antennas

[bob lico]

i think it would be a good idea to have a monthly post on a common subject that all 31 bertram owners encounter. i just purchase two 4018 shakespeare 19' antennas,one port one starboard with standoffs on the radar arch.one will be for the icom on the bridge the other for the backup raymarine in the salon.i wanted to put a 6 or 3db on the top of the radar arch with a dedicated splinter(the ones that will switch back and forth)if your talking to someone 100' away in rolling waves.would like to have inputs from the pros like bruce and also the guys like jp,vic roy,and brewster who use the vhf in all kinds of conditions offshore with years of hands on experiance.---c-mon guys tell us what you know it is a safety factor for the "brotherhood"

[JP Dalik]

Wow, I just signed in before bed and found a question I could answer. Here's my thoughts:
If your in close quarters drop down to 1watt and chat away. You have a better shot of over powering (being on 25w) a boat that's close to you as opposed to sending the signal over them.
I've never had a problem even in the big boats talkin to little boats and verse visa. If your really concerned about safety add a handheld to the arsenal.
Even with the 4018 @ 19ft your still only 25 ft off the water to the tips. Hell my families center console with 8 ft antennas is 13 ft to the tips.
Chat away the splices and splitters just add more connections and potential problem areas.
Good Luck.

[bob lico]

a very modest jp "a question i can answer" i consider jp the best of the best ,on the question why do the big boys have so many antennas ? i assumed they were using a 3db for close up and 9db for every thing else.you bring up a good point cut the wattage instead of switching ant.i just assumed the 9db in a rolling sea would be a detrimental for vhf conversation up close.i am sure spliter would have some effect on relieability due to loss of signal at connections but would be the only solution to the problem.i carry a hand held in the ditch bag but hope i don`t need it.

[Dave Kosh R.I.P.]

Bob ,
In my opinion it would be a little over kill to use another antenna except for a VHF emergency antenna. That is quite a common practice on commercial boats. They usually have one embedded into the glass on a bridge roof as the emergency back-up. If you get caught in very very rough seas like 12 footers you may loose your 19 foot antenna or it may be severely damged. Fact of life with wind load etc. So all in all the most practical way as I do it is just carry a hand held . They are pretty cheap, now days.
P.S .You made a wise choice in the big antenna . Big difference in performanace even at the same height as your old smaller antenna. The 3 db differnce is the same as increasing your power to 50 watts from a 6 db gain antenna. The receive portion is also enhanced by double the sensitivity effectively (means you'll hear boats further away from your old antenna). Just make sure you got a good bracket and have it powder coated like I did mine on the SSB antenna . Dave K

[Brewster Minton]

I have three antennas. One for my main radio, then the backup and then one that is not hooked up to anything that I could use after a lightning stike if I am alive. I have three handhelds also each attached to Mustang suits. For what Im doing, more is better. Oh, no splitters, you want it strait from radio to the antenna is the best. And JP is right about power.

[Mikey]

Good questions, good answers. But which antenna after all of that? Did I miss something?

[Brewster Minton]

I have two antennas made by Digital corp and one Shakeyspear. When the Shakyspear snaps I will replace it with a Digital 8' like the others. Ref pics bellow. I hope that helps Mikey.

[bob lico]

mike o what is your antennas set up.now that i read these posts i will use one 19'-9db for the bridge and a 8' on the top of the arch for the back up.i have 3 of those 8' digital antennas in the basement .no spliters and use the hand held for up close or like jp said step down the wattage for close up.

[In Memory Walter K]

Bob- The big 9db, the 8 ft 6dbs and the hand held covers all your bases. All of your vhf's have a low watt setting for boat to boat communications close up. My Icom vhf allows me to put a second plug-in handset with complete controls down below in the cockpit which I have found invaluable. Those calls when drifting, chumming, chunking etc., had me running up to the bridge all the time. No more. Walter

[In Memory of Vicroy]

Capt. Dave's observation about the effect of an increase in db gain is very important to understand how VHF radio waves work. Sure, it's line of sight most of the time, but the more db you got, the better it works. I use a 21' 9 db and get a lot of range out of my old Icom 125.

Now, with a good radio and good antenna, the system is only as good as the connector and the cable that ties the output of the radio to the antenna. RG 9 (the fat cable) is a lot better than the usual RG 58U (skinny cable). The PL 259 connector needs to have a real good solder job, and kept clean with CX on both the cable and radio ends. Another often overlooked VHF requirement is plenty of amps of 12VDC to the radio....if you see the backlight dim when you key the mike, check your breakers or fuses and consider increasing the wrie size that feeds the radio. Better yet, put a voltmeter on the radio 12VDC input and see what happens when you key the mike on high power. Most radios say they will work from about 10 to 18 VDC, but when the voltage drops below about 12 you are losing a lot of output power.

Sidebands, on the other hand, which operate at 150 watts, are a bear for power and I have a pair of #6s coming straight off the batteries thru a 30 amp fuse feeding it. Same with a 4KW+ radar, needs a lot of power to work right.

UV