How to improve marine VHF SWR?

[harringtondav]

When we bought our boat 22 yrs. ago, before cell phone coverage improved to today's stds, I bought a Shakespeare SE2510 VHF radio. I wasn't transmitting clearly, or at all according to my boating friends. I sent it back to Shakespeare who returned it as OK. I bought a SWR meter, and the ratio was too high. Can't remember the exact ratio. I went from a short, bare 3-4' whip antenna to an 8' antenna. The SWR improved - a little, but still above the recommended max.

I've got the short antenna back on. It works fine for close range hailing lock masters, and listening to WX and the local Artco terminal barges working with the long distance barge tows. I don't need much more. But I've always wondered if there is a way to reduce my SWR down to recommended levels.

Any suggestions?
Thanks, Dave

 

[alldodge]

Worth listening in to see if there is a way. I to have a SWR meter and tried that some time ago, its actually still on the boat under some junk, noticed it a week or so ago.

Mine also showed it higher (don't remember how much) but there is no tuning I have ever found. The best improvement for VHF is the height of the antenna and the db gain. Mine seems to have no issue, and antennas are Shakespeare 5225 8 footers with 6 db gain, mounted on top my radar arch, so up probably 20 feet total

dingbat might have an answer

 

[StingrayMike]

VHF's are point-point, so height of the antenna effects range, but the biggest effect of SWR is cable type, length, and connections. Each PL connection will drop the DB by .5. Not knowing what you have for connections and type of cable used, it would be hard to tell, as well as what the radio is actually putting out.
ex of what I have seen :

48' sport fish, with 8' antennas, only PL connections at the radio, (antenna is hardwired), I have seen SWR <.5 watts, Xmit pwr >25 watts.
and
80' sportfish same antennas and radio SWR < 2 watts, xmit pwr 19.5 watts.

difference is length of cable

under 2 watts SWR is considered within industry standards.

8x is a suitable cable for impedance matching.

also not all watt meters are the same. I use a BIRD watt meter for work, as well as a small shakespheare that you can get at any marine store/ amazon for a backup the readings are different.

corrosion, bad connections, compromised cable insulation can cause high SWR, or even a bad radio (have seen out of the box failures)