 bushings,or they may loosen over time & VSWR will suffer.


Waterproofing:
ALWAYS use a drip loop to shed water from chasing cable into connections/joints.
Wrap rubber conforming tape over complete joint with at least 1" overlap out over cable sheath. Start winding this tape over coax first,then up over mechanical joiners,winding in the "uphill" direction,so that tape laps will shed water like roofing shingles,& continue winding out over an inch or so of "uphill coax.

Mold the tape with your hand.
I recommend coating this whole taped assembly with liquid tape.


Some pics of typical conn. & bushings.
https://www.rfparts.com/pl259-amp.html



Cheers/Len

[Jammer]

Originally Posted by S/V Illusion

How did you weather-proof the exterior antenna PL259?

There isn't one. His antenna came with an integral cable that reaches all the way to the AIS.

[deblen]

RG213U.RG58CU & RG8X will not stand much external heat.
Relatively mild heat from an engine compartment,exhaust,etc. will cause the VSWR characteristics to change,ruining the coax exposed.
You can't always see this damage by looking at coax exterior.
Sometimes you can feel a slight hardening/stiffening of coax.
Take note of the area/wire/paint color/etc for clues of heat.
Cheers/Len

[S/V Illusion]

Originally Posted by Jammer

There isn't one. His antenna came with an integral cable that reaches all the way to the AIS.

What seems confusing is that he said he replaced the coax connector 3 times.

Even a factory cable connection can fail if not properly done and weatherproofed effectively and this whole problem reeks of that symptom.