BajaNomad

boosting vhf marine radio wattage

wetto - 4-17-2015 at 08:55 AM

I know the reception would not improve but has any toyed with trying to boost the transmit signal strength to have longer reach?

Alan - 4-17-2015 at 09:08 AM

Handhelds are limited by their wattage but I believe most base units have adequate power. The limiting factor for VHF reach is the curvature of the earth so it becomes more a matter of antenna height.

woody with a view - 4-17-2015 at 10:29 AM

Keep in mind the earth curvature is equal to 8" per mile.

Bob53 - 4-17-2015 at 10:53 AM

Assuming nothing is obstructing the signal like mountains.

larryC - 4-17-2015 at 11:00 AM

I have done it. Years ago I ran a yacht for a guy and he wanted to boost the power of his VHF radio so he could make marine calls form farther off shore through the marine operator. He consulted a communications shop in San Diego and they recommended an amplifier for the (as I remember) mobile or truckers. The bandwidth it boosted covered the marine frequencies. Anyway we installed it and it seemed to work some but not worth the money. We were able to make calls from Cortez and Tanner banks with it and without it we couldn't make those calls. We didn't have a side band radio so we couldn't go through KMI.

rts551 - 4-17-2015 at 11:43 AM

boosted from what to watt? (haha). I use a Kenwood mobile radio in both the boat and chase vehicle...and it is plenty at 65 watts.

Gulliver - 4-17-2015 at 12:55 PM

The point we are making is that boosting your power might help you be heard further but will do nothing for your reception. Back when the whole VHF marine system was being designed, the test showed that the current limit of 25 watts was all that could be used to advantage.

So go ahead and run high power. You will irritate far more people (grin).

bledito - 4-17-2015 at 12:59 PM

take the batteries out and lick em and then reinstall em should give you a bit of a jolt

Hook - 4-17-2015 at 02:27 PM

Quote: Originally posted by rts551  
boosted from what to watt? (haha). I use a Kenwood mobile radio in both the boat and chase vehicle...and it is plenty at 65 watts.


Yes, but that's not a marine radio.

There are safety advantages to being heard from farther away, which is what the OP might be asking about. You'll get out to more radio operators with higher powered radios, especially land stations operating above the 25 watt legal limit (25w limit in the US). You might hear them and they might hear you, better.

I guess this assumes the OP is talking about installing a linear amp in a boat. It's possible he wants more out of his/her "base station".

Do a search. With the advent of Chinese electronics (heck, Chinese EVERYTHING!) linear amps have come down in price. Look for a VHF amplifier that covers the 2 meter band (close enough for the marine band). Certainly dont get one over 100 watts, as that's probably the max your antenna can handle. 50 watts is probably enough for most situations. I operate a VHF radio at 50 watts and can usually talk to stations 75 miles away on a regular basis and if atmospherics are favorable, I have talked to boats south of La Paz from San Carlos, Sonora. Generally, I can usually hail a base station at Juncalito, south of Loreto. She/he probably is operating above 25 watts, too.

As mentioned, antenna height is critical. My antenna is about 100 feet above sea level. But without the increased power, my signal wont get across to Chivato.

If one is hoping to do this using a 12v system, you'd better keep the conversations short or have the engine(s), genny running because putting out 50-100 watts is a significant power drain on a single 12v battery. It would be unfortunate to be shooting the chit on a small battery bank and not be able to fire up the engine after bragging about all the fish you are coming in with. :no:




[Edited on 4-17-2015 by Hook]

rts551 - 4-17-2015 at 03:03 PM

Hook. true but I programmed in all the Marine Frequencies...so You wouldn't know that it is not a "marine" radio.

[Edited on 4-18-2015 by rts551]

Gulliver - 4-17-2015 at 03:25 PM

Indeed, I too use my ham rig on the marine frequencies and it goes up to 50 watts. The days when only a certified radio was stable enough are long behind us. Modern H.F ham rigs do well on SSB frequencies as well. All of the rigs designed in the last 20 years that I have had on the bench have been more than accurate enough. The IC-735's were the only older rigs that could be on in receive and off frequency on transmit.

As for legalities, the U.S.C.G. and the F.C.C. have far higher priorities that fussing over vessels that are not required to be equipped. Especially in foreign waters.

As far as Mexico is concerned, there hasn't been an inspection of a ham or SSB rig on a foreign vessel, vehicle or residence in the 25 years I've been here.

The mildly irritating thing is that Mexico is party to a reciprocal licensing treaty with the U.S. wherein a Mexican ham doesn't need any permit to operate in the U.S. and according to the treaty neither does a U.S. ham need any such permit in Mexico. But they still take the ~$75 every six months if you want to go pay it.

As is usual, it's just for the small change. I talked to the head of the Mexican F.C.C. in 1992 at a LaPaz ham club meeting. I asked how I might get a copy of the Mexican operating regulations. He smiled at me and said, "Be a gentleman." Try that with our F.C.C.!

Hook - 4-18-2015 at 09:27 AM

Quote: Originally posted by rts551  
Hook. true but I programmed in all the Marine Frequencies...so You wouldn't know that it is not a "marine" radio.

[Edited on 4-18-2015 by rts551]


Yeah, I have one, too, but it's used as a base station. 90% of the ham/SSB radios aren't really protected enough from the elements, for use on a boat, unless you have a pretty enclosed radio location. Otherwise, I would have one on my Skipjack 25, too.

Thanks for the edit. I was wondering what the KOOK meant. Thought it was some 21st century techie acronym that I haven't heard.

rts551 - 4-18-2015 at 10:14 AM

Quote: Originally posted by Hook  
Quote: Originally posted by rts551  
Hook. true but I programmed in all the Marine Frequencies...so You wouldn't know that it is not a "marine" radio.

[Edited on 4-18-2015 by rts551]


Yeah, I have one, too, but it's used as a base station. 90% of the ham/SSB radios aren't really protected enough from the elements, for use on a boat, unless you have a pretty enclosed radio location. Otherwise, I would have one on my Skipjack 25, too.

Thanks for the edit. I was wondering what the KOOK meant. Thought it was some 21st century techie acronym that I haven't heard.


My mistake. Didn't catch it until later. it was an "ah sheet" moment.

VHF marine band

captkw - 4-18-2015 at 12:41 PM

Based on 156.00 mghz and up....height above the water does play a big roll in the picture...if you going up past 20 ft you need to switch from rg 58 to rg8 and install a bi amp for best results..also always over looked is the power supply !! a good regulated pwr supply is Soo important for TX..any add ons in the transmission line (insertion loss) is not a good way to go.. in radio..you get what you pay for !! there is a product called..................mmmm I think antenna wrap for the pl connecters and is worth its weight in gold for protecting the ant. pl connects in a marine area,, house and or boat....K&T

[Edited on 4-18-2015 by captkw]