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VHF cable type?
I have to replace the wiring in my 58' mast plus 20' to my radio; my
question is this. RG 8x vs RG 8U. I know I lose more power with the 8x but what does than translate to in watts output at the antenna. The West Marine Advisor doesn't address this in a laymans POV. I need the reduced size. Thanks Bruce -- Bruce and Elaine www.cruisinglife.net |
VHF cable type?
"Bruce" writes: I have to replace the wiring in my 58' mast plus 20' to my radio; my question is this. RG 8x vs RG 8U. snip RG8U and support it with a messenger cable. The difference in cost gets lost in the wash. I use 1/16" S/S cable and secure the RG8U to it with tie wraps every 2'-3'. If you don't support it, it will stretch and the impedance will change or so I was told by a radio guru I trust. HTH -- Lew S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland) Visit: http://home.earthlink.net/~lewhodgett for Pictures |
VHF cable type?
"Bruce" writes: I have to replace the wiring in my 58' mast plus 20' to my radio; my question is this. RG 8x vs RG 8U. snip RG8U and support it with a messenger cable. The difference in cost gets lost in the wash. I use 1/16" S/S cable and secure the RG8U to it with tie wraps every 2'-3'. If you don't support it, it will stretch and the impedance will change or so I was told by a radio guru I trust. HTH -- Lew S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland) Visit: http://home.earthlink.net/~lewhodgett for Pictures |
VHF cable type?
I took a look at some sample specs to get a feel for the losses.
RG8X 7-9 dB/100 ft @ 400MHz RG8U 4 dB/100 ft @ 400 MHz You likely won't be operating at 400 MHz, but I'll use these figures all the same. (Lower Fx is less lossy) And I'll suppose that, what with the connectors, the loss is 8dB versus 4 dB That's 4 more dB 8 dB means you lose about 84% of your transmitter power. 4 dB means you lose about 60% of your power So do you want 40 or do you want 16 ?? Brian Whatcott Altus OK On Sat, 17 Jan 2004 00:46:44 GMT, "Lew Hodgett" wrote: "Bruce" writes: I have to replace the wiring in my 58' mast plus 20' to my radio; my question is this. RG 8x vs RG 8U. snip RG8U and support it with a messenger cable. The difference in cost gets lost in the wash. I use 1/16" S/S cable and secure the RG8U to it with tie wraps every 2'-3'. If you don't support it, it will stretch and the impedance will change or so I was told by a radio guru I trust. HTH |
VHF cable type?
I took a look at some sample specs to get a feel for the losses.
RG8X 7-9 dB/100 ft @ 400MHz RG8U 4 dB/100 ft @ 400 MHz You likely won't be operating at 400 MHz, but I'll use these figures all the same. (Lower Fx is less lossy) And I'll suppose that, what with the connectors, the loss is 8dB versus 4 dB That's 4 more dB 8 dB means you lose about 84% of your transmitter power. 4 dB means you lose about 60% of your power So do you want 40 or do you want 16 ?? Brian Whatcott Altus OK On Sat, 17 Jan 2004 00:46:44 GMT, "Lew Hodgett" wrote: "Bruce" writes: I have to replace the wiring in my 58' mast plus 20' to my radio; my question is this. RG 8x vs RG 8U. snip RG8U and support it with a messenger cable. The difference in cost gets lost in the wash. I use 1/16" S/S cable and secure the RG8U to it with tie wraps every 2'-3'. If you don't support it, it will stretch and the impedance will change or so I was told by a radio guru I trust. HTH |
VHF cable type?
Lionheart's 55' mainmast has a Shakespeare 1/2 wave VHF antenna on top
with about 75' of RG-58A/U military surplus cable to an Icom M-602 VHF radio. Her smaller mizzenmast has another Shakespeare 1/2 wave VHF on top with about 50' of the same mil-spec RG-58A/U. I can talk to the Savannah, GA, USCG station about 100 miles away on a weekday when the kiddies aren't jamming the channel from the mainmast antenna on 25W from Ashley Marina's crowded docks behind the James Island Connector bridge blocking my path. If I had to start from scratch, and couldn't buy a 500' roll of surplus RG-58A/U for $10 at my local thrift shop, I'd opt for a foil-shielded 8X size, not copper braided shield which is awful lossy. The drawback here is most of them have solid center conductors and foam dielectrics which makes ANY sharp turns winding it up into the mast, for instance, out of the question because solid conductors will MIGRATE through the foam, ruining their characteristics you pay extra for and possibly shorting which is worse..... Aboard Lionheart, it was all moot as we had to pull the cable through several fairly sharp bends just to get it from the stepped mast into the cabin and in some tight places from there to the radios. For this reason, alone, I recommend using VERY flexible, and reliable, Polyethelene-cored, finely stranded center conductor RG-58A/U (not RG-58/U which has a solid center conductor) for your purpose. All those fancy loss charts mean nothing when the fancy foam cables are pulled through a sharp turn, somewhere. Hell, you can wind RG-58A/U in a hangman's noose and it'll still work great! REALITY CHECK!! On Fri, 16 Jan 2004 19:13:20 -0500, "Bruce" wrote: I have to replace the wiring in my 58' mast plus 20' to my radio; my question is this. RG 8x vs RG 8U. I know I lose more power with the 8x but what does than translate to in watts output at the antenna. The West Marine Advisor doesn't address this in a laymans POV. I need the reduced size. Thanks Bruce -- Bruce and Elaine www.cruisinglife.net Larry W4CSC |
VHF cable type?
Lionheart's 55' mainmast has a Shakespeare 1/2 wave VHF antenna on top
with about 75' of RG-58A/U military surplus cable to an Icom M-602 VHF radio. Her smaller mizzenmast has another Shakespeare 1/2 wave VHF on top with about 50' of the same mil-spec RG-58A/U. I can talk to the Savannah, GA, USCG station about 100 miles away on a weekday when the kiddies aren't jamming the channel from the mainmast antenna on 25W from Ashley Marina's crowded docks behind the James Island Connector bridge blocking my path. If I had to start from scratch, and couldn't buy a 500' roll of surplus RG-58A/U for $10 at my local thrift shop, I'd opt for a foil-shielded 8X size, not copper braided shield which is awful lossy. The drawback here is most of them have solid center conductors and foam dielectrics which makes ANY sharp turns winding it up into the mast, for instance, out of the question because solid conductors will MIGRATE through the foam, ruining their characteristics you pay extra for and possibly shorting which is worse..... Aboard Lionheart, it was all moot as we had to pull the cable through several fairly sharp bends just to get it from the stepped mast into the cabin and in some tight places from there to the radios. For this reason, alone, I recommend using VERY flexible, and reliable, Polyethelene-cored, finely stranded center conductor RG-58A/U (not RG-58/U which has a solid center conductor) for your purpose. All those fancy loss charts mean nothing when the fancy foam cables are pulled through a sharp turn, somewhere. Hell, you can wind RG-58A/U in a hangman's noose and it'll still work great! REALITY CHECK!! On Fri, 16 Jan 2004 19:13:20 -0500, "Bruce" wrote: I have to replace the wiring in my 58' mast plus 20' to my radio; my question is this. RG 8x vs RG 8U. I know I lose more power with the 8x but what does than translate to in watts output at the antenna. The West Marine Advisor doesn't address this in a laymans POV. I need the reduced size. Thanks Bruce -- Bruce and Elaine www.cruisinglife.net Larry W4CSC |
VHF cable type?
All these numbers mean NOTHING if you pull foam cable around a CORNER.
The solid center conductor migrates through the flimsy foam that gives it such a great set of numbers and it goes all to hell...... Solid center conductors also BREAK if you bend them back and forth as the loose cable in the mast moves back and forth and back and forth on every wave. RG-58A/U has the same loss AFTER you pull it than when it was on the reel. It's very flexible, finely stranded center conductor and very hard polyethelene dielectric will take a helluva beating with no migration around tight turns. Most boats I know have no room for inch and a half hardline from the radio to the mast......dammit. 58A/U (not 58/U which is solid centered) works great for years and years......It's made for MOBILE service. On Sat, 17 Jan 2004 03:42:59 GMT, Brian Whatcott wrote: I took a look at some sample specs to get a feel for the losses. RG8X 7-9 dB/100 ft @ 400MHz RG8U 4 dB/100 ft @ 400 MHz You likely won't be operating at 400 MHz, but I'll use these figures all the same. (Lower Fx is less lossy) And I'll suppose that, what with the connectors, the loss is 8dB versus 4 dB That's 4 more dB 8 dB means you lose about 84% of your transmitter power. 4 dB means you lose about 60% of your power So do you want 40 or do you want 16 ?? Brian Whatcott Altus OK On Sat, 17 Jan 2004 00:46:44 GMT, "Lew Hodgett" wrote: "Bruce" writes: I have to replace the wiring in my 58' mast plus 20' to my radio; my question is this. RG 8x vs RG 8U. snip RG8U and support it with a messenger cable. The difference in cost gets lost in the wash. I use 1/16" S/S cable and secure the RG8U to it with tie wraps every 2'-3'. If you don't support it, it will stretch and the impedance will change or so I was told by a radio guru I trust. HTH Larry W4CSC |
VHF cable type?
All these numbers mean NOTHING if you pull foam cable around a CORNER.
The solid center conductor migrates through the flimsy foam that gives it such a great set of numbers and it goes all to hell...... Solid center conductors also BREAK if you bend them back and forth as the loose cable in the mast moves back and forth and back and forth on every wave. RG-58A/U has the same loss AFTER you pull it than when it was on the reel. It's very flexible, finely stranded center conductor and very hard polyethelene dielectric will take a helluva beating with no migration around tight turns. Most boats I know have no room for inch and a half hardline from the radio to the mast......dammit. 58A/U (not 58/U which is solid centered) works great for years and years......It's made for MOBILE service. On Sat, 17 Jan 2004 03:42:59 GMT, Brian Whatcott wrote: I took a look at some sample specs to get a feel for the losses. RG8X 7-9 dB/100 ft @ 400MHz RG8U 4 dB/100 ft @ 400 MHz You likely won't be operating at 400 MHz, but I'll use these figures all the same. (Lower Fx is less lossy) And I'll suppose that, what with the connectors, the loss is 8dB versus 4 dB That's 4 more dB 8 dB means you lose about 84% of your transmitter power. 4 dB means you lose about 60% of your power So do you want 40 or do you want 16 ?? Brian Whatcott Altus OK On Sat, 17 Jan 2004 00:46:44 GMT, "Lew Hodgett" wrote: "Bruce" writes: I have to replace the wiring in my 58' mast plus 20' to my radio; my question is this. RG 8x vs RG 8U. snip RG8U and support it with a messenger cable. The difference in cost gets lost in the wash. I use 1/16" S/S cable and secure the RG8U to it with tie wraps every 2'-3'. If you don't support it, it will stretch and the impedance will change or so I was told by a radio guru I trust. HTH Larry W4CSC |
VHF cable type?
Hi Larry W4CSC, I think you need to take a look at the cable suppliers' specs before telling us all about RG-58A/U 's wonderful features. Maybe take your blood pressure medicine too? Now about RG58A/U - this was the stuff you picked up for $10 at the surplus store, wasn't it? :-) this spec is available new in either foam OR solid insulation would you believe? I checked several suppliers before writing this note: perhaps you could check *your* facts too! You could start he http://www.radialllarsen.com/docfiles/Cables.pdf Brian Whatcott Altus OK On Sat, 17 Jan 2004 06:01:33 GMT, (Larry W4CSC) wrote: All these numbers mean NOTHING if you pull foam cable around a CORNER. The solid center conductor migrates through the flimsy foam that gives it such a great set of numbers and it goes all to hell...... Solid center conductors also BREAK if you bend them back and forth as the loose cable in the mast moves back and forth and back and forth on every wave. RG-58A/U has the same loss AFTER you pull it than when it was on the reel. It's very flexible, finely stranded center conductor and very hard polyethelene dielectric will take a helluva beating with no migration around tight turns. Most boats I know have no room for inch and a half hardline from the radio to the mast......dammit. 58A/U (not 58/U which is solid centered) works great for years and years......It's made for MOBILE service. On Sat, 17 Jan 2004 03:42:59 GMT, Brian Whatcott wrote: I took a look at some sample specs to get a feel for the losses. RG8X 7-9 dB/100 ft @ 400MHz RG8U 4 dB/100 ft @ 400 MHz You likely won't be operating at 400 MHz, but I'll use these figures all the same. (Lower Fx is less lossy) And I'll suppose that, what with the connectors, the loss is 8dB versus 4 dB That's 4 more dB 8 dB means you lose about 84% of your transmitter power. 4 dB means you lose about 60% of your power So do you want 40 or do you want 16 ?? Brian Whatcott Altus OK On Sat, 17 Jan 2004 00:46:44 GMT, "Lew Hodgett" wrote: "Bruce" writes: I have to replace the wiring in my 58' mast plus 20' to my radio; my question is this. RG 8x vs RG 8U. snip RG8U and support it with a messenger cable. The difference in cost gets lost in the wash. I use 1/16" S/S cable and secure the RG8U to it with tie wraps every 2'-3'. If you don't support it, it will stretch and the impedance will change or so I was told by a radio guru I trust. HTH Larry W4CSC |
VHF cable type?
I recommend checking with suppliers' specifications for cable
construction materials: solid or stranded? solid or foam insulation? %coverage of shield? Tape wrap? Non-acid outer sheath? before blindly implementing Larry's recommendation below on choosing cables. Yes: let's call it a reality check. Brian W On Sat, 17 Jan 2004 05:54:58 GMT, (Larry W4CSC) wrote: ... 55' mainmast has a Shakespeare 1/2 wave VHF antenna on top with about 75' of RG-58A/U military surplus cable/// If I had to start from scratch, and couldn't buy a 500' roll of surplus RG-58A/U for $10 at my local thrift shop... I recommend using VERY flexible, and reliable, Polyethelene-cored, finely stranded center conductor RG-58A/U (not RG-58/U which has a solid center conductor) for your purpose. All those fancy loss charts mean nothing when the fancy foam cables are pulled through a sharp turn, somewhere. Hell, you can wind RG-58A/U in a hangman's noose and it'll still work great! REALITY CHECK!! |
VHF cable type?
I recommend checking with suppliers' specifications for cable
construction materials: solid or stranded? solid or foam insulation? %coverage of shield? Tape wrap? Non-acid outer sheath? before blindly implementing Larry's recommendation below on choosing cables. Yes: let's call it a reality check. Brian W On Sat, 17 Jan 2004 05:54:58 GMT, (Larry W4CSC) wrote: ... 55' mainmast has a Shakespeare 1/2 wave VHF antenna on top with about 75' of RG-58A/U military surplus cable/// If I had to start from scratch, and couldn't buy a 500' roll of surplus RG-58A/U for $10 at my local thrift shop... I recommend using VERY flexible, and reliable, Polyethelene-cored, finely stranded center conductor RG-58A/U (not RG-58/U which has a solid center conductor) for your purpose. All those fancy loss charts mean nothing when the fancy foam cables are pulled through a sharp turn, somewhere. Hell, you can wind RG-58A/U in a hangman's noose and it'll still work great! REALITY CHECK!! |
VHF cable type?
I am looking at the Ancor brand RG-8x which has tined stranded core. Could
I also use this type wire for the 10' run from my SSB tuner to the backstay? What I had on the SSB was GTO-15??? Thanks Bruce "Brian Whatcott" wrote in message ... I recommend checking with suppliers' specifications for cable construction materials: solid or stranded? solid or foam insulation? %coverage of shield? Tape wrap? Non-acid outer sheath? before blindly implementing Larry's recommendation below on choosing cables. Yes: let's call it a reality check. Brian W On Sat, 17 Jan 2004 05:54:58 GMT, (Larry W4CSC) wrote: ... 55' mainmast has a Shakespeare 1/2 wave VHF antenna on top with about 75' of RG-58A/U military surplus cable/// If I had to start from scratch, and couldn't buy a 500' roll of surplus RG-58A/U for $10 at my local thrift shop... I recommend using VERY flexible, and reliable, Polyethelene-cored, finely stranded center conductor RG-58A/U (not RG-58/U which has a solid center conductor) for your purpose. All those fancy loss charts mean nothing when the fancy foam cables are pulled through a sharp turn, somewhere. Hell, you can wind RG-58A/U in a hangman's noose and it'll still work great! REALITY CHECK!! |
VHF cable type?
I am looking at the Ancor brand RG-8x which has tined stranded core. Could
I also use this type wire for the 10' run from my SSB tuner to the backstay? What I had on the SSB was GTO-15??? Thanks Bruce "Brian Whatcott" wrote in message ... I recommend checking with suppliers' specifications for cable construction materials: solid or stranded? solid or foam insulation? %coverage of shield? Tape wrap? Non-acid outer sheath? before blindly implementing Larry's recommendation below on choosing cables. Yes: let's call it a reality check. Brian W On Sat, 17 Jan 2004 05:54:58 GMT, (Larry W4CSC) wrote: ... 55' mainmast has a Shakespeare 1/2 wave VHF antenna on top with about 75' of RG-58A/U military surplus cable/// If I had to start from scratch, and couldn't buy a 500' roll of surplus RG-58A/U for $10 at my local thrift shop... I recommend using VERY flexible, and reliable, Polyethelene-cored, finely stranded center conductor RG-58A/U (not RG-58/U which has a solid center conductor) for your purpose. All those fancy loss charts mean nothing when the fancy foam cables are pulled through a sharp turn, somewhere. Hell, you can wind RG-58A/U in a hangman's noose and it'll still work great! REALITY CHECK!! |
VHF cable type?
This is the same Larry that says that he has a 150 watt VHF amplifier
to switch in the antenna line if he can't be heard. Yet he recommends using lossy rg58 cable. Old surplus stuff at that! When cable ages it does not always do so gracefully. The dielectric breaks down and the losses can be considerably higher than new cable. For the amount of work involved and the minimal cost of 100 feet of RG8 type cable, use the best NEW cable. RG8 with polyethylene insulation is the way to go unless you have a size restraint. And forget the aluminum wrap shield stuff. You are asking for trouble in the marine environment with aluminum. You do not need "high shielding" for a VHF radio. Foam insulation is not a good idea on a boat though. The center does migrate at bends. It is also very difficult to install connectors on foam cable. The heat from the soldering iron melts the insulation quickly and lets the center wire move to the side. Sometimes even shorting it. Regards Gary On Sat, 17 Jan 2004 18:53:08 GMT, Brian Whatcott wrote: I recommend checking with suppliers' specifications for cable construction materials: solid or stranded? solid or foam insulation? %coverage of shield? Tape wrap? Non-acid outer sheath? before blindly implementing Larry's recommendation below on choosing cables. Yes: let's call it a reality check. Brian W On Sat, 17 Jan 2004 05:54:58 GMT, (Larry W4CSC) wrote: ... 55' mainmast has a Shakespeare 1/2 wave VHF antenna on top with about 75' of RG-58A/U military surplus cable/// If I had to start from scratch, and couldn't buy a 500' roll of surplus RG-58A/U for $10 at my local thrift shop... I recommend using VERY flexible, and reliable, Polyethelene-cored, finely stranded center conductor RG-58A/U (not RG-58/U which has a solid center conductor) for your purpose. All those fancy loss charts mean nothing when the fancy foam cables are pulled through a sharp turn, somewhere. Hell, you can wind RG-58A/U in a hangman's noose and it'll still work great! REALITY CHECK!! |
VHF cable type?
This is the same Larry that says that he has a 150 watt VHF amplifier
to switch in the antenna line if he can't be heard. Yet he recommends using lossy rg58 cable. Old surplus stuff at that! When cable ages it does not always do so gracefully. The dielectric breaks down and the losses can be considerably higher than new cable. For the amount of work involved and the minimal cost of 100 feet of RG8 type cable, use the best NEW cable. RG8 with polyethylene insulation is the way to go unless you have a size restraint. And forget the aluminum wrap shield stuff. You are asking for trouble in the marine environment with aluminum. You do not need "high shielding" for a VHF radio. Foam insulation is not a good idea on a boat though. The center does migrate at bends. It is also very difficult to install connectors on foam cable. The heat from the soldering iron melts the insulation quickly and lets the center wire move to the side. Sometimes even shorting it. Regards Gary On Sat, 17 Jan 2004 18:53:08 GMT, Brian Whatcott wrote: I recommend checking with suppliers' specifications for cable construction materials: solid or stranded? solid or foam insulation? %coverage of shield? Tape wrap? Non-acid outer sheath? before blindly implementing Larry's recommendation below on choosing cables. Yes: let's call it a reality check. Brian W On Sat, 17 Jan 2004 05:54:58 GMT, (Larry W4CSC) wrote: ... 55' mainmast has a Shakespeare 1/2 wave VHF antenna on top with about 75' of RG-58A/U military surplus cable/// If I had to start from scratch, and couldn't buy a 500' roll of surplus RG-58A/U for $10 at my local thrift shop... I recommend using VERY flexible, and reliable, Polyethelene-cored, finely stranded center conductor RG-58A/U (not RG-58/U which has a solid center conductor) for your purpose. All those fancy loss charts mean nothing when the fancy foam cables are pulled through a sharp turn, somewhere. Hell, you can wind RG-58A/U in a hangman's noose and it'll still work great! REALITY CHECK!! |
VHF cable type?
GTO-15 is a single conductor (often 14 gage stranded) rubber
insulated pvc clad unshielded cable used for neon signs and ignition wires. It is chosen for its 15 kVolt insulation, which can handle most any 3 - 30 Mhz transmitter signals, which may involve high voltages, but it is unshielded. If the RG-8X you have in mind has stranded conductor and foam insulation, this will have a much lower working voltage (they seem to rate between 300 volts and 1500 volts). The people who get hot under the collar about foam insulation have a point; you can easily wipe out transmitter range by treading on that stuff just once. It is inevitably more delicate than solid insulation. In a marine environment, it is reasonable to go for durability where total runs are reasonably short. It's true that a hundred feet of cable up a tall mast can give away a lot of transmitter power at VHF and UHF; much more so at higher frequencies still, and you might want to consider a well secured and protected lower loss cable type there. In general, if the cable type you have been using has been satisfactory, that's the first option at renewal time. Above all, you don't pick a regular co ax for GPS antennas, where the losses mount rapidly. Hope this helps somewhat, without making too many people mad. I do have the FCC license to fool with these radio/radar installations commercially, for what its worth. Brian W On Sat, 17 Jan 2004 17:06:09 -0500, "Bruce" wrote: I am looking at the Ancor brand RG-8x which has tined stranded core. Could I also use this type wire for the 10' run from my SSB tuner to the backstay? What I had on the SSB was GTO-15??? Thanks Bruce "Brian Whatcott" wrote in message .. . I recommend checking with suppliers' specifications for cable construction materials: solid or stranded? solid or foam insulation? %coverage of shield? Tape wrap? Non-acid outer sheath? before blindly implementing Larry's recommendation below on choosing cables. Yes: let's call it a reality check. Brian W On Sat, 17 Jan 2004 05:54:58 GMT, (Larry W4CSC) wrote: ... 55' mainmast has a Shakespeare 1/2 wave VHF antenna on top with about 75' of RG-58A/U military surplus cable/// If I had to start from scratch, and couldn't buy a 500' roll of surplus RG-58A/U for $10 at my local thrift shop... I recommend using VERY flexible, and reliable, Polyethelene-cored, finely stranded center conductor RG-58A/U (not RG-58/U which has a solid center conductor) for your purpose. All those fancy loss charts mean nothing when the fancy foam cables are pulled through a sharp turn, somewhere. Hell, you can wind RG-58A/U in a hangman's noose and it'll still work great! REALITY CHECK!! |
VHF cable type?
GTO-15 is a single conductor (often 14 gage stranded) rubber
insulated pvc clad unshielded cable used for neon signs and ignition wires. It is chosen for its 15 kVolt insulation, which can handle most any 3 - 30 Mhz transmitter signals, which may involve high voltages, but it is unshielded. If the RG-8X you have in mind has stranded conductor and foam insulation, this will have a much lower working voltage (they seem to rate between 300 volts and 1500 volts). The people who get hot under the collar about foam insulation have a point; you can easily wipe out transmitter range by treading on that stuff just once. It is inevitably more delicate than solid insulation. In a marine environment, it is reasonable to go for durability where total runs are reasonably short. It's true that a hundred feet of cable up a tall mast can give away a lot of transmitter power at VHF and UHF; much more so at higher frequencies still, and you might want to consider a well secured and protected lower loss cable type there. In general, if the cable type you have been using has been satisfactory, that's the first option at renewal time. Above all, you don't pick a regular co ax for GPS antennas, where the losses mount rapidly. Hope this helps somewhat, without making too many people mad. I do have the FCC license to fool with these radio/radar installations commercially, for what its worth. Brian W On Sat, 17 Jan 2004 17:06:09 -0500, "Bruce" wrote: I am looking at the Ancor brand RG-8x which has tined stranded core. Could I also use this type wire for the 10' run from my SSB tuner to the backstay? What I had on the SSB was GTO-15??? Thanks Bruce "Brian Whatcott" wrote in message .. . I recommend checking with suppliers' specifications for cable construction materials: solid or stranded? solid or foam insulation? %coverage of shield? Tape wrap? Non-acid outer sheath? before blindly implementing Larry's recommendation below on choosing cables. Yes: let's call it a reality check. Brian W On Sat, 17 Jan 2004 05:54:58 GMT, (Larry W4CSC) wrote: ... 55' mainmast has a Shakespeare 1/2 wave VHF antenna on top with about 75' of RG-58A/U military surplus cable/// If I had to start from scratch, and couldn't buy a 500' roll of surplus RG-58A/U for $10 at my local thrift shop... I recommend using VERY flexible, and reliable, Polyethelene-cored, finely stranded center conductor RG-58A/U (not RG-58/U which has a solid center conductor) for your purpose. All those fancy loss charts mean nothing when the fancy foam cables are pulled through a sharp turn, somewhere. Hell, you can wind RG-58A/U in a hangman's noose and it'll still work great! REALITY CHECK!! |
VHF cable type?
Brian
The RG 8x has stranded core and a solid insulator. What you are saying is it will be good but not perfect. If I have a 25 watt VHF transmitter, I should expect ??? wattsoutput at the end of an 80' wire. I am trying to decide if I should go through the aggrivation of the thicker wire or accept a loss in power. I need to find a 10' piece of the GTO-15 for my Icom 700pro. Thanks Bruce "Brian Whatcott" wrote in message ... GTO-15 is a single conductor (often 14 gage stranded) rubber insulated pvc clad unshielded cable used for neon signs and ignition wires. It is chosen for its 15 kVolt insulation, which can handle most any 3 - 30 Mhz transmitter signals, which may involve high voltages, but it is unshielded. If the RG-8X you have in mind has stranded conductor and foam insulation, this will have a much lower working voltage (they seem to rate between 300 volts and 1500 volts). The people who get hot under the collar about foam insulation have a point; you can easily wipe out transmitter range by treading on that stuff just once. It is inevitably more delicate than solid insulation. In a marine environment, it is reasonable to go for durability where total runs are reasonably short. It's true that a hundred feet of cable up a tall mast can give away a lot of transmitter power at VHF and UHF; much more so at higher frequencies still, and you might want to consider a well secured and protected lower loss cable type there. In general, if the cable type you have been using has been satisfactory, that's the first option at renewal time. Above all, you don't pick a regular co ax for GPS antennas, where the losses mount rapidly. Hope this helps somewhat, without making too many people mad. I do have the FCC license to fool with these radio/radar installations commercially, for what its worth. Brian W On Sat, 17 Jan 2004 17:06:09 -0500, "Bruce" wrote: I am looking at the Ancor brand RG-8x which has tined stranded core. Could I also use this type wire for the 10' run from my SSB tuner to the backstay? What I had on the SSB was GTO-15??? Thanks Bruce "Brian Whatcott" wrote in message .. . I recommend checking with suppliers' specifications for cable construction materials: solid or stranded? solid or foam insulation? %coverage of shield? Tape wrap? Non-acid outer sheath? before blindly implementing Larry's recommendation below on choosing cables. Yes: let's call it a reality check. Brian W On Sat, 17 Jan 2004 05:54:58 GMT, (Larry W4CSC) wrote: ... 55' mainmast has a Shakespeare 1/2 wave VHF antenna on top with about 75' of RG-58A/U military surplus cable/// If I had to start from scratch, and couldn't buy a 500' roll of surplus RG-58A/U for $10 at my local thrift shop... I recommend using VERY flexible, and reliable, Polyethelene-cored, finely stranded center conductor RG-58A/U (not RG-58/U which has a solid center conductor) for your purpose. All those fancy loss charts mean nothing when the fancy foam cables are pulled through a sharp turn, somewhere. Hell, you can wind RG-58A/U in a hangman's noose and it'll still work great! REALITY CHECK!! |
VHF cable type?
Brian
The RG 8x has stranded core and a solid insulator. What you are saying is it will be good but not perfect. If I have a 25 watt VHF transmitter, I should expect ??? wattsoutput at the end of an 80' wire. I am trying to decide if I should go through the aggrivation of the thicker wire or accept a loss in power. I need to find a 10' piece of the GTO-15 for my Icom 700pro. Thanks Bruce "Brian Whatcott" wrote in message ... GTO-15 is a single conductor (often 14 gage stranded) rubber insulated pvc clad unshielded cable used for neon signs and ignition wires. It is chosen for its 15 kVolt insulation, which can handle most any 3 - 30 Mhz transmitter signals, which may involve high voltages, but it is unshielded. If the RG-8X you have in mind has stranded conductor and foam insulation, this will have a much lower working voltage (they seem to rate between 300 volts and 1500 volts). The people who get hot under the collar about foam insulation have a point; you can easily wipe out transmitter range by treading on that stuff just once. It is inevitably more delicate than solid insulation. In a marine environment, it is reasonable to go for durability where total runs are reasonably short. It's true that a hundred feet of cable up a tall mast can give away a lot of transmitter power at VHF and UHF; much more so at higher frequencies still, and you might want to consider a well secured and protected lower loss cable type there. In general, if the cable type you have been using has been satisfactory, that's the first option at renewal time. Above all, you don't pick a regular co ax for GPS antennas, where the losses mount rapidly. Hope this helps somewhat, without making too many people mad. I do have the FCC license to fool with these radio/radar installations commercially, for what its worth. Brian W On Sat, 17 Jan 2004 17:06:09 -0500, "Bruce" wrote: I am looking at the Ancor brand RG-8x which has tined stranded core. Could I also use this type wire for the 10' run from my SSB tuner to the backstay? What I had on the SSB was GTO-15??? Thanks Bruce "Brian Whatcott" wrote in message .. . I recommend checking with suppliers' specifications for cable construction materials: solid or stranded? solid or foam insulation? %coverage of shield? Tape wrap? Non-acid outer sheath? before blindly implementing Larry's recommendation below on choosing cables. Yes: let's call it a reality check. Brian W On Sat, 17 Jan 2004 05:54:58 GMT, (Larry W4CSC) wrote: ... 55' mainmast has a Shakespeare 1/2 wave VHF antenna on top with about 75' of RG-58A/U military surplus cable/// If I had to start from scratch, and couldn't buy a 500' roll of surplus RG-58A/U for $10 at my local thrift shop... I recommend using VERY flexible, and reliable, Polyethelene-cored, finely stranded center conductor RG-58A/U (not RG-58/U which has a solid center conductor) for your purpose. All those fancy loss charts mean nothing when the fancy foam cables are pulled through a sharp turn, somewhere. Hell, you can wind RG-58A/U in a hangman's noose and it'll still work great! REALITY CHECK!! |
VHF cable type?
Noone is forcing anyone to use it. It works well for us in poly
dielectric and stranded centers. It bends around corners without damage, which in our application was key. Bend foam 8X or 8 hard around a corner every boat has will destroy it. That makes the cable spec sheet all BS...... Larry W4CSC |
VHF cable type?
Noone is forcing anyone to use it. It works well for us in poly
dielectric and stranded centers. It bends around corners without damage, which in our application was key. Bend foam 8X or 8 hard around a corner every boat has will destroy it. That makes the cable spec sheet all BS...... Larry W4CSC |
VHF cable type?
Bruce,
this is a lift of Budgetmarine's site which carries notes in pdf form: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~ Coaxial Cable Coax cable transfers your radio transmitter's energy to the antenna. It is precisely made, with the impedance matched to VHF-radios. Bigger cable diameter results in less signal loss.We carry three kinds of coaxial cable that are suitable for your VHF: RG-58, RG-8U, and RG-8X. Use the RG-58 for short runs only, the RG-8X for runs up to 60' (18m) and the low loss RG-8U for longer runs. Note that splicing co-ax cable can result in dramatic losses - by a factor of 10 if done poorly or with improper connectors. Coax Size vs Signal Loss Cable Diameter Loss / 100’ Length for 3dB loss RG-58 0.195" 6.1dB 49’ RG-8X 0.245" 4.5dB 66’ RG-8U 0.410" 2.7dB 111’ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ` That strikes a fairly common sense note. But remember, cable characteristics of the same nominal type vary, and some are more delicate than others, and more susceptible to UV, and damp...... ....but to answer your question: 25 watts into 80 ft of RG-8X (using the specs given above which apply at VHF) implies 50% loss at 66 ft, and there's another 10% over the remaining 14 ft --so about 10 watts get into the antenna. (Could you hoist the whole radio up the stick? It would boost output power to more than double if you just ran audio and power up 80 ft! - Jest kidding...) Their RG8U numbers give an 80 ft loss of about 36% leaving 16 watts available for the antenna. Here's the thing: You probably could not notice the difference between 16 watts and 10 watts emitted. So I suggest you avoid the aggravation of going with the thicker stuff. Brian W On Sat, 17 Jan 2004 20:21:41 -0500, "McCampbell" wrote: Brian The RG 8x has stranded core and a solid insulator. What you are saying is it will be good but not perfect. If I have a 25 watt VHF transmitter, I should expect ??? wattsoutput at the end of an 80' wire. I am trying to decide if I should go through the aggrivation of the thicker wire or accept a loss in power. I need to find a 10' piece of the GTO-15 for my Icom 700pro. Thanks Bruce "Brian Whatcott" wrote in message .. . GTO-15 is a single conductor (often 14 gage stranded) rubber insulated pvc clad unshielded cable used for neon signs and ignition wires. It is chosen for its 15 kVolt insulation, which can handle most any 3 - 30 Mhz transmitter signals, which may involve high voltages, but it is unshielded. If the RG-8X you have in mind has stranded conductor and foam insulation, this will have a much lower working voltage (they seem to rate between 300 volts and 1500 volts). The people who get hot under the collar about foam insulation have a point; you can easily wipe out transmitter range by treading on that stuff just once. It is inevitably more delicate than solid insulation. In a marine environment, it is reasonable to go for durability where total runs are reasonably short. It's true that a hundred feet of cable up a tall mast can give away a lot of transmitter power at VHF and UHF; much more so at higher frequencies still, and you might want to consider a well secured and protected lower loss cable type there. In general, if the cable type you have been using has been satisfactory, that's the first option at renewal time. Above all, you don't pick a regular co ax for GPS antennas, where the losses mount rapidly. Hope this helps somewhat, without making too many people mad. I do have the FCC license to fool with these radio/radar installations commercially, for what its worth. Brian W On Sat, 17 Jan 2004 17:06:09 -0500, "Bruce" wrote: I am looking at the Ancor brand RG-8x which has tined stranded core. Could I also use this type wire for the 10' run from my SSB tuner to the backstay? What I had on the SSB was GTO-15??? Thanks Bruce |
VHF cable type?
Bruce,
this is a lift of Budgetmarine's site which carries notes in pdf form: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~ Coaxial Cable Coax cable transfers your radio transmitter's energy to the antenna. It is precisely made, with the impedance matched to VHF-radios. Bigger cable diameter results in less signal loss.We carry three kinds of coaxial cable that are suitable for your VHF: RG-58, RG-8U, and RG-8X. Use the RG-58 for short runs only, the RG-8X for runs up to 60' (18m) and the low loss RG-8U for longer runs. Note that splicing co-ax cable can result in dramatic losses - by a factor of 10 if done poorly or with improper connectors. Coax Size vs Signal Loss Cable Diameter Loss / 100’ Length for 3dB loss RG-58 0.195" 6.1dB 49’ RG-8X 0.245" 4.5dB 66’ RG-8U 0.410" 2.7dB 111’ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ` That strikes a fairly common sense note. But remember, cable characteristics of the same nominal type vary, and some are more delicate than others, and more susceptible to UV, and damp...... ....but to answer your question: 25 watts into 80 ft of RG-8X (using the specs given above which apply at VHF) implies 50% loss at 66 ft, and there's another 10% over the remaining 14 ft --so about 10 watts get into the antenna. (Could you hoist the whole radio up the stick? It would boost output power to more than double if you just ran audio and power up 80 ft! - Jest kidding...) Their RG8U numbers give an 80 ft loss of about 36% leaving 16 watts available for the antenna. Here's the thing: You probably could not notice the difference between 16 watts and 10 watts emitted. So I suggest you avoid the aggravation of going with the thicker stuff. Brian W On Sat, 17 Jan 2004 20:21:41 -0500, "McCampbell" wrote: Brian The RG 8x has stranded core and a solid insulator. What you are saying is it will be good but not perfect. If I have a 25 watt VHF transmitter, I should expect ??? wattsoutput at the end of an 80' wire. I am trying to decide if I should go through the aggrivation of the thicker wire or accept a loss in power. I need to find a 10' piece of the GTO-15 for my Icom 700pro. Thanks Bruce "Brian Whatcott" wrote in message .. . GTO-15 is a single conductor (often 14 gage stranded) rubber insulated pvc clad unshielded cable used for neon signs and ignition wires. It is chosen for its 15 kVolt insulation, which can handle most any 3 - 30 Mhz transmitter signals, which may involve high voltages, but it is unshielded. If the RG-8X you have in mind has stranded conductor and foam insulation, this will have a much lower working voltage (they seem to rate between 300 volts and 1500 volts). The people who get hot under the collar about foam insulation have a point; you can easily wipe out transmitter range by treading on that stuff just once. It is inevitably more delicate than solid insulation. In a marine environment, it is reasonable to go for durability where total runs are reasonably short. It's true that a hundred feet of cable up a tall mast can give away a lot of transmitter power at VHF and UHF; much more so at higher frequencies still, and you might want to consider a well secured and protected lower loss cable type there. In general, if the cable type you have been using has been satisfactory, that's the first option at renewal time. Above all, you don't pick a regular co ax for GPS antennas, where the losses mount rapidly. Hope this helps somewhat, without making too many people mad. I do have the FCC license to fool with these radio/radar installations commercially, for what its worth. Brian W On Sat, 17 Jan 2004 17:06:09 -0500, "Bruce" wrote: I am looking at the Ancor brand RG-8x which has tined stranded core. Could I also use this type wire for the 10' run from my SSB tuner to the backstay? What I had on the SSB was GTO-15??? Thanks Bruce |
VHF cable type?
Brian and Gary...good stuff. Now understanding the loss of power, it
would make sense to get an amp (Idon't think it would be legal) or have a second line run to the spreader on the mizzen.That would drop the run down to 30' and a corresponding increase in power. Thanks for you help Bruce "Gary Schafer" wrote in message ... This is the same Larry that says that he has a 150 watt VHF amplifier to switch in the antenna line if he can't be heard. Yet he recommends using lossy rg58 cable. Old surplus stuff at that! When cable ages it does not always do so gracefully. The dielectric breaks down and the losses can be considerably higher than new cable. For the amount of work involved and the minimal cost of 100 feet of RG8 type cable, use the best NEW cable. RG8 with polyethylene insulation is the way to go unless you have a size restraint. And forget the aluminum wrap shield stuff. You are asking for trouble in the marine environment with aluminum. You do not need "high shielding" for a VHF radio. Foam insulation is not a good idea on a boat though. The center does migrate at bends. It is also very difficult to install connectors on foam cable. The heat from the soldering iron melts the insulation quickly and lets the center wire move to the side. Sometimes even shorting it. Regards Gary On Sat, 17 Jan 2004 18:53:08 GMT, Brian Whatcott wrote: I recommend checking with suppliers' specifications for cable construction materials: solid or stranded? solid or foam insulation? %coverage of shield? Tape wrap? Non-acid outer sheath? before blindly implementing Larry's recommendation below on choosing cables. Yes: let's call it a reality check. Brian W On Sat, 17 Jan 2004 05:54:58 GMT, (Larry W4CSC) wrote: ... 55' mainmast has a Shakespeare 1/2 wave VHF antenna on top with about 75' of RG-58A/U military surplus cable/// If I had to start from scratch, and couldn't buy a 500' roll of surplus RG-58A/U for $10 at my local thrift shop... I recommend using VERY flexible, and reliable, Polyethelene-cored, finely stranded center conductor RG-58A/U (not RG-58/U which has a solid center conductor) for your purpose. All those fancy loss charts mean nothing when the fancy foam cables are pulled through a sharp turn, somewhere. Hell, you can wind RG-58A/U in a hangman's noose and it'll still work great! REALITY CHECK!! |
VHF cable type?
Brian and Gary...good stuff. Now understanding the loss of power, it
would make sense to get an amp (Idon't think it would be legal) or have a second line run to the spreader on the mizzen.That would drop the run down to 30' and a corresponding increase in power. Thanks for you help Bruce "Gary Schafer" wrote in message ... This is the same Larry that says that he has a 150 watt VHF amplifier to switch in the antenna line if he can't be heard. Yet he recommends using lossy rg58 cable. Old surplus stuff at that! When cable ages it does not always do so gracefully. The dielectric breaks down and the losses can be considerably higher than new cable. For the amount of work involved and the minimal cost of 100 feet of RG8 type cable, use the best NEW cable. RG8 with polyethylene insulation is the way to go unless you have a size restraint. And forget the aluminum wrap shield stuff. You are asking for trouble in the marine environment with aluminum. You do not need "high shielding" for a VHF radio. Foam insulation is not a good idea on a boat though. The center does migrate at bends. It is also very difficult to install connectors on foam cable. The heat from the soldering iron melts the insulation quickly and lets the center wire move to the side. Sometimes even shorting it. Regards Gary On Sat, 17 Jan 2004 18:53:08 GMT, Brian Whatcott wrote: I recommend checking with suppliers' specifications for cable construction materials: solid or stranded? solid or foam insulation? %coverage of shield? Tape wrap? Non-acid outer sheath? before blindly implementing Larry's recommendation below on choosing cables. Yes: let's call it a reality check. Brian W On Sat, 17 Jan 2004 05:54:58 GMT, (Larry W4CSC) wrote: ... 55' mainmast has a Shakespeare 1/2 wave VHF antenna on top with about 75' of RG-58A/U military surplus cable/// If I had to start from scratch, and couldn't buy a 500' roll of surplus RG-58A/U for $10 at my local thrift shop... I recommend using VERY flexible, and reliable, Polyethelene-cored, finely stranded center conductor RG-58A/U (not RG-58/U which has a solid center conductor) for your purpose. All those fancy loss charts mean nothing when the fancy foam cables are pulled through a sharp turn, somewhere. Hell, you can wind RG-58A/U in a hangman's noose and it'll still work great! REALITY CHECK!! |
VHF cable type?
On Sun, 18 Jan 2004 04:30:59 GMT, Brian Whatcott
wrote: Coax Size vs Signal Loss Cable Diameter Loss / 100’ Length for 3dB loss RG-58 0.195" 6.1dB 49’ RG-8X 0.245" 4.5dB 66’ RG-8U 0.410" 2.7dB 111’ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~` Is now an ok time to point out that 3db of signal on any receiver S-meter is about the width of the needle? The 1.6 dB loss between 8X and 58A is almost impossible to see on any S-meter you'll ever see. It's why we boost power in 10-20 dB increments on ham radio. You are hard pressed to see any difference between 25W - 4.5 dB and 25W - 6.1dB actually on the air. Larry W4CSC |
VHF cable type?
On Sun, 18 Jan 2004 04:30:59 GMT, Brian Whatcott
wrote: Coax Size vs Signal Loss Cable Diameter Loss / 100’ Length for 3dB loss RG-58 0.195" 6.1dB 49’ RG-8X 0.245" 4.5dB 66’ RG-8U 0.410" 2.7dB 111’ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~` Is now an ok time to point out that 3db of signal on any receiver S-meter is about the width of the needle? The 1.6 dB loss between 8X and 58A is almost impossible to see on any S-meter you'll ever see. It's why we boost power in 10-20 dB increments on ham radio. You are hard pressed to see any difference between 25W - 4.5 dB and 25W - 6.1dB actually on the air. Larry W4CSC |
VHF cable type?
On Sun, 18 Jan 2004 06:15:40 -0500, "Bruce"
wrote: Brian and Gary...good stuff. Now understanding the loss of power, it would make sense to get an amp (Idon't think it would be legal) or have a second line run to the spreader on the mizzen.That would drop the run down to 30' and a corresponding increase in power. Thanks for you help Bruce The amp IS illegal under normal use. However, most don't realize that in an emergency situation where life is endangered, all radio laws are null and void and any power is fine if it saves lives. Larry W4CSC |
VHF cable type?
On Sun, 18 Jan 2004 06:15:40 -0500, "Bruce"
wrote: Brian and Gary...good stuff. Now understanding the loss of power, it would make sense to get an amp (Idon't think it would be legal) or have a second line run to the spreader on the mizzen.That would drop the run down to 30' and a corresponding increase in power. Thanks for you help Bruce The amp IS illegal under normal use. However, most don't realize that in an emergency situation where life is endangered, all radio laws are null and void and any power is fine if it saves lives. Larry W4CSC |
VHF cable type?
As has been pointed out, the cable loss (within reason), is a somewhat moot point.
Given an antenna height of X, it is not hard to calculate the maximum expected range, plus some for refraction, then also given the typical receiver sensitivity, (assume 10 microvolts for a not-so-good receiver), and antenna gain, you'll find that the power required at the antenna is not much. When the boat's rock and roll effect on the antenna pattern is considered, the power requirements of course must go up. As a side note: low gain antennas are better in this respect, assuming the low gain is due to an wider vertical beam-width, and not just poor design. But in my estimation, the real key to reliable marine VHFcommunications is in the connectors. When a young lad I spent 5 years maintaining antennas (all frequencies) in a coastal environment, (actually, within 200 yards of the beach) and can assure you that an unprotected/exposed connector in salt air can bring an antenna to its knees in 3 to 6 months. Norm |
VHF cable type?
As has been pointed out, the cable loss (within reason), is a somewhat moot point.
Given an antenna height of X, it is not hard to calculate the maximum expected range, plus some for refraction, then also given the typical receiver sensitivity, (assume 10 microvolts for a not-so-good receiver), and antenna gain, you'll find that the power required at the antenna is not much. When the boat's rock and roll effect on the antenna pattern is considered, the power requirements of course must go up. As a side note: low gain antennas are better in this respect, assuming the low gain is due to an wider vertical beam-width, and not just poor design. But in my estimation, the real key to reliable marine VHFcommunications is in the connectors. When a young lad I spent 5 years maintaining antennas (all frequencies) in a coastal environment, (actually, within 200 yards of the beach) and can assure you that an unprotected/exposed connector in salt air can bring an antenna to its knees in 3 to 6 months. Norm |
VHF cable type?
In article ,
"Bruce" wrote: I am looking at the Ancor brand RG-8x which has tined stranded core. Could I also use this type wire for the 10' run from my SSB tuner to the backstay? What I had on the SSB was GTO-15??? Thanks Bruce "Brian Whatcott" wrote in message ... I recommend checking with suppliers' specifications for cable construction materials: solid or stranded? solid or foam insulation? %coverage of shield? Tape wrap? Non-acid outer sheath? before blindly implementing Larry's recommendation below on choosing cables. Yes: let's call it a reality check. Brian W On Sat, 17 Jan 2004 05:54:58 GMT, (Larry W4CSC) wrote: ... 55' mainmast has a Shakespeare 1/2 wave VHF antenna on top with about 75' of RG-58A/U military surplus cable/// If I had to start from scratch, and couldn't buy a 500' roll of surplus RG-58A/U for $10 at my local thrift shop... I recommend using VERY flexible, and reliable, Polyethelene-cored, finely stranded center conductor RG-58A/U (not RG-58/U which has a solid center conductor) for your purpose. All those fancy loss charts mean nothing when the fancy foam cables are pulled through a sharp turn, somewhere. Hell, you can wind RG-58A/U in a hangman's noose and it'll still work great! REALITY CHECK!! You could but it wouldn't have the insulation capabilities of the GTO-15 that was there in the first place. the installer used GTO-15 for a reason, can you figure out why? When you do you will have answered your own question. Bruce in alaska -- add a 2 before @ |
VHF cable type?
In article ,
"Bruce" wrote: I am looking at the Ancor brand RG-8x which has tined stranded core. Could I also use this type wire for the 10' run from my SSB tuner to the backstay? What I had on the SSB was GTO-15??? Thanks Bruce "Brian Whatcott" wrote in message ... I recommend checking with suppliers' specifications for cable construction materials: solid or stranded? solid or foam insulation? %coverage of shield? Tape wrap? Non-acid outer sheath? before blindly implementing Larry's recommendation below on choosing cables. Yes: let's call it a reality check. Brian W On Sat, 17 Jan 2004 05:54:58 GMT, (Larry W4CSC) wrote: ... 55' mainmast has a Shakespeare 1/2 wave VHF antenna on top with about 75' of RG-58A/U military surplus cable/// If I had to start from scratch, and couldn't buy a 500' roll of surplus RG-58A/U for $10 at my local thrift shop... I recommend using VERY flexible, and reliable, Polyethelene-cored, finely stranded center conductor RG-58A/U (not RG-58/U which has a solid center conductor) for your purpose. All those fancy loss charts mean nothing when the fancy foam cables are pulled through a sharp turn, somewhere. Hell, you can wind RG-58A/U in a hangman's noose and it'll still work great! REALITY CHECK!! You could but it wouldn't have the insulation capabilities of the GTO-15 that was there in the first place. the installer used GTO-15 for a reason, can you figure out why? When you do you will have answered your own question. Bruce in alaska -- add a 2 before @ |
VHF cable type?
To those that say a few db extra cable loss does not make any
difference consider the following: Every time you double the height of your VHF antenna you gain 6 db in signal strength. 6 db signal strength increase at 30 miles accounts for about 3 extra miles in range. The amount of loss you have in the cable or because of low antenna height effects the receiver the same as it does the transmitter. With an extra 6 db of cable loss you will hear 3 miles less at 30 miles. When you add antenna height you pick up signal gain from added height but also increase cable loss due to longer antenna cable length. There will be a point with a given type of cable that when you double the height to gain another 6 db you will also lose 6 db in cable loss. As an example with RG58 at 6 db loss per 100 feet, if you were at 100 feet and went to 200 feet antenna height you would pick up 6 db from height but would also loose 6 db in additional cable loss. If you continued to use RG58 it would do no good to increase the antenna height at that point. At lower, more practical heights, that are associated with boats the same problem exists but to a lesser extent. Because you have not reached the gain / loss (height / cable loss) at lower heights you still have a gain when you increase antenna height. But if you use better cable you can realize more of the height advantage than with higher loss cable. Remember, every little few db of gain or loss helps. They all add up. You could reduce your power a few watts and loose a couple of db. You could use higher loss cable and loose a couple of db. You could mount your antenna a little lower and loose a few more db. Pretty soon you have some significant loss. Will you notice the difference in signal strength when signals are good, no. Can you still talk, sure. Can you talk as far, no. To my way of thinking why leave a few db of signal strength laying on the deck when all you have to do is use a little better cable. That is probably the cheapest way of all in gaining a few db of signal strength. Regards Gary On Sun, 18 Jan 2004 06:15:40 -0500, "Bruce" wrote: Brian and Gary...good stuff. Now understanding the loss of power, it would make sense to get an amp (Idon't think it would be legal) or have a second line run to the spreader on the mizzen.That would drop the run down to 30' and a corresponding increase in power. Thanks for you help Bruce "Gary Schafer" wrote in message .. . This is the same Larry that says that he has a 150 watt VHF amplifier to switch in the antenna line if he can't be heard. Yet he recommends using lossy rg58 cable. Old surplus stuff at that! When cable ages it does not always do so gracefully. The dielectric breaks down and the losses can be considerably higher than new cable. For the amount of work involved and the minimal cost of 100 feet of RG8 type cable, use the best NEW cable. RG8 with polyethylene insulation is the way to go unless you have a size restraint. And forget the aluminum wrap shield stuff. You are asking for trouble in the marine environment with aluminum. You do not need "high shielding" for a VHF radio. Foam insulation is not a good idea on a boat though. The center does migrate at bends. It is also very difficult to install connectors on foam cable. The heat from the soldering iron melts the insulation quickly and lets the center wire move to the side. Sometimes even shorting it. Regards Gary On Sat, 17 Jan 2004 18:53:08 GMT, Brian Whatcott wrote: I recommend checking with suppliers' specifications for cable construction materials: solid or stranded? solid or foam insulation? %coverage of shield? Tape wrap? Non-acid outer sheath? before blindly implementing Larry's recommendation below on choosing cables. Yes: let's call it a reality check. Brian W On Sat, 17 Jan 2004 05:54:58 GMT, (Larry W4CSC) wrote: ... 55' mainmast has a Shakespeare 1/2 wave VHF antenna on top with about 75' of RG-58A/U military surplus cable/// If I had to start from scratch, and couldn't buy a 500' roll of surplus RG-58A/U for $10 at my local thrift shop... I recommend using VERY flexible, and reliable, Polyethelene-cored, finely stranded center conductor RG-58A/U (not RG-58/U which has a solid center conductor) for your purpose. All those fancy loss charts mean nothing when the fancy foam cables are pulled through a sharp turn, somewhere. Hell, you can wind RG-58A/U in a hangman's noose and it'll still work great! REALITY CHECK!! |
VHF cable type?
To those that say a few db extra cable loss does not make any
difference consider the following: Every time you double the height of your VHF antenna you gain 6 db in signal strength. 6 db signal strength increase at 30 miles accounts for about 3 extra miles in range. The amount of loss you have in the cable or because of low antenna height effects the receiver the same as it does the transmitter. With an extra 6 db of cable loss you will hear 3 miles less at 30 miles. When you add antenna height you pick up signal gain from added height but also increase cable loss due to longer antenna cable length. There will be a point with a given type of cable that when you double the height to gain another 6 db you will also lose 6 db in cable loss. As an example with RG58 at 6 db loss per 100 feet, if you were at 100 feet and went to 200 feet antenna height you would pick up 6 db from height but would also loose 6 db in additional cable loss. If you continued to use RG58 it would do no good to increase the antenna height at that point. At lower, more practical heights, that are associated with boats the same problem exists but to a lesser extent. Because you have not reached the gain / loss (height / cable loss) at lower heights you still have a gain when you increase antenna height. But if you use better cable you can realize more of the height advantage than with higher loss cable. Remember, every little few db of gain or loss helps. They all add up. You could reduce your power a few watts and loose a couple of db. You could use higher loss cable and loose a couple of db. You could mount your antenna a little lower and loose a few more db. Pretty soon you have some significant loss. Will you notice the difference in signal strength when signals are good, no. Can you still talk, sure. Can you talk as far, no. To my way of thinking why leave a few db of signal strength laying on the deck when all you have to do is use a little better cable. That is probably the cheapest way of all in gaining a few db of signal strength. Regards Gary On Sun, 18 Jan 2004 06:15:40 -0500, "Bruce" wrote: Brian and Gary...good stuff. Now understanding the loss of power, it would make sense to get an amp (Idon't think it would be legal) or have a second line run to the spreader on the mizzen.That would drop the run down to 30' and a corresponding increase in power. Thanks for you help Bruce "Gary Schafer" wrote in message .. . This is the same Larry that says that he has a 150 watt VHF amplifier to switch in the antenna line if he can't be heard. Yet he recommends using lossy rg58 cable. Old surplus stuff at that! When cable ages it does not always do so gracefully. The dielectric breaks down and the losses can be considerably higher than new cable. For the amount of work involved and the minimal cost of 100 feet of RG8 type cable, use the best NEW cable. RG8 with polyethylene insulation is the way to go unless you have a size restraint. And forget the aluminum wrap shield stuff. You are asking for trouble in the marine environment with aluminum. You do not need "high shielding" for a VHF radio. Foam insulation is not a good idea on a boat though. The center does migrate at bends. It is also very difficult to install connectors on foam cable. The heat from the soldering iron melts the insulation quickly and lets the center wire move to the side. Sometimes even shorting it. Regards Gary On Sat, 17 Jan 2004 18:53:08 GMT, Brian Whatcott wrote: I recommend checking with suppliers' specifications for cable construction materials: solid or stranded? solid or foam insulation? %coverage of shield? Tape wrap? Non-acid outer sheath? before blindly implementing Larry's recommendation below on choosing cables. Yes: let's call it a reality check. Brian W On Sat, 17 Jan 2004 05:54:58 GMT, (Larry W4CSC) wrote: ... 55' mainmast has a Shakespeare 1/2 wave VHF antenna on top with about 75' of RG-58A/U military surplus cable/// If I had to start from scratch, and couldn't buy a 500' roll of surplus RG-58A/U for $10 at my local thrift shop... I recommend using VERY flexible, and reliable, Polyethelene-cored, finely stranded center conductor RG-58A/U (not RG-58/U which has a solid center conductor) for your purpose. All those fancy loss charts mean nothing when the fancy foam cables are pulled through a sharp turn, somewhere. Hell, you can wind RG-58A/U in a hangman's noose and it'll still work great! REALITY CHECK!! |
VHF cable type?
On Sun, 18 Jan 2004 23:46:55 GMT, Gary Schafer wrote:
To those that say a few db extra cable loss does not make any difference consider the following: Every time you double the height of your VHF antenna you gain 6 db in signal strength. Never heard this...any sources I can refer to? None of my books suggest this. If true... 5 to 10 feet = +6 dB 10 to 20 feet = 12dB 20 to 40 feet = 18dB 40 to 80 feet = 24dB 80 to 160 feet = 30dB, which is 1000 times the power supplied at the transmitter end of the cable. 6 db signal strength increase at 30 miles accounts for about 3 extra miles in range. Can you please show the calculations? Or a pointer? Thanks, Norm |
VHF cable type?
On Sun, 18 Jan 2004 23:46:55 GMT, Gary Schafer wrote:
To those that say a few db extra cable loss does not make any difference consider the following: Every time you double the height of your VHF antenna you gain 6 db in signal strength. Never heard this...any sources I can refer to? None of my books suggest this. If true... 5 to 10 feet = +6 dB 10 to 20 feet = 12dB 20 to 40 feet = 18dB 40 to 80 feet = 24dB 80 to 160 feet = 30dB, which is 1000 times the power supplied at the transmitter end of the cable. 6 db signal strength increase at 30 miles accounts for about 3 extra miles in range. Can you please show the calculations? Or a pointer? Thanks, Norm |
VHF cable type?
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