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#1
posted to rec.boats.cruising
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VHF antenna anomaly
Well, I'm triangulating in on the problem. I made up a short jumper of 400
cable, and connected it to my kludge of a powered up setup for the nav radio dangling at the helm (instead of the arch antenna feed, with which we've already proven the radio good) and the antenna I took off the top of the mast. Loud and clear, just sitting in the cockpit holding the antenna outside the bimini - tip of the whip not higher than the boom - from a slightly distant point and a local as well, 5x5, even on low power. So, given the lousy positioning of the antenna (no height, no grounding), I conclude that the antenna is ok, of which I'm very gladdened, as dealing with one on the plane when I come back would be a nuisance. That leaves the cable, which I'm going to replace, rather than try to troubleshoot the several pieces of it (mast and at least two jumpers, perhaps as many as 4, I forget). Various discussions in various places have alternated between "it's so short, and the power is so small, that anything will do" to "nothing other than MilSpec, and, a bonus, it's lighter and thinner" and places in between. I'm all for lighter and thinner, and the best tx I can get, if the two are compatible, and forever-grade corrosion/sal****er/whatever protection I can get. So, what part number cable should I be looking for for best longevity, easiest handling and best throughput (is there a single item to do that?)? I know I may have to pay a couple (maybe more) bux a foot for it, but it's small potatoes in the boatbux equation, and I really don't want to do this again... Thanks, all. L8R Skip, glad I'm not having to deal with an antenna on the plane Morgan 461 #2 SV Flying Pig KI4MPC See our galleries at www.justpickone.org/skip/gallery ! Follow us at http://groups.yahoo.com/group/TheFlyingPigLog and/or http://groups.google.com/group/flyingpiglog "You are never given a wish without also being given the power to make it come true. You may have to work for it however." (and) "There is no such thing as a problem without a gift for you in its hand (Richard Bach) |
#2
posted to rec.boats.cruising
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VHF antenna anomaly
On Mon, 23 Nov 2009 18:30:46 -0500, "Flying Pig"
wrote: So, what part number cable should I be looking for for best longevity, easiest handling and best throughput (is there a single item to do that?)? I know I may have to pay a couple (maybe more) bux a foot for it, but it's small potatoes in the boatbux equation, and I really don't want to do this again... What I used with great success on my old Cal-34 was RG-142/U. Looking around on Google I just found a place that has it for $1.94/ft (non-MIL spec): http://www.wifi-parts.com/rg142u.html That is a good price in my opinion since some places are charging as much as $5/ft. Here's another source for the MIL spec version at $2.25/ft (over 50 ft): http://www.rfparts.com/coax.html#teflon Looks like they have the non-MIL spec version at $1.80, don't know what the difference is but my experience is with the MIL spec. It is easy to handle although no coax likes really sharp bends. |
#3
posted to rec.boats.cruising
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VHF antenna anomaly
Wayne.B wrote:
/snip/ http://www.rfparts.com/coax.html#teflon Looks like they have the non-MIL spec version at $1.80, don't know what the difference is but my experience is with the MIL spec. It is easy to handle although no coax likes really sharp bends. At a sharp left hand corner, a right hand loop beats a tight left bend, any day of the week. Brian W |
#4
posted to rec.boats.cruising
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VHF antenna anomaly
----- Original Message -----
From: "brian whatcott" Newsgroups: rec.boats.cruising Sent: Tuesday, November 24, 2009 7:24 AM Subject: VHF antenna anomaly Solid dielectric, double shield, preferably not pvc sheath which gives off acid decay products. Choose the correct characteristic impedance. Coax is offered in 50 to 70 ohm impedance. Above all: minimize I said MINIMIZE the number of BNC coax connections. They are lossy. You could consider low loss type connectors but it adds to the general confusion and cost I know. I hope you don't mean what I THINK you mean when you talk about jumpers. NO WIRE JUMPERS! Brian W Hi, Brian, Yes, when I said jumper I was referring to a short length to extend, or, in the particular post, just use as a very short feed line, to test the antenna (having previously proven the radio good). I have (in the end result) either 3 or 4 connectors, depending on how you look at it. First is at the radio. Second is at the connector which had to be bolted, so to speak, to the bracket, as the metz antenna threads don't go all the way through it. However, having said that, in my test which proved the antenna and the radio, I note that the metz has a very long male inside of it, a nylon bushing keeping the antenna feed short enough, against it, and then the connector piece which doesn't have threads all the way through it. If you look at my gallery, under SSI refit, then upgrades/electronics, you'll see the bulkhead connector I had to use to get the Metz stem long enough to connect, and the end result on the bracket at the top of the mast. Numbers 3 and/or 4 would be the double male adapter I had to mount to the top of that bulkhead connector to make the metz mount on it. HOWEVER, you've stimulated a thought which I presume would work: If I take that nylon bushing, stick it back in the Metz, and screw the body of the coil onto my bulkhead connector, that connector should replace the Metz stem reducing the connectors by either one or two. Thanks for stimulation; let me know, any of you, who find fault with that conclusion (replace the Metz stem with the bulkhead connector). So, if you conclude that the antenna itself should not be counted in connectors, I'd have two - one at the radio, and the other at the antenna. Am I correct? L8R Skip Morgan 461 #2 SV Flying Pig KI4MPC See our galleries at www.justpickone.org/skip/gallery ! Follow us at http://groups.yahoo.com/group/TheFlyingPigLog and/or http://groups.google.com/group/flyingpiglog "You are never given a wish without also being given the power to make it come true. You may have to work for it however." (and) "There is no such thing as a problem without a gift for you in its hand (Richard Bach) |
#5
posted to rec.boats.cruising
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VHF antenna anomaly
I followed the URL after "See our galleries..."
I looked for SSI refit, and didn't find it. I looked for upgrades/electronics and failed. So I admired the generally nice quality of the pix, and gave up. I can only suppose you were extending the center coax conductor at some connector with a wire, in order to stretch through a bulkhead. This is not good practice. Brian W Flying Pig wrote: ----- Original Message ----- From: "brian whatcott" Newsgroups: rec.boats.cruising Sent: Tuesday, November 24, 2009 7:24 AM Subject: VHF antenna anomaly Solid dielectric, double shield, preferably not pvc sheath which gives off acid decay products. Choose the correct characteristic impedance. Coax is offered in 50 to 70 ohm impedance. Above all: minimize I said MINIMIZE the number of BNC coax connections. They are lossy. You could consider low loss type connectors but it adds to the general confusion and cost I know. I hope you don't mean what I THINK you mean when you talk about jumpers. NO WIRE JUMPERS! Brian W Hi, Brian, Yes, when I said jumper I was referring to a short length to extend, or, in the particular post, just use as a very short feed line, to test the antenna (having previously proven the radio good). I have (in the end result) either 3 or 4 connectors, depending on how you look at it. First is at the radio. Second is at the connector which had to be bolted, so to speak, to the bracket, as the metz antenna threads don't go all the way through it. However, having said that, in my test which proved the antenna and the radio, I note that the metz has a very long male inside of it, a nylon bushing keeping the antenna feed short enough, against it, and then the connector piece which doesn't have threads all the way through it. If you look at my gallery, under SSI refit, then upgrades/electronics, you'll see the bulkhead connector I had to use to get the Metz stem long enough to connect, and the end result on the bracket at the top of the mast. Numbers 3 and/or 4 would be the double male adapter I had to mount to the top of that bulkhead connector to make the metz mount on it. HOWEVER, you've stimulated a thought which I presume would work: If I take that nylon bushing, stick it back in the Metz, and screw the body of the coil onto my bulkhead connector, that connector should replace the Metz stem reducing the connectors by either one or two. Thanks for stimulation; let me know, any of you, who find fault with that conclusion (replace the Metz stem with the bulkhead connector). So, if you conclude that the antenna itself should not be counted in connectors, I'd have two - one at the radio, and the other at the antenna. Am I correct? L8R Skip |
#6
posted to rec.boats.cruising
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Pix Question (WAS) VHF antenna anomaly
"brian whatcott" wrote in message
... I followed the URL after "See our galleries..." I looked for SSI refit, and didn't find it. I looked for upgrades/electronics and failed. So I admired the generally nice quality of the pix, and gave up. I can only suppose you were extending the center coax conductor at some connector with a wire, in order to stretch through a bulkhead. This is not good practice. Brian W Negative. Bulkhead mount, nuts on both sides of a longish connector. Try this... http://www.justpickone.org/skip/gall...es/Electronics Sorry about the confusion - I'd spoken so volubly here about all that happened in Saint Simons Island that I should have also specified 2009 refit vs early refit... L8R Skip -- Morgan 461 #2 SV Flying Pig KI4MPC See our galleries at www.justpickone.org/skip/gallery ! Follow us at http://groups.yahoo.com/group/TheFlyingPigLog and/or http://groups.google.com/group/flyingpiglog "You are never given a wish without also being given the power to make it come true. You may have to work for it however." (and) "There is no such thing as a problem without a gift for you in its hand (Richard Bach) Flying Pig wrote: |
#7
posted to rec.boats.cruising
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VHF antenna anomaly
Solid dielectric, double shield, preferably not pvc sheath which gives
off acid decay products. Choose the correct characteristic impedance. Coax is offered in 50 to 70 ohm impedance. Above all: minimize I said MINIMIZE the number of BNC coax connections. They are lossy. You could consider low loss type connectors but it adds to the general confusion and cost I know. I hope you don't mean what I THINK you mean when you talk about jumpers. NO WIRE JUMPERS! Brian W Flying Pig wrote: ... That leaves the cable, which I'm going to replace, rather than try to troubleshoot the several pieces of it (mast and at least two jumpers, perhaps as many as 4, I forget). Various discussions in various places have alternated between "it's so short, and the power is so small, that anything will do" to "nothing other than MilSpec, and, a bonus, it's lighter and thinner" and places in between. I'm all for lighter and thinner, and the best tx I can get, if the two are compatible, and forever-grade corrosion/sal****er/whatever protection I can get. So, what part number cable should I be looking for for best longevity, easiest handling and best throughput (is there a single item to do that?)? I know I may have to pay a couple (maybe more) bux a foot for it, but it's small potatoes in the boatbux equation, and I really don't want to do this again... Thanks, all. L8R Skip, glad I'm not having to deal with an antenna on the plane Morgan 461 #2 SV Flying Pig KI4MPC See our galleries at www.justpickone.org/skip/gallery ! Follow us at http://groups.yahoo.com/group/TheFlyingPigLog and/or http://groups.google.com/group/flyingpiglog "You are never given a wish without also being given the power to make it come true. You may have to work for it however." (and) "There is no such thing as a problem without a gift for you in its hand (Richard Bach) |
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