| Home |
| Search |
| Today's Posts |
|
#1
|
|||
|
|||
VHF Radio Range Problem
I suspect that my Marine VHF radio is a little lacking in range, even on the
25W setting. It's an older style Navico, I only get about a 10 mile range out at sea, Yacht to yacht, although I can just reach the Coast Guard from around the Eddystone (about 15 miles to the coast) This woulnd't seem so bad, except my brand new ICOM M31 portable gives exactly the same range, both tramistting and receiving, and that's using it down at deck level, and at only 5W output! whereas my Main boat VHF has an aerial on the top of the mast. Does anyone have any thoughts about what range I can expect yacht to yacht on a 32 footer sailing boat with mast head antenna with 25 Watts. I am considering purchasing the ICOM M421, do you think this is the best bet, or could the aerial be faulty. I have checked all the deck level connections and these seem OK. Tips and hints welcome. Cheers, John |
|
#2
|
|||
|
|||
|
I had the same problem on my Pearson 303. I was told that the antenta wire
going up the mast had chaffed through and was shorting out. I replaced the wire and now it works fine. It is the original radio from 1985 on the boat. "MazingTree" wrote in message .uk... I suspect that my Marine VHF radio is a little lacking in range, even on the 25W setting. It's an older style Navico, I only get about a 10 mile range out at sea, Yacht to yacht, although I can just reach the Coast Guard from around the Eddystone (about 15 miles to the coast) This woulnd't seem so bad, except my brand new ICOM M31 portable gives exactly the same range, both tramistting and receiving, and that's using it down at deck level, and at only 5W output! whereas my Main boat VHF has an aerial on the top of the mast. Does anyone have any thoughts about what range I can expect yacht to yacht on a 32 footer sailing boat with mast head antenna with 25 Watts. I am considering purchasing the ICOM M421, do you think this is the best bet, or could the aerial be faulty. I have checked all the deck level connections and these seem OK. Tips and hints welcome. Cheers, John |
|
#3
|
|||
|
|||
|
Ah that's encouraging. Another reply in UK.rec.sailing (didn't see the
electronics group!) concurs with this thought. I think I shall replace the antenna and aerial, unless I can get the Vtronix Antenna apart to replace just the cable. Sounds worth doing first anyway. John "Richard" wrote in message ... I had the same problem on my Pearson 303. I was told that the antenta wire going up the mast had chaffed through and was shorting out. I replaced the wire and now it works fine. It is the original radio from 1985 on the boat. "MazingTree" wrote in message .uk... I suspect that my Marine VHF radio is a little lacking in range, even on the 25W setting. It's an older style Navico, I only get about a 10 mile range out at sea, Yacht to yacht, although I can just reach the Coast Guard from around the Eddystone (about 15 miles to the coast) This woulnd't seem so bad, except my brand new ICOM M31 portable gives exactly the same range, both tramistting and receiving, and that's using it down at deck level, and at only 5W output! whereas my Main boat VHF has an aerial on the top of the mast. Does anyone have any thoughts about what range I can expect yacht to yacht on a 32 footer sailing boat with mast head antenna with 25 Watts. I am considering purchasing the ICOM M421, do you think this is the best bet, or could the aerial be faulty. I have checked all the deck level connections and these seem OK. Tips and hints welcome. Cheers, John |
|
#4
|
|||
|
|||
|
In article ,
"MazingTree" wrote: I suspect that my Marine VHF radio is a little lacking in range, even on the 25W setting. It's an older style Navico, I only get about a 10 mile range out at sea, Yacht to yacht, although I can just reach the Coast Guard from around the Eddystone (about 15 miles to the coast) This woulnd't seem so bad, except my brand new ICOM M31 portable gives exactly the same range, both tramistting and receiving, and that's using it down at deck level, and at only 5W output! whereas my Main boat VHF has an aerial on the top of the mast. Does anyone have any thoughts about what range I can expect yacht to yacht on a 32 footer sailing boat with mast head antenna with 25 Watts. I am considering purchasing the ICOM M421, do you think this is the best bet, or could the aerial be faulty. I have checked all the deck level connections and these seem OK. Tips and hints welcome. Cheers, John I would suspect the antenna and or coax cable in your case. Sounds like a simple case of old tired coax, or detuned, ort failing antenna. Here in the North Pacific, we usually are getting 50+ miles boat to boat with 25 Watts and 10db antennas on 0ver 300 ton Coastal Freighters, with some paths reaching out to 90+ miles. Of course your milage may vary, as to Actual Tx Power, and Receiver Sensitivity, and Antenna losses. Bruce in alaska -- add a 2 before @ |
|
#5
|
|||
|
|||
|
If your boat is fiberglass or wood, make certain you have a ground plane for
the antenna. The earth connection of your transceiver needs to connect to large matt or screen on the hull which is connected electrically with the water. Some boat builders bond the screen into the deck. As a check, borrow a VHF base station antenna and see if it performs correctly. If it does, you have found your problem. Now fixing it, is another matter. Steve "MazingTree" wrote in message .uk... I suspect that my Marine VHF radio is a little lacking in range, even on the 25W setting. It's an older style Navico, I only get about a 10 mile range out at sea, Yacht to yacht, although I can just reach the Coast Guard from around the Eddystone (about 15 miles to the coast) This woulnd't seem so bad, except my brand new ICOM M31 portable gives exactly the same range, both tramistting and receiving, and that's using it down at deck level, and at only 5W output! whereas my Main boat VHF has an aerial on the top of the mast. Does anyone have any thoughts about what range I can expect yacht to yacht on a 32 footer sailing boat with mast head antenna with 25 Watts. I am considering purchasing the ICOM M421, do you think this is the best bet, or could the aerial be faulty. I have checked all the deck level connections and these seem OK. Tips and hints welcome. Cheers, John |
|
#6
|
|||
|
|||
|
Used my VHF for a 1300 nm contact today.
krj Steve Lusardi wrote: If your boat is fiberglass or wood, make certain you have a ground plane for the antenna. The earth connection of your transceiver needs to connect to large matt or screen on the hull which is connected electrically with the water. Some boat builders bond the screen into the deck. As a check, borrow a VHF base station antenna and see if it performs correctly. If it does, you have found your problem. Now fixing it, is another matter. Steve "MazingTree" wrote in message .uk... I suspect that my Marine VHF radio is a little lacking in range, even on the 25W setting. It's an older style Navico, I only get about a 10 mile range out at sea, Yacht to yacht, although I can just reach the Coast Guard from around the Eddystone (about 15 miles to the coast) This woulnd't seem so bad, except my brand new ICOM M31 portable gives exactly the same range, both tramistting and receiving, and that's using it down at deck level, and at only 5W output! whereas my Main boat VHF has an aerial on the top of the mast. Does anyone have any thoughts about what range I can expect yacht to yacht on a 32 footer sailing boat with mast head antenna with 25 Watts. I am considering purchasing the ICOM M421, do you think this is the best bet, or could the aerial be faulty. I have checked all the deck level connections and these seem OK. Tips and hints welcome. Cheers, John |
|
#8
|
|||
|
|||
|
"MazingTree" wrote in
.uk: It's an older style Navico, I only get about a 10 mile range out at sea, Yacht to yacht, although I can just reach the Coast Guard from around the Eddystone (about 15 miles to the coast) This woulnd't seem so bad, except my brand new ICOM M31 portable gives exactly the same range, both tramistting and receiving, and that's using it down at deck level, and at only 5W output! whereas my Main boat VHF has an aerial on the top of the mast. Ok, let's splurge and drop by Waste Marine for a Shakespeare VHF power/SWR meter. It's a little white meter with a switch and adjustment control on the front and two coax connectors, one on each side. $30. You'll need a short coax jumper to go from the meter's transmitter connector to the VHF transceiver. If you also buy two right-angle PL-259/SO-239 connectors to make the coax jacks come out the back of it, instead of the side, you can make a neat permanent installation of the meter on the panel next to the radio so you KNOW it's actually transmitting and that the antenna is OK at any time you don't get an answer. Use is simple. To check the antenna out, put the meter switch in the SET position, key the transmitter on some channel in the middle of the band (NOT CHANNEL 16!) and rotate the little adjustment control until the meter is at the SET mark at full scale. Now, switch to SWR position and read the SWR scale on the meter, while still holding the transmitter keyed. A perfect antenna, which rarely exists, will show no movement of the needle off the 1 on the SWR scale, indicating no reflected power back from the antenna. All the power is going out on the air. Any reading on SWR below 2:1 (the 2 on the SWR scale) is fine. 2:1 means you're losing 10% of your power back from the antenna. At the antenna it's worse than that but noone can really tell the difference out on the horizon between 25W and 15W. If the SWR is higher than 2:1, especially if it goes way up off the SWR scale, which only goes halfway up at 3:1, the antenna or the cable is TOAST...probably from a lightning hit or broken coaxial cable. Worst case....SWR sucks over 3:1....what now?...... Now we get out the bosun's chair and have the galley slaves haul us, and our SWR meter, up the mast to the antenna. Move the jumper coax cable from the transmitter jack to the antenna jack as up at the top it will be jumpering the meter to the antenna. Unplug the coax cable off the antenna, after the galley slaves secure the line to a cleat, please, and connect it to the transmitter jack on our meter. Connect the open end of the jumper coax to the antenna. Move a galley slave to the radio and have him/her turn it on. Repeat the SWR set and measurement procedure above. If you have to significantly move the SET control from the position you had it at the transceiver end of the coax....or.....if you get little or no reading at all....the coax is TOAST. Replace it and start measuring again. Ok, what if we get good power level up the coax? Switch to SWR position and read the SWR under the antenna, now. It would normally be a little higher than what you'd measure at the transceiver on a good antenna because the reflected power that makes the SWR position run is attenuated by the cable when we measured it back at the radio. That'd be normal. Again, the SWR here should be less than 2:1. If it's high, the antenna is toast! Go to your favorite marine "discount" dealer and order a Metz Manta 6 VHF antenna, not that piece of plastic crap with COAX RUNNING OUT OF THE PLASTIC they'll invariably try to pawn off on your. The Metz is guaranteed for life. They'll send you a new one if you ever tear up this one. It's the best antenna for sailboat masts....damned near indestructable. it comes with a right-angle stainless bracket to mount it to the mast if your current one isn't compatible. http://www.metzcommunication.com/manta6.htm You won't need the handrail mount. Mounted on the handrail sucks. ALTITUDE IS OUR FRIEND ON VHF! Does anyone have any thoughts about what range I can expect yacht to yacht on a 32 footer sailing boat with mast head antenna with 25 Watts. Daytime, normal weather....50' mast to 50' mast...probably 15 miles...a little over the visual horizon from the top of the mast. VHF is line-of- sight to the radio horizon. Mathematically it's: http://continuouswave.com/whaler/reference/VHF.html As you can see from that, the major concern is "path loss" and antenna height. The 3dB Metz gives you double whatever power is at the end of the cable atop the mast in Effective Radiated Power (ERP) The 6dB antenna is too tall to make sense up there...easily destroyed plastic. I am considering purchasing the ICOM M421, do you think this is the best bet, or could the aerial be faulty. I have checked all the deck level connections and these seem OK. Before we spend hundreds on a new radio, let's get the antenna checked out with the cheap meter, first. If the SWR is reasonable, under 2:1, when you test it at the radio, THEN we'll flip the switch to POWER mode and read the handy little wattmeter, which is "fairly accurate" at LOW SWR READINGS, being most accurate at 1:1 with no reflected power. Check the 25W high power and 1 watt low power in this meter mode. As the SWR increases, this reading increases, so don't get way excited if it reads 30 watts at 2:1 SWR. It was calibrated into a perfect dummy load at the factory. Now, of course, if you're reading ZERO and can't get the meter to SET in SWR mode....then we've got a bad transmitter. Your choice to repair or replace. If it's old, dump it. They stopped making my beloved M-59 the jetboat jumping waves couldn't destroy...dammit. Lionheart has an M-602 on the mainmast Metz and an M-59 on the mizzen lower down. Captain Geoffrey likes the way the M-602 matches the M-802 HF panel...(c; There's no difference in the range of the big expensive 602 and the old M-59 I can tell. M-59 has new clothes. They call it the M-302, now. If you don't need the extra toys of the M-402, like remote Commander mic, etc., it has the same radio operation. Any Icom is fine. M-127s, the Radio Of The Year back in 2000 and before, is a great radio. They're still available, but discontinued, now. Gotta keep cranking up those model numbers, you know! As the range webpage shows, 10 miles is pretty fair, boat 2 boat on VHF. The investment in the little SWR/Power meter will help you find out the true health of the radio/antenna/cable combo....Everyone should buy one. |
|
#9
|
|||
|
|||
|
"Steve Lusardi" wrote in
: If your boat is fiberglass or wood, make certain you have a ground plane for the antenna. The earth connection of your transceiver needs to connect to large matt or screen on the hull which is connected electrically with the water. Some boat builders bond the screen into the deck. As a check, borrow a VHF base station antenna and see if it performs correctly. If it does, you have found your problem. Now fixing it, is another matter. Steve The end-fed halfwave antennas, such as the Metz Manta-6 do not require any ground or groundplane at all. The antenna rod, itself, is a total 1/2 wavelength dipole, but fed from the bottom end. No ground is necessary. http://www.metzcommunication.com/manta6.htm Guaranteed for life.... |
|
#10
|
|||
|
|||
|
The Antenna system is a Vtronix Great Hawk, the one with the Wind indicator
built into it. Since I first posted, I have spoken with their technical man, and he was very helpful, and explained that it's fitted with a special solderless connection to enable the cable to be unscrewed and checked. from my description to him, it sounds like the aerial has been up the mast for a long time though, so I may swap the antenna anyway, whilst I am up the mast. He says it is possible after a very extended period of time for the antenna to become faulty due corrosion and possibly water ingress. John wrote in message ... On 2005-06-06 said: I had the same problem on my Pearson 303. I was told that the antenna wire going up the mast had chaffed through and was shorting out. I replaced the wire and now it works fine. It is the original radio from 1985 on the boat. THat was my first thought. Check your feedline and the antenna, make sure the feedline is good and your antenna system not corroded or otherwise less than optimum. IF your antenna on the mast with 25 watts can't outperform your portable then you've got a problem somewhere. I note you didn't say waht kind of antenna you were using with the portable. However I'd do some real servicing to the antenna system before I rushed out and bought a new transceiver. Richard Webb, amateur radio callsign nf5b active on the Maritime Mobile service network, 14.300 mhz REplace anything before the @ symbol with elspider for real email -- agood captain is one who is hoisting his first drink in a bar when the storm hits. |
| Reply |
| Thread Tools | Search this Thread |
| Display Modes | |
|
|
Similar Threads
|
||||
| Thread | Forum | |||
| Modifying Icom IC-M800 | Electronics | |||
| USING GPS WITH VHF RADIO (DSC) HELP | General | |||
| RDF for newbies and NN of KN | ASA | |||
| Ext spkr for VHF Radio | Electronics | |||
| back with a problem now | General | |||
Linear Mode
