Marine Electronics Forum - VHF Issues. HELP PLEASE!!

I've only been getting10-12 miles of usable range (I used to get 20+ miles cleartx/rx)from my radio/antenna setup.So I just did a test with a Shakespeare ART-2 Antenna/Radio tester on my Icom-422 and8ft Shakespeare Galaxy. As I suspected, the radio is fine but the antenna or coax seems to be the problem.

I get 22 watts transmit power from the radio (not the best, but ok for now). But the antenna gives me a VSWR reading of about 3:1 instead of 1:1 or 2:1. I had an oldnick in my coax so Icut and replaced myold solderless brass RG58 connectors two weeks ago (that probably accounts for the 3 watt loss I'm getting). I've checked the coax and see no obvious nicks or cuts. I want to change the coax connector to my radio anywaybecause it seems dodgy.My coax runs right next to my radio power cables.

My question: Is there anything else I should look at or change that would account for my poor radio performance?

Definitely sounds like a connection issue. I would replace the entire coax cable if possible.

Do you have extra coax cable in your run and if so did you coil it. If so that could account for the loss.

twotems - 8/28/2006 7:15 AM But the antenna gives me a VSWR reading of about 3:1 instead of 1:1 or 2:1.

My coax runs right next to my radio power cables.

My question: Is there anything else I should look at or change that would account for my poor radio performance?

A SWR on a VHF is not the same as on a CB or other radio, so forget the SWR ratio - yours is fine.

Normally not a problem with the coax running next to your power cable. If you think it might be a problem, pull your power cables and twist them, then run the twisted wires back to the radio.

IMO the culprit is your connection. Replace the connector on your cable with a PL-259 connector and be careful to get the ground shield correct - one errant wire from it will seriously degrade your signal.

FL the instructions on the tester state that a VSWR ratio above 3:1 indicates a problem with the coax or antenna, so I'm only following Shakespeare say. Pirate, the coax isn't coiled and I have about 8ft of cable in total which worked fine until now. I'm leaning towards the connector too. Any more suggestions?

A SWR on a VHF is not the same as on a CB or other radio, so forget the SWR ratio - yours is fine.

BS. I said BS. Of course it's the same. It's a ratio of "forward" power to "reflected" power. It's the same throughout the radio spectrum. The more "reflected" power, the lower the transmitter output power. If the VSWR gets TOO high, the radio's protection circuits will (should) shut the transmitter down.
There IS a problem. 3:1 is NOT acceptable. Fix it.

Shakespeare's assertion that 3:1 is acceptable is a cop out for poor antennas. Strive for 1.5:1 or lower. 2:1 should be a max. Test a new antenna before installing it to make sure the antenna is good right out of the box.

I too suspect the connector. Be very careful when replacing these. I would also check to see if there is any physical damage to the antenna. Sometimes the whipping action caused by the waves or if your antenna hit anything (garage, bridge) will crack or splinter the antenna. Assuming it is a fiberglass antenna not a stainless whip.

Shakespeare's assertion that 3:1 is acceptable is a cop out for poor antennas. Strive for 1.5:1 or lower. 2:1 should be a max. .

Shakespeare don't claim 3:1 is acceptable. They state that anything close to or above 3:1 is poor and the coax and antenna must be checked. Their recommended range is 1:1 or 2:1. :thumbsup:

There IS a problem. 3:1 is NOT acceptable. Fix it.

Hmmmm. How do you do that?

First Light - 8/29/2006 5:03 PM

There IS a problem. 3:1 is NOT acceptable. Fix it.

Hmmmm. How do you do that?

Start the cheap way, by making sure there are no cuts and nicks in the coax. Step 2 is to solder on on a new PL259, or have an experienced person do it for you.

Look at the shielding when you cut off the old connector. Salt water can (and will) wick up the shielding for quite a distance -- several feet, sometimes. Cut the outer vinyl carefully with a single-edged razor blade until all the green gook is gone. THEN solder on a new connector. You'll be able to tell if the coax is good or not.

Like the others, my guess, with a 3:1 VSWR, is all that's wrong is in the connector.

Once you're sure the PL259 is good, test the antenna again. If the VSWR is still poor, then it's time for a new antenna.

First Light - 8/28/2006 9:36 AM

A SWR on a VHF is not the same as on a CB or other radio, so forget the SWR ratio - yours is fine.


WOW! Dead wrong! Voltage Standing Wave Ratio (VSWR or SWR) is the same on any transmitting device wether it is a VHF, CB, RADAR, or any other. Most boaters do not have a CB and cannot check their radar VSWR. Reflected power is the #1 cause of reduced transmit capabilities. VSWR/SWR is the only means of measuring the efficiency of your VHF. 1:1 is perfect, but almost impossible to reach, 1:1 to 2:1 is good, 2:1 to 3:1 is fair and steps should be taken to improve, 3:1 and higher is poor and must be corrected if you want any reliable communications.

The VSWR/SWR is not applicable to your receive side, however the condition of your coax/connections does play a big part. Receiver sensitivity (adjusted internally in your VHF) is the biggest factor on the receive side, but it is not easily adjusted. Most HAM operators would have the equipment and the know how to adjust the sensitivity.

So, bruce - you didn't tell us how to adjust and improve the SWR on a VHF?

First Light - 8/30/2006 1:36 PM So, bruce - you didn't tell us how to adjust and improve the SWR on a VHF?

It seems pretty clear by the answers on here and by what Shakespeare say. Check connectors, coax and the antenna itself. ;?

Thanks for all the help. :thumbsup:

twotems - 8/30/2006 9:02 AM


It seems pretty clear by the answers on here and by what Shakespeare say. Check connectors, coax and the antenna itself. ;?

Thanks for all the help. :thumbsup:

:thumbsup:

From your description the problem could be the connector, the cable, or the antenna itself. Unfortunatly for testing, Shakespeare antennas and cable are one asssembly. Changing the connector is a practical thing to try. Without a TDR instrument (very special RF test gear) to eliminate the cable, it would be necessary to cut the coax at the antenna and install a connector and then test the antenna. ...Then, if it was the cable - not the antenna, you have to install a totally waterproof connector to "splice" on new coax. The (typical) 8' fiberglass antenna can certainly fail internally. It is not just a simple wire, but (depending on the model) constructed with various sections of coax or brass tubes with lots of solder joints. For all practical purposes, if the connector does not fix things, it is new antenna time.

BTW, Standing Wave Ratio (SWR) is SWR... Frequency makes no difference in its effect. 2:1 is a marginal value, 3:1 is bad - whether CB, HAM, VHF marine, etc. Also, some transmitters sense high SWR and reduce the output power to prevent output transistor damage. One more thing. Inexpensive SWR/Power meters are notoriously inaccurate. Most are doing well to be within +- 10%. If the SWR is not 1:1, the reading can be even further off. With a 3:1 SWR the accuracy is likely much worse.

I checked my antenna using an "antenna analyzer" which gives more detailed information than a SWR/PWR meter. It is running 1.2:1... Shakespeare recommends a minimum of 3' (if I recall) of reasonably straight-run coax. After that, you can cut the cable and add the connector. Excess cable will produce a small but defnite loss of both receive and transmit capability. If your cable nick was only in the jacket and no water entered (corrosion) then sealing it is fine and that is not the problem. If the shield, or worse, the dielectric/center conductor exposed, then it could (would?) be a problem.

good luck!

Woody, KZ4AK
NorAn - 85 Albemarle 24

I agree that you need to replace the coax--but you will have a little loss, because you will be adding two PL 259's and a barrel connector at the antenna most likely. The solderless conectors are less than ideal with time.

Unfortunately many marine vhf antennas are not as well made as you would like. I take my MFJ 259B anatenna analyer with me to the store and check the antennas to find the one closest to 1: 1 SWR. ( I have seen some 2.5:1 on the rack). Ideally the antennas would be well tuned and checked at the factory--but unfortuantely that is not the case. Also corrosion takes a toll with time. Most of the cheaper antennas are just soldered wire.

I would just consider going out and buying a new Digital 529 VHF antenna and then you will not have to worry about connectors, loss etc. That way you know that you are good to go! We are talking a safety issue here.

KA6PKB

thataway - 9/1/2006 6:47 PM

I agree that you need to replace the coax--but you will have a little loss, because you will be adding two PL 259's and a barrel connector at the antenna most likely. The solderless conectors are less than ideal with time.

Unfortunately many marine vhf antennas are not as well made as you would like. I take my MFJ 259B anatenna analyer with me to the store and check the antennas to find the one closest to 1: 1 SWR. ( I have seen some 2.5:1 on the rack). Ideally the antennas would be well tuned and checked at the factory--but unfortuantely that is not the case. Also corrosion takes a toll with time. Most of the cheaper antennas are just soldered wire.

I would just consider going out and buying a new Digital 529 VHF antenna and then you will not have to worry about connectors, loss etc. That way you know that you are good to go! We are talking a safety issue here.

KA6PKB

When you buy that Digital antenna, remember to order the cable length you need for your boat. Then you wont have a big coil sitting in your E-Box.

UPDATE: Changed the connector and the radio is perfect now. I bought a Digital from Jim anyway and I'll keep it until my Shakespeare finally dies.

Thanks THT members. :thumbsup:

I don't know nothing from nothing about diagnosiing VHF problems. But I can tell you my story when I've had VHF problems. Personally, I have not had much luck with Shakespear antennas on two different boats. I had all kinds of similar issues with my Icom 402S on my last boat. I couldn't figure it out. I had two different radio guys out to look at it. They re-soldered the connections, moved the power supply, did all kinds of tests, but it never worked to my satisfaction when i was actually on the water. I was never happy with it. It didn't work worth a dime during two separate Bahamas trips, both receiving and transmitting. That's when I had had enough.

I finally replaced the Shakespear Galaxy 8' antenna with a Digital 529VW 8' antenna. Problem solved. My VHF radio worked better than it ever had before. Save yourself some grief and just scrap the Shakespear and replace it with a Digital. You won't be sorry.

Kiki's Ring - 11/17/2006 7:12 PM I don't know nothing from nothing about diagnosiing VHF problems. But I can tell you my story when I've had VHF problems. Personally, I have not had much luck with Shakespear antennas on two different boats. I had all kinds of similar issues with my Icom 402S on my last boat. I couldn't figure it out. I had two different radio guys out to look at it. They re-soldered the connections, moved the power supply, did all kinds of tests, but it never worked to my satisfaction when i was actually on the water. I was never happy with it. It didn't work worth a dime during two separate Bahamas trips, both receiving and transmitting. That's when I had had enough. I finally replaced the Shakespear Galaxy 8' antenna with a Digital 529VW 8' antenna. Problem solved. My VHF radio worked better than it ever had before. Save yourself some grief and just scrap the Shakespear and replace it with a Digital. You won't be sorry.

I've already bought the same Digital and will do so eventually. Meaning, I know the Shakespeare will do something funny in the next few months. In the meantime I've corrected MY errors on that antenna and will give it another chance. :thumbsup:

Twototems- Long ago you mentioned that the 22 watt output was an issue to you. Relax, Powerboat Reports did a test on major brand VHFs not so long ago and determined very few "quality" VHFs had greater than 22 watts and I believe none had the 25 watts they all claimed for factory spec max output.

BTW, the ART-3 will allow you to test reception as well as transmission. True, the ART-3 & ART-2 testers may & usually will vary slightly in readout from tester to tester ( like most thermometers) even after individual "zeroing" calibration each time according to instructions, but are plenty accurate enough for relative analysis, especially if a good base reading is taken & recorded after proper installation of a good product, then compared to future test readings. You can then easily see if the system is degrading before you would otherwise know it & need it. They are great tools, almost must-have.

Indeed, I was getting 22 watts but now it's 25 since I replaced the connector, according to the ART-2. Most importantly I'm receiving very clearly now with no static. I feel that reasonable care needs to be taken for all brands of electronics and frankly I didn't do that as far as my antenna/connector was concerned.