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Boat Forum / Cruising / July 2006VHF installation questions
I just bought a Quest GX 1255S, not because I plan to start yacking at vessels that don't give way (see other threads) but so I'll have something with more range than the handheld when I cruise downeast in a couple weeks. The instructions say to have the standing wave etc. checked out by a radio technician after installation. Is this just CYA by the manufacturer or is it a must do? I suspect it will cost nearly as much as the radio the way these things go and I've got a couple weeks to try and raise some distant boats to check the range. The coax running through my cabin and up the mast is pretty old but the antenna and loading coil(?) at the top are brand new. Would somebody please refresh my memory on the proper procedure for a radio check? I think I remember most of the other stuff. Is there a good on-line site describing marine radio procedures?  SignatureRoger Long > I just bought a Quest GX 1255S, not because I plan to start yacking at > vessels that don't give way (see other threads) but so I'll have [quoted text clipped - 14 lines] > > Is there a good on-line site describing marine radio procedures? Just don't do it on 16. Here on the west coast the Coast Guard will do one for you on 22a. Gary >> I just bought a Quest GX 1255S, not because I plan to start yacking at >> vessels that don't give way (see other threads) but so I'll have [quoted text clipped - 19 lines] > > Gary A radio check on 22a? First of all, calling the CG for a radio check won't tell you much, since they can receive very poor signals. Second, 22a is reserved for when the CG needs more information from a boater when it's not an emergency. Typically, any other channel besides 16 is allowed. I believe they prefer 9. >>>I just bought a Quest GX 1255S, not because I plan to start yacking at >>>vessels that don't give way (see other threads) but so I'll have [quoted text clipped - 25 lines] > an emergency. Typically, any other channel besides 16 is allowed. I believe > they prefer 9. Like I said, here the Coast Guard tell you to call on 22a. It may be different where you are. The advantage of a Coast Guard radio check is the can check your signal on a variety of repeaters and tell you how far you are going. They can even DF you! Receiving poor signals may be neccessary if your radio isn't working properly, and they'll tell you that too. >>>>I just bought a Quest GX 1255S, not because I plan to start yacking at >>>>vessels that don't give way (see other threads) but so I'll have [quoted text clipped - 32 lines] > neccessary if your radio isn't working properly, and they'll tell you that > too. Here? I sail in the SF area. They don't like being hailed for radio checks, and you can't hail on 22a. Signature"j" ganz @@ www.sailnow.com >Here? I sail in the SF area. They don't like being hailed for radio checks, >and you can't hail on 22a. A popular radio check strategy around here is to call SeaTow on channel 16, switch to a working channel, and ask for a signal report. They seem to be OK with it, and it is a legit use of 16. I usually wait for someone else to ask for a radio check then respond, checking mine in the process. On a good day, this usually doesn't take more than 30 minutes. >>Here? I sail in the SF area. They don't like being hailed for radio >>checks, [quoted text clipped - 4 lines] > > They seem to be OK with it, and it is a legit use of 16. I agree... calling SeaTow is a reasonable thing to do. If nothing else, free advertising for them. :-) Signature"j" ganz @@ www.sailnow.com > Like I said, here the Coast Guard tell you to call on 22a. It may be > different where you are. The advantage of a Coast Guard radio check is > the can check your signal on a variety of repeaters and tell you how far > you are going. They can even DF you! Receiving poor signals may be > neccessary if your radio isn't working properly, and they'll tell you > that too. Bzzzt, Wrong Information..... Maybe the Canadian Coast Guard can do what you say, but the USCG is about 10 years behind in DCS and Vhf DF Deployment, and do NOT have that capability on most of the US Coastline. Yes, they do have a good VHF HighSite Deployment but these are not DCS or DF Capable, for the most part, and will not be for a few more years. The congress wants the USCG to be watching for Terrorists not answering Distress Calls from Idiot Yatchmen. This Quest GX 1255S is a very decent VHF with selective digital calling. Once your radio is installed you should call your local coast guard on the proper channel for voice testing. In my area we use 12 and 14 other area use 22A. To get the best out of this radio you should replace your coaxial cable and connectors. I prefer the RG8 cable and the solder type connectors. If you have never installed connectors with soldering get someone that knows how to do it because it is no fun to go up and down the mast to re - do a connections. As for testing the Digital Selective Calling you have to connect your VHF to your GPS. Then you have to register your VHF with the Coast Guard. They in turn will enter the information of your boat and VHF in their data banks. After you can test your VHF with them. When they receive your call a little window will appear on their digital radar showing your position, name of your boat and any safety equipment you may have listed. As a safety precaution you should check for any Electro Magnetic Interference with transmitting. You compass course should read correctly and your autopilot should steer accordingly. The older produced autopilots were not as well shielded as the new one and sometime when transmitting the autopilot compass behaved erratically. >> I just bought a Quest GX 1255S, not because I plan to start yacking at >> vessels that don't give way (see other threads) but so I'll have [quoted text clipped - 19 lines] > > Gary >I just bought a Quest GX 1255S, not because I plan to start yacking at >vessels that don't give way (see other threads) but so I'll have [quoted text clipped - 6 lines] >much as the radio the way these things go and I've got a couple weeks >to try and raise some distant boats to check the range. an SWR meter is not that expensive. Once you have it, you could quickly recoup the entire purchase price by performing SWR checks for others at $5-$10 a pop. CWM >an SWR meter is not that expensive. Once you have it, you could quickly recoup >the entire purchase price by performing SWR checks for others at $5-$10 a pop. $39.95 http://www.walcottcb.com/valor-v6050-vhf-marine-swr-power-watt-meter-p-920.html Looks like a great business model to me. Signature"j" ganz @@ www.sailnow.com >>an SWR meter is not that expensive. Once you have it, you could quickly >>recoup [quoted text clipped - 4 lines] > > http://www.walcottcb.com/valor-v6050-vhf-marine-swr-power-watt-meter-p-920.html > I just bought a Quest GX 1255S, not because I plan to start yacking at > vessels that don't give way (see other threads) but so I'll have [quoted text clipped - 14 lines] > > Is there a good on-line site describing marine radio procedures? A couple of suggestions, Roger. First, if you want to check your swr, you can do it yourself quite simply with an swr meter (WM sell them, as do Radio Shack). Just make sure it is intended for VHF use. These meters can also be used to measure power. If you're not putting power into the coax/antenna, the meter will tell you. But if the coax is lossy, the meter will probably think all is grand and report normal power output so beware of false positives. Normally, swr is not a problem, but if your coax is old, it may be lossy or pinched, or punctured. You can simply compare your hand-held to the Quest on a somewhat distant station. Make sure the squelch is turned down so you hear the hiss. Your Quest ought to produce a much louder signal. Having done a listening test, you can then move to an on-the-air transmitter test as described by the other posters. You can even compare your hand-held to the Quest on transmit if you can find a willing partner. If either the listening test or the transmitting test is unsatisfactory, then there's a chance the coax is causing problems and you may need to replace it. It can be tested in place with a time domain reflectometry scope, but your tech is not likely to have one handy. Good luck. Chuck Roger's post said he's "looking for more range" than a handheld can provide; the only way to feel good about an 'installed' VHF (assume mast mounted antenna) system is to know that the antenna is 'accepting' all of the power delivered to it (as opposed to 'rejecting', or 'reflecting' some of it back to the transmitter - a rough definition of 'Standing Waves'). If you know any Ham (Amateur Radio) operators, ask if you can borrow their "Bird Model 43" thruline wattmeter. Easy to use, and the results will provide peace of mind about your new radios ability to provide "more range." Note: Because receivers are so sensitive these days, even a very poorly matched antenna will likely result in a "sounds ok to me skipper" radio check. This seems to me to be a poor way to check a vital piece of safety equipment... MW Los Angeles I just called a marine electronics shop and they said to "just do a radio check". Couldn't tell me if there was a preferred channel in this area such as is reported for the West Coast (22 A). Maybe if I'd bought the radio from them:) SignatureRoger Long > Roger's post said he's "looking for more range" than a handheld can > provide; the only way to feel good about an 'installed' VHF (assume [quoted text clipped - 17 lines] > MW > Los Angeles >I just called a marine electronics shop and they said to "just do a >radio check". Couldn't tell me if there was a preferred channel in >this area such as is reported for the West Coast (22 A). > >Maybe if I'd bought the radio from them:) Make a call to a specific vessel or shore station (marina, yacht club, SEATOW, etc.), on either ch 16 or 9. Otherwise you can buy your own SWR bridge for about $40. > Roger's post said he's "looking for more range" than a handheld can > provide; the only way to feel good about an 'installed' VHF (assume > mast mounted antenna) system is to know that the antenna is 'accepting' > all of the power delivered to it (as opposed to 'rejecting', or > 'reflecting' some of it back to the transmitter - a rough definition of > 'Standing Waves'). Mike, as I pointed out in an earlier post, an SWR meter may not reliably indicate the condition of the transmission line, which is acknowledged to be old. If the line is new and conforms to spec, the SWR meter at the transmitter will give a fairly reliable SWR reading. It will understate actual SWR the greater the line losses (which increase with length) and the higher the frequency. And the older the line on a boat, the greater the losses. The meter will read SWR correctly, but the SWR will not tell how much power goes to the antenna and how much is lost in the line. So with an old line, a low SWR reading is not too informative, no matter how accurate the meter. If the SWR reads high, there may be a problem. If it reads low, other testing may be appropriate. There are other simple tests that can be done with a DMM, but it is usually best if the antenna is disconnected for them. I don't think Roger is too interested in measurements, though, and there is a lot of wisdom in the notion that if you want to know if your big VHF is louder than your handheld VHF, the best way to find out is to see if it IS louder. ;-) The real advantage of the big VHF is not its power, but its antenna and the antenna's height. One could not easily distinguish between a handheld 5 watt VHF and a 25 watt VHF if both are connected to the same antenna. Chuck If you know any Ham (Amateur Radio) operators, ask > if you can borrow their "Bird Model 43" thruline wattmeter. Easy to > use, and the results will provide peace of mind about your new radios [quoted text clipped - 5 lines] > MW > Los Angeles >> Roger's post said he's "looking for more range" than a handheld can >> provide; the only way to feel good about an 'installed' VHF (assume [quoted text clipped - 48 lines] > >Chuck Many SWR meters also include a field strength test. CWM Sorry Chuck, but with frequency modulation (used with marine VHF radios), the 'loudness' of a received signal has *nothing to do* with the transmitter's power output or quality of the antenna system. Asking "can you hear me now?" of a fellow mariner in the same harbor seems a dubious way of checking the integrity of a vital communications system. The most likely failure mechanism for an 'old' coax is water migration into the cable - which generally happens at the antenna connection. This *will* change the impedance of the cable, which *will* show up on the thruline, or VSWR meter. "Old coax" in and of itself usually doesn't "become lossy" simply becuase of it's age; 100 year old copper conducts just as freely as 'new' copper. MW I don't think Roger is too interested in measurements, though, and there is a lot of wisdom in the notion that if you want to know if your big VHF is louder than your handheld VHF, the best way to find out is to see if it IS louder. ;-) > Sorry Chuck, but with frequency modulation (used with marine VHF > radios), the 'loudness' of a received signal has *nothing to do* with > the transmitter's power output or quality of the antenna system. Asking > "can you hear me now?" of a fellow mariner in the same harbor seems a > dubious way of checking the integrity of a vital communications system. Disagree, Mike. My recommendation was that the squelch be turned down so that hiss could be heard. FM carriers of different strengths will differ in the amount of quieting they produce. It's pretty intuitive. Even with the squelch on, weaker signals may not break the squelch. You're probably thinking of the limiter function in an FM receiver which irons out changes in amplitude from the modulation. But that's not involved in the weak signal test I suggested. But I sure agree that "can you hear me now?" won't do it. Remember the objective as you yourself correctly stated it: looking for more range than the handheld (or,is the Quest louder than the handheld). With the squelch down and a distant station cooperating, I see no reason a simple and positive comparison of the two radios can't be made. Regarding coax, usually there is no deterioration of the copper itself, although braids are sometimes eaten away in a marine environment. What happens is that the dielectric changes as it becomes contaminated. Measure the capacitance of a piece of coax that's been in a boat for ten years. Additional shunt capacitance will attenuate signals. Measure the leakage resistance between the center conductor and the braid and compare that to a new cable. Many sailboats have coax connectors in or near the bilge at the base of the mast to facilitate dismasting, and these connectors tend to be contaminated after many years. Chuck > Sorry Chuck, but with frequency modulation (used with marine VHF > radios), the 'loudness' of a received signal has *nothing to do* with [quoted text clipped - 14 lines] > your big VHF is louder than your handheld VHF, the best way to find out > is to see if it IS louder. ;-) I agree with MW, even pick a few marinas at nearby ports and see how far away you can hail them from! It just sounds like from a time standpoint, you could get a simple answer this way the fastest. Assuming all works acceptable, after the cruise, break out the meters and get technical. A lot of these users have great ideas for you. |
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