Coax Questions

[bill]

Hello to All

I have a question about vhf coax. Has anyone used the "new" PL-259 connectors that are crimped on (not in the traditional since of crimping). They are made by Shakespear (I think). I installed them at four locations on my coax (masthead, radio, and the female jct piece (2)) and my radio will not work. I have conducted a continuity (sp) test and my meter is showing that the shield is some how making contact with the center conductor. That SHOULD NOT be happening!! is that correct???

Thanks for the help and Fair Winds

Bill
Captain Commanding
S/V Rhapsody (the Original)
CD25D #148
Oklahoma Contingent of the NE Fleet, CDSOA, Inc.
Galley Wench S/V Evening Light
<B><U><FONT COLOR="#ff0000" SIZE="+1">Gunnery Officer S/V Evening Light</FONT></B></U>
<A HREF="http://www.applegatemarina.com">Kerr Lake, OK (Oklahoma's Outlet to the Sea)</A>



cd25d@rhapsodysails.com

[Ken Coit]

Bill,

You are absolutely correct, no matter what PL-259 connectors you use, there should not be a short from the shield to the center conductor.

If you have a ham friend with some antenna testing equipment, an old-fashioned grid dip meter would do, you can determine just where that short is and you won't have to disassemble connectors randomly until the short goes away.

Keep on sailing,

Ken Coit
CD/14 #538
CD/36 #84 Parfait
Hailing Port: Raleigh, NC
Sailing from: Beaufort, NC

Hello to All

I have a question about vhf coax. Has anyone used the "new" PL-259 connectors that are crimped on (not in the traditional since of crimping). They are made by Shakespear (I think). I installed them at four locations on my coax (masthead, radio, and the female jct piece (2)) and my radio will not work. I have conducted a continuity (sp) test and my meter is showing that the shield is some how making contact with the center conductor. That SHOULD NOT be happening!! is that correct???

Thanks for the help and Fair Winds

Bill
Captain Commanding
S/V Rhapsody (the Original)
CD25D #148
Oklahoma Contingent of the NE Fleet, CDSOA, Inc.
Galley Wench S/V Evening Light
<B><U><FONT COLOR="#ff0000" SIZE="+1">Gunnery Officer S/V Evening Light</FONT></B></U>
<A HREF="http://www.applegatemarina.com">Kerr Lake, OK (Oklahoma's Outlet to the Sea)</A>

parfaitNOSPAM@nc.rr.com

[John R.]

Ken is absolutely correct. FWIW..... in addition you are far better off with a traditional PL259. It just takes decent soldering to do the job correctly and neat stripping procedures with proper assembly according to instructions supplied with the connectors. They will serve you far better over the long run. Use some dielectric grease or anticorrosive during assembly (after all soldering is completed). When finished wrap the connection tightly with self amalgamating sheet or tape. Some time spent now doing things right will save you a lot of grief down the road. Keep in mind if that antenna lead is shorted when you transmit you can kiss the output section of your radio goodbye. In my opinion quick connects are for houses not boats.

Bill,

You are absolutely correct, no matter what PL-259 connectors you use, there should not be a short from the shield to the center conductor.

If you have a ham friend with some antenna testing equipment, an old-fashioned grid dip meter would do, you can determine just where that short is and you won't have to disassemble connectors randomly until the short goes away.

Keep on sailing,

Ken Coit
CD/14 #538
CD/36 #84 Parfait
Hailing Port: Raleigh, NC
Sailing from: Beaufort, NC

Hello to All

I have a question about vhf coax. Has anyone used the "new" PL-259 connectors that are crimped on (not in the traditional since of crimping). They are made by Shakespear (I think). I installed them at four locations on my coax (masthead, radio, and the female jct piece (2)) and my radio will not work. I have conducted a continuity (sp) test and my meter is showing that the shield is some how making contact with the center conductor. That SHOULD NOT be happening!! is that correct???

Thanks for the help and Fair Winds

Bill
Captain Commanding
S/V Rhapsody (the Original)
CD25D #148
Oklahoma Contingent of the NE Fleet, CDSOA, Inc.
Galley Wench S/V Evening Light
<B><U><FONT COLOR="#ff0000" SIZE="+1">Gunnery Officer S/V Evening Light</FONT></B></U>
<A HREF="http://www.applegatemarina.com">Kerr Lake, OK (Oklahoma's Outlet to the Sea)</A>

[Larry DeMers]

Hi Bill,

Be careful here. An ohmmeter indication of a shorted coax that is **connected** to the antenna, may actually be showing the resistance of the loading coil at the antennas base!! Contrary to the advice given below, a shorted coax does not necessarily mean anything until you can determine if the antenna has this loading coil or not (Metz type antennas usually have these, while the more common Shakespeare antennas do not usually have them. You can tell by looking for a small "can" at the antenna base..there is a coil in that can, and you are measuring across it's resistance since it goes from center conductor to ground (shield)). Now if there is no loading coil:

The newer PL259 connectors are just as subject to assembly errors as the older soldered version is, so make absolutely certain that the shield wires are *all* accounted for before inserting the center conductor into the connector body. The shield must be away from the center section so that when the connector is assembled, it will not force the shield into the center conductor (as will happen if the length of uncovered center dielectric is too long).
Additioinally, soldering of the shield on the older PL259's was hard unless folks had a large wattage gun to solder with..that shield is a huge heat sink afterall. So I have repaired all sorts of errors here. Too much heat applied, melting the center dielectric, splayed out shield wires shorting to the center pin, shields applied unevenly..ie: all the shield is shoved into one corner of the connector, unshielding a major section of the connector, causing RF to escape, and losing some power due to impedance mismatches etc.

In a Soldereed PL259:
Spread the shield out evenly over the circumference of the connector, and track solder it down after the conn. is assembled. Do NOT press down hard with the soldering gun, as that will melt into the dielectric foam insulation of the center cond. Solder well in all four of those connector holes, flowing the solder onto the connector body. Do a good job of soldering the center pin also..clean and brite.

Good Luck,

Larry DeMers
s/v DeLaMer
CD30 Lake Superior

Hello to All

I have a question about vhf coax. Has anyone used the "new" PL-259 connectors that are crimped on (not in the traditional since of crimping). They are made by Shakespear (I think). I installed them at four locations on my coax (masthead, radio, and the female jct piece (2)) and my radio will not work. I have conducted a continuity (sp) test and my meter is showing that the shield is some how making contact with the center conductor. That SHOULD NOT be happening!! is that correct???

Thanks for the help and Fair Winds

Bill
Captain Commanding
S/V Rhapsody (the Original)
CD25D #148
Oklahoma Contingent of the NE Fleet, CDSOA, Inc.
Galley Wench S/V Evening Light
<B><U><FONT COLOR="#ff0000" SIZE="+1">Gunnery Officer S/V Evening Light</FONT></B></U>
<A HREF="http://www.applegatemarina.com">Kerr Lake, OK (Oklahoma's Outlet to the Sea)</A>

demers@sgi.com

[John R]

That is correct about an antenna utilizing a loading coil but I believe Ken's remarks were misunderstood as they were limited to a *coax lead* discussion. At least that is how I read them, perhaps I'm wrong. Shakespere also makes a loading coil antenna such as the Metz. The Metz has proven itself to be a very good quality antenna over the years.

I might point out something very important about coax cable. A *foam* dielectric center conductor insulation in a coax cable has no place on board a boat, it is strictly a land use coax. Boats should only be wired with a *poly* dielectric insulator coax cable. Foam causes all sorts of corrosion and signal loss problems from moisture absorption. Also the poly insulator is more heat resistant than foam and is less susceptible to soldering damage. Usually a 60 watt chisel tip iron and high tin (90 + % tin)solder will solder a PL259 without any difficulties or damages using a quality rosin flux. Make sure the iron tip is well tinned, clean and up to temperature.

Hi Bill,

Be careful here. An ohmmeter indication of a shorted coax that is **connected** to the antenna, may actually be showing the resistance of the loading coil at the antennas base!! Contrary to the advice given below, a shorted coax does not necessarily mean anything until you can determine if the antenna has this loading coil or not (Metz type antennas usually have these, while the more common Shakespeare antennas do not usually have them. You can tell by looking for a small "can" at the antenna base..there is a coil in that can, and you are measuring across it's resistance since it goes from center conductor to ground (shield)). Now if there is no loading coil:

The newer PL259 connectors are just as subject to assembly errors as the older soldered version is, so make absolutely certain that the shield wires are *all* accounted for before inserting the center conductor into the connector body. The shield must be away from the center section so that when the connector is assembled, it will not force the shield into the center conductor (as will happen if the length of uncovered center dielectric is too long).
Additioinally, soldering of the shield on the older PL259's was hard unless folks had a large wattage gun to solder with..that shield is a huge heat sink afterall. So I have repaired all sorts of errors here. Too much heat applied, melting the center dielectric, splayed out shield wires shorting to the center pin, shields applied unevenly..ie: all the shield is shoved into one corner of the connector, unshielding a major section of the connector, causing RF to escape, and losing some power due to impedance mismatches etc.

In a Soldereed PL259:
Spread the shield out evenly over the circumference of the connector, and track solder it down after the conn. is assembled. Do NOT press down hard with the soldering gun, as that will melt into the dielectric foam insulation of the center cond. Solder well in all four of those connector holes, flowing the solder onto the connector body. Do a good job of soldering the center pin also..clean and brite.

Good Luck,

Larry DeMers
s/v DeLaMer
CD30 Lake Superior

Hello to All

I have a question about vhf coax. Has anyone used the "new" PL-259 connectors that are crimped on (not in the traditional since of crimping). They are made by Shakespear (I think). I installed them at four locations on my coax (masthead, radio, and the female jct piece (2)) and my radio will not work. I have conducted a continuity (sp) test and my meter is showing that the shield is some how making contact with the center conductor. That SHOULD NOT be happening!! is that correct???

Thanks for the help and Fair Winds

Bill
Captain Commanding
S/V Rhapsody (the Original)
CD25D #148
Oklahoma Contingent of the NE Fleet, CDSOA, Inc.
Galley Wench S/V Evening Light
<B><U><FONT COLOR="#ff0000" SIZE="+1">Gunnery Officer S/V Evening Light</FONT></B></U>
<A HREF="http://www.applegatemarina.com">Kerr Lake, OK (Oklahoma's Outlet to the Sea)</A>

[John Nuttall]

.....thereby driving the prongs thru the shield and into the core?

Could be a possible source of your problem.....

What size coax are you using...there is a clear plastic shim you are supposed to use on smaller coax. It would help align the coax in the fitting and maybe prevent over crimping. The stupid little o-ring they provide certianly will not go far towards keeping out moisture. The suggestions below are *spot-on*.
John

[Ken Coit]

I am going to hide behind "Oh, I didn't realize the coax was connected to anything." Thanks JohnR for providing that cover. Of course it is, unless the mast is on the ground and the antenna has yet to be connected. Then Larry is, of course, right; you have to worry about what the antenna looks like electrically and if there is a loading coil, a DC measurement will surely show at least one short. On the other hand, a grid dip meter would have shown the antenna resonating at the proper frequency if all was well with the antenna and feed line.

Antenna measurement tools are useful folks. Look at the MFJ web site below if you want to be overwhelmed with tricks of the trade at reasonalbe quality and price. I don't think you will find any antique grid dip meters, but their analyzer is a very decent replacement.

Keep on sailing and transmitting,

Ken Coit, ND7N
CD/14 #538
CD/36 #84 Parfait
Hailing Port: Raleigh, NC
Sailing from: Beaufort, NC

That is correct about an antenna utilizing a loading coil but I believe Ken's remarks were misunderstood as they were limited to a *coax lead* discussion. At least that is how I read them, perhaps I'm wrong. Shakespere also makes a loading coil antenna such as the Metz. The Metz has proven itself to be a very good quality antenna over the years.

I might point out something very important about coax cable. A *foam* dielectric center conductor insulation in a coax cable has no place on board a boat, it is strictly a land use coax. Boats should only be wired with a *poly* dielectric insulator coax cable. Foam causes all sorts of corrosion and signal loss problems from moisture absorption. Also the poly insulator is more heat resistant than foam and is less susceptible to soldering damage. Usually a 60 watt chisel tip iron and high tin (90 + % tin)solder will solder a PL259 without any difficulties or damages using a quality rosin flux. Make sure the iron tip is well tinned, clean and up to temperature.

Hi Bill,

Be careful here. An ohmmeter indication of a shorted coax that is **connected** to the antenna, may actually be showing the resistance of the loading coil at the antennas base!! Contrary to the advice given below, a shorted coax does not necessarily mean anything until you can determine if the antenna has this loading coil or not (Metz type antennas usually have these, while the more common Shakespeare antennas do not usually have them. You can tell by looking for a small "can" at the antenna base..there is a coil in that can, and you are measuring across it's resistance since it goes from center conductor to ground (shield)). Now if there is no loading coil:

The newer PL259 connectors are just as subject to assembly errors as the older soldered version is, so make absolutely certain that the shield wires are *all* accounted for before inserting the center conductor into the connector body. The shield must be away from the center section so that when the connector is assembled, it will not force the shield into the center conductor (as will happen if the length of uncovered center dielectric is too long).
Additioinally, soldering of the shield on the older PL259's was hard unless folks had a large wattage gun to solder with..that shield is a huge heat sink afterall. So I have repaired all sorts of errors here. Too much heat applied, melting the center dielectric, splayed out shield wires shorting to the center pin, shields applied unevenly..ie: all the shield is shoved into one corner of the connector, unshielding a major section of the connector, causing RF to escape, and losing some power due to impedance mismatches etc.

In a Soldereed PL259:
Spread the shield out evenly over the circumference of the connector, and track solder it down after the conn. is assembled. Do NOT press down hard with the soldering gun, as that will melt into the dielectric foam insulation of the center cond. Solder well in all four of those connector holes, flowing the solder onto the connector body. Do a good job of soldering the center pin also..clean and brite.

Good Luck,

Larry DeMers
s/v DeLaMer
CD30 Lake Superior

Hello to All

I have a question about vhf coax. Has anyone used the "new" PL-259 connectors that are crimped on (not in the traditional since of crimping). They are made by Shakespear (I think). I installed them at four locations on my coax (masthead, radio, and the female jct piece (2)) and my radio will not work. I have conducted a continuity (sp) test and my meter is showing that the shield is some how making contact with the center conductor. That SHOULD NOT be happening!! is that correct???

Thanks for the help and Fair Winds

Bill
Captain Commanding
S/V Rhapsody (the Original)
CD25D #148
Oklahoma Contingent of the NE Fleet, CDSOA, Inc.
Galley Wench S/V Evening Light
<B><U><FONT COLOR="#ff0000" SIZE="+1">Gunnery Officer S/V Evening Light</FONT></B></U>
<A HREF="http://www.applegatemarina.com">Kerr Lake, OK (Oklahoma's Outlet to the Sea)</A>

parfait@nc.rr.com

[Larry DeMers]

Ken,

An antenna analyzer is a good idea for someone who is serious about comms, but they are not for the run-of-the-mill, confused by DC electronics, what the heck is ohms law -type sailors. The theory and use of the device is, in my experience at least with the MFJ box you pictured, beyond the range of interest for most average sailors.
There is however a better device for the less technically equipped sailor..that is a SWR meter. Shakespeare makes a neat little one that, once calibrated, will show forward power radiated from the antenna, as well as reflected power from the antenna back to the transmitter (wasted power), due to impedance problems (which in turn are due to poor connections, water infiltration into the coax core, and other specific problems). You simply look at it while transmitting and read the SWR (Standing Wave Ratio..a measure of how much of the generated RF power is actually leaving the antenna, and how much is being wasted), and act if the ratio it shows is other than the desired 1:1 or in reality 1:1.2-1.5. I have one permanently mounted in series with the antenna lead on my VHF. Very useful device.

Cheers,

Larry DeMers
s/v DelaMer
Cape Dory 30

I am going to hide behind "Oh, I didn't realize the coax was connected to anything." Thanks JohnR for providing that cover. Of course it is, unless the mast is on the ground and the antenna has yet to be connected. Then Larry is, of course, right; you have to worry about what the antenna looks like electrically and if there is a loading coil, a DC measurement will surely show at least one short. On the other hand, a grid dip meter would have shown the antenna resonating at the proper frequency if all was well with the antenna and feed line.

Antenna measurement tools are useful folks. Look at the MFJ web site below if you want to be overwhelmed with tricks of the trade at reasonalbe quality and price. I don't think you will find any antique grid dip meters, but their analyzer is a very decent replacement.

Keep on sailing and transmitting,

Ken Coit, ND7N
CD/14 #538
CD/36 #84 Parfait
Hailing Port: Raleigh, NC
Sailing from: Beaufort, NC

That is correct about an antenna utilizing a loading coil but I believe Ken's remarks were misunderstood as they were limited to a *coax lead* discussion. At least that is how I read them, perhaps I'm wrong. Shakespere also makes a loading coil antenna such as the Metz. The Metz has proven itself to be a very good quality antenna over the years.

I might point out something very important about coax cable. A *foam* dielectric center conductor insulation in a coax cable has no place on board a boat, it is strictly a land use coax. Boats should only be wired with a *poly* dielectric insulator coax cable. Foam causes all sorts of corrosion and signal loss problems from moisture absorption. Also the poly insulator is more heat resistant than foam and is less susceptible to soldering damage. Usually a 60 watt chisel tip iron and high tin (90 + % tin)solder will solder a PL259 without any difficulties or damages using a quality rosin flux. Make sure the iron tip is well tinned, clean and up to temperature.

Hi Bill,

Be careful here. An ohmmeter indication of a shorted coax that is **connected** to the antenna, may actually be showing the resistance of the loading coil at the antennas base!! Contrary to the advice given below, a shorted coax does not necessarily mean anything until you can determine if the antenna has this loading coil or not (Metz type antennas usually have these, while the more common Shakespeare antennas do not usually have them. You can tell by looking for a small "can" at the antenna base..there is a coil in that can, and you are measuring across it's resistance since it goes from center conductor to ground (shield)). Now if there is no loading coil:

The newer PL259 connectors are just as subject to assembly errors as the older soldered version is, so make absolutely certain that the shield wires are *all* accounted for before inserting the center conductor into the connector body. The shield must be away from the center section so that when the connector is assembled, it will not force the shield into the center conductor (as will happen if the length of uncovered center dielectric is too long).
Additioinally, soldering of the shield on the older PL259's was hard unless folks had a large wattage gun to solder with..that shield is a huge heat sink afterall. So I have repaired all sorts of errors here. Too much heat applied, melting the center dielectric, splayed out shield wires shorting to the center pin, shields applied unevenly..ie: all the shield is shoved into one corner of the connector, unshielding a major section of the connector, causing RF to escape, and losing some power due to impedance mismatches etc.

In a Soldereed PL259:
Spread the shield out evenly over the circumference of the connector, and track solder it down after the conn. is assembled. Do NOT press down hard with the soldering gun, as that will melt into the dielectric foam insulation of the center cond. Solder well in all four of those connector holes, flowing the solder onto the connector body. Do a good job of soldering the center pin also..clean and brite.

Good Luck,

Larry DeMers
s/v DeLaMer
CD30 Lake Superior

demers@sgi.com

[Larry DeMers]

John,

The output section of most all VHF transcievers nowdays have "Crowbar-like" circuits built into them that control output wattage by antenna impedance. In other words, it will not allow a shorted antenna to be fully loaded..nor will it try to load an open antenna. It is self-protecting of these two situations, so your warning is accurate for old equipment, but not equipment that has been bought in the past 5-10 years, except for the odd cheap-o products that are based on old technology.

Larry DeMers
s/v DeLaMer

Ken is absolutely correct. FWIW..... in addition you are far better off with a traditional PL259. It just takes decent soldering to do the job correctly and neat stripping procedures with proper assembly according to instructions supplied with the connectors. They will serve you far better over the long run. Use some dielectric grease or anticorrosive during assembly (after all soldering is completed). When finished wrap the connection tightly with self amalgamating sheet or tape. Some time spent now doing things right will save you a lot of grief down the road. Keep in mind if that antenna lead is shorted when you transmit you can kiss the output section of your radio goodbye. In my opinion quick connects are for houses not boats.

Bill,

You are absolutely correct, no matter what PL-259 connectors you use, there should not be a short from the shield to the center conductor.

If you have a ham friend with some antenna testing equipment, an old-fashioned grid dip meter would do, you can determine just where that short is and you won't have to disassemble connectors randomly until the short goes away.

Keep on sailing,

Ken Coit
CD/14 #538
CD/36 #84 Parfait
Hailing Port: Raleigh, NC
Sailing from: Beaufort, NC

Hello to All

I have a question about vhf coax. Has anyone used the "new" PL-259 connectors that are crimped on (not in the traditional since of crimping). They are made by Shakespear (I think). I installed them at four locations on my coax (masthead, radio, and the female jct piece (2)) and my radio will not work. I have conducted a continuity (sp) test and my meter is showing that the shield is some how making contact with the center conductor. That SHOULD NOT be happening!! is that correct???

Thanks for the help and Fair Winds

Bill
Captain Commanding
S/V Rhapsody (the Original)
CD25D #148
Oklahoma Contingent of the NE Fleet, CDSOA, Inc.
Galley Wench S/V Evening Light
<B><U><FONT COLOR="#ff0000" SIZE="+1">Gunnery Officer S/V Evening Light</FONT></B></U>
<A HREF="http://www.applegatemarina.com">Kerr Lake, OK (Oklahoma's Outlet to the Sea)</A>

demers@sgi.com

[Larry DeMers]

John,

Yes, foam or goretex dielectric absorbs water over time -as does the polyemet dielectric. They all absorb water, do to the construction itself. The wicking action is due to the shield more than the dielectric it seems, although I have read that the closeness of the components in the cable makes for the wicking action. I have had ham antennas up at home since I was 12, all fed with coax of one type or another, from RG8u/x and it's variants to semi-rigid coax, air core coax, special VHF lowloss aircore coax for 2 meter Moonbounce experiments etc.

Do you think that rain on land is any less absorbed than rain on the ocean?? There is no dielectric specified for marine use as far as I am aware of..please let me know if you have specific info to the contrary. The marine spec. calls for the center core to be pretinned to prevent or mitigate oxidation of the copper conductor, as well as the shield must be pretinned for the same reason.
Water absorbtion is a problem with any coax that was not properly installed with a drip loop at the top of the mast, and proper self-amalgamating tape placed over the connectors body, and the coax end itself. I also like to seal the end of the coax with warmed up silicon sealant. It gets wicked up into the braid a little, which seals it off better.

That said, my boats VHF cable is probably original equipment, but it needs replacement, as I see the SWR climbing each year, despite cleaning the contacts on the pL259's. Disassembly shows the shield has started to turn dark as it oxidizes. Cutting back on the cable is not possible due to lack of any spare cable in the mast. So the mast gets a complete rewire job next spring. New deck and spreader lights, new windspeed sensor and all new cabling. Will keep the existing antenna, as it seems to have great range for a coilless, 1/4 wave end fed antenna.

Hey John, ever seen a solution to get the Am-Fm antenna up to the top of the mast for better range and coverage of FM radio? I know this is low priority on most peoples minds, but since I am rewiring the mast, I was thinking of installing a retractable am-fm antenna up at the truck. The idea being that it would extend itself only when the stereo is powered up..like it does in your car. The problems with this idea are that I need to find a power antenna with a small form factor and completely sealed from the weather. I know I have seen one that uses what appears to be a screwdrive to raise and lower the antenna, so the whole package is very small in diameter..maybe 2 1/2" x 4" for the motor section. The motor itself would be located within the mast, and the antenna would popup thru the top of the mast head fitting. Since the running rigging is external to the mast, that should leave the interior fairly clear of obstructions (?). Crazy idea probably, but it has my interest for now. ;^). THe problem with a mast top am-fm antenna is coupling of the VHF sig to the am-fm antenna, as well as detuning the VHF antenna, since the antennas are within 1/4 wavelength of each other. The idea was to use a motorized am-fm antenna so that it is out of the picture when not in use. There is the VHF-Am/Fm antenna combiner of course, but they are very lossy to both signals that they carry, so that is not a great choice.
Any ideas?

Larry DeMers

That is correct about an antenna utilizing a loading coil but I believe Ken's remarks were misunderstood as they were limited to a *coax lead* discussion. At least that is how I read them, perhaps I'm wrong. Shakespere also makes a loading coil antenna such as the Metz. The Metz has proven itself to be a very good quality antenna over the years.

I might point out something very important about coax cable. A *foam* dielectric center conductor insulation in a coax cable has no place on board a boat, it is strictly a land use coax. Boats should only be wired with a *poly* dielectric insulator coax cable. Foam causes all sorts of corrosion and signal loss problems from moisture absorption. Also the poly insulator is more heat resistant than foam and is less susceptible to soldering damage. Usually a 60 watt chisel tip iron and high tin (90 + % tin)solder will solder a PL259 without any difficulties or damages using a quality rosin flux. Make sure the iron tip is well tinned, clean and up to temperature.

Hi Bill,

Be careful here. An ohmmeter indication of a shorted coax that is **connected** to the antenna, may actually be showing the resistance of the loading coil at the antennas base!! Contrary to the advice given below, a shorted coax does not necessarily mean anything until you can determine if the antenna has this loading coil or not (Metz type antennas usually have these, while the more common Shakespeare antennas do not usually have them. You can tell by looking for a small "can" at the antenna base..there is a coil in that can, and you are measuring across it's resistance since it goes from center conductor to ground (shield)). Now if there is no loading coil:

The newer PL259 connectors are just as subject to assembly errors as the older soldered version is, so make absolutely certain that the shield wires are *all* accounted for before inserting the center conductor into the connector body. The shield must be away from the center section so that when the connector is assembled, it will not force the shield into the center conductor (as will happen if the length of uncovered center dielectric is too long).
Additioinally, soldering of the shield on the older PL259's was hard unless folks had a large wattage gun to solder with..that shield is a huge heat sink afterall. So I have repaired all sorts of errors here. Too much heat applied, melting the center dielectric, splayed out shield wires shorting to the center pin, shields applied unevenly..ie: all the shield is shoved into one corner of the connector, unshielding a major section of the connector, causing RF to escape, and losing some power due to impedance mismatches etc.

In a Soldereed PL259:
Spread the shield out evenly over the circumference of the connector, and track solder it down after the conn. is assembled. Do NOT press down hard with the soldering gun, as that will melt into the dielectric foam insulation of the center cond. Solder well in all four of those connector holes, flowing the solder onto the connector body. Do a good job of soldering the center pin also..clean and brite.

Good Luck,

Larry DeMers
s/v DeLaMer
CD30 Lake Superior

Hello to All

I have a question about vhf coax. Has anyone used the "new" PL-259 connectors that are crimped on (not in the traditional since of crimping). They are made by Shakespear (I think). I installed them at four locations on my coax (masthead, radio, and the female jct piece (2)) and my radio will not work. I have conducted a continuity (sp) test and my meter is showing that the shield is some how making contact with the center conductor. That SHOULD NOT be happening!! is that correct???

Thanks for the help and Fair Winds

Bill
Captain Commanding
S/V Rhapsody (the Original)
CD25D #148
Oklahoma Contingent of the NE Fleet, CDSOA, Inc.
Galley Wench S/V Evening Light
<B><U><FONT COLOR="#ff0000" SIZE="+1">Gunnery Officer S/V Evening Light</FONT></B></U>
<A HREF="http://www.applegatemarina.com">Kerr Lake, OK (Oklahoma's Outlet to the Sea)</A>

demers@sgi.com

[John R.]

I use a 8" AM/FM/TV dish antenna just below the masthead. It is about an inch thich at the center and tapers to about 1/2" all around the edge. It is also super lightweight. I installed it long ago and it has performed beautifully from day one. I might add it has a small signal amplification unit that I mounted inside the nav station, from there the AM/FM coax and the TV coax separate. It also has a signal strength indicator built into that amplification box.

Seems to me setting up some sort of motorized antenna system at the masthead is going to do nothing more than achieve increase weight aloft for you. I don't know what you would be gaining by installing a complex system like that. There are several nice simple marinized antenna systems on the market that are easy to install and don't add unnecessary weight aloft. That is what I would advise you to use. Plenty of boats run around with just simple deck mounted whip antennas and they seem to work well as you are probably aware.

True that all open ended conductors can eventually absorb some moisture but nonetheless there remains a significant difference between foam insulator material and poly as far as resistance to absorption and moisture passage is concerned. I can't think of one marine wire manufacturer that uses foam dielectric or goretex in their coax cable. I seal the shield conductor with waterproof lanolin based dielectric grease before I complete the PL-259 plug assembly. The grease is thin enough that with a finger you can actually force the grease up under the coax cover a small ways to practically terminate any moisture absorption or you invert the coax and gradually inject CX (Corrosion X) with a hypodermic and it will penetrate way up into the coax by capillary action. Both methods have worked very well and I have tested it long term when I've replaced plugs and cut an extra couple inchs or so up from the coax end and it was like new. No signs of deterioration in the shielding conductor. I too seal all connectors with self amalgamating tape and can't stress enough the importance of that practice.

John,

Yes, foam or goretex dielectric absorbs water over time -as does the polyemet dielectric. They all absorb water, do to the construction itself. The wicking action is due to the shield more than the dielectric it seems, although I have read that the closeness of the components in the cable makes for the wicking action. I have had ham antennas up at home since I was 12, all fed with coax of one type or another, from RG8u/x and it's variants to semi-rigid coax, air core coax, special VHF lowloss aircore coax for 2 meter Moonbounce experiments etc.

Do you think that rain on land is any less absorbed than rain on the ocean?? There is no dielectric specified for marine use as far as I am aware of..please let me know if you have specific info to the contrary. The marine spec. calls for the center core to be pretinned to prevent or mitigate oxidation of the copper conductor, as well as the shield must be pretinned for the same reason.
Water absorbtion is a problem with any coax that was not properly installed with a drip loop at the top of the mast, and proper self-amalgamating tape placed over the connectors body, and the coax end itself. I also like to seal the end of the coax with warmed up silicon sealant. It gets wicked up into the braid a little, which seals it off better.

That said, my boats VHF cable is probably original equipment, but it needs replacement, as I see the SWR climbing each year, despite cleaning the contacts on the pL259's. Disassembly shows the shield has started to turn dark as it oxidizes. Cutting back on the cable is not possible due to lack of any spare cable in the mast. So the mast gets a complete rewire job next spring. New deck and spreader lights, new windspeed sensor and all new cabling. Will keep the existing antenna, as it seems to have great range for a coilless, 1/4 wave end fed antenna.

Hey John, ever seen a solution to get the Am-Fm antenna up to the top of the mast for better range and coverage of FM radio? I know this is low priority on most peoples minds, but since I am rewiring the mast, I was thinking of installing a retractable am-fm antenna up at the truck. The idea being that it would extend itself only when the stereo is powered up..like it does in your car. The problems with this idea are that I need to find a power antenna with a small form factor and completely sealed from the weather. I know I have seen one that uses what appears to be a screwdrive to raise and lower the antenna, so the whole package is very small in diameter..maybe 2 1/2" x 4" for the motor section. The motor itself would be located within the mast, and the antenna would popup thru the top of the mast head fitting. Since the running rigging is external to the mast, that should leave the interior fairly clear of obstructions (?). Crazy idea probably, but it has my interest for now. ;^). THe problem with a mast top am-fm antenna is coupling of the VHF sig to the am-fm antenna, as well as detuning the VHF antenna, since the antennas are within 1/4 wavelength of each other. The idea was to use a motorized am-fm antenna so that it is out of the picture when not in use. There is the VHF-Am/Fm antenna combiner of course, but they are very lossy to both signals that they carry, so that is not a great choice.
Any ideas?

Larry DeMers

That is correct about an antenna utilizing a loading coil but I believe Ken's remarks were misunderstood as they were limited to a *coax lead* discussion. At least that is how I read them, perhaps I'm wrong. Shakespere also makes a loading coil antenna such as the Metz. The Metz has proven itself to be a very good quality antenna over the years.

I might point out something very important about coax cable. A *foam* dielectric center conductor insulation in a coax cable has no place on board a boat, it is strictly a land use coax. Boats should only be wired with a *poly* dielectric insulator coax cable. Foam causes all sorts of corrosion and signal loss problems from moisture absorption. Also the poly insulator is more heat resistant than foam and is less susceptible to soldering damage. Usually a 60 watt chisel tip iron and high tin (90 + % tin)solder will solder a PL259 without any difficulties or damages using a quality rosin flux. Make sure the iron tip is well tinned, clean and up to temperature.

Hi Bill,

Be careful here. An ohmmeter indication of a shorted coax that is **connected** to the antenna, may actually be showing the resistance of the loading coil at the antennas base!! Contrary to the advice given below, a shorted coax does not necessarily mean anything until you can determine if the antenna has this loading coil or not (Metz type antennas usually have these, while the more common Shakespeare antennas do not usually have them. You can tell by looking for a small "can" at the antenna base..there is a coil in that can, and you are measuring across it's resistance since it goes from center conductor to ground (shield)). Now if there is no loading coil:

The newer PL259 connectors are just as subject to assembly errors as the older soldered version is, so make absolutely certain that the shield wires are *all* accounted for before inserting the center conductor into the connector body. The shield must be away from the center section so that when the connector is assembled, it will not force the shield into the center conductor (as will happen if the length of uncovered center dielectric is too long).
Additioinally, soldering of the shield on the older PL259's was hard unless folks had a large wattage gun to solder with..that shield is a huge heat sink afterall. So I have repaired all sorts of errors here. Too much heat applied, melting the center dielectric, splayed out shield wires shorting to the center pin, shields applied unevenly..ie: all the shield is shoved into one corner of the connector, unshielding a major section of the connector, causing RF to escape, and losing some power due to impedance mismatches etc.

In a Soldereed PL259:
Spread the shield out evenly over the circumference of the connector, and track solder it down after the conn. is assembled. Do NOT press down hard with the soldering gun, as that will melt into the dielectric foam insulation of the center cond. Solder well in all four of those connector holes, flowing the solder onto the connector body. Do a good job of soldering the center pin also..clean and brite.

Good Luck,

Larry DeMers
s/v DeLaMer
CD30 Lake Superior

[John R.]

Not quite sure what you are refering to by the "Crowbar-like" description. If it gets into electronics product engineering jive then don't bother expounding on it for me.....not interested to that degree but am to a degree that it applies to marine applications.

Anyway, I'm wondering what current brands of radios have this *feature* you describe in their output section because I have an aquaintance that has a radio (doa) (Raytheon I believe) less than two years old that did blow when his coax shorted from chafe where it passed through the mast and he had transmitted unknowingly and that was the end. He has since purchased a new unit (Icom) since it was not a warranty situation. Can you mention some brands that you know for a fact have this failsafe you mention, it would be good for people to know exactly what brands provide this safety net. I've not seen it mentioned in marketing materials I've looked at.

John,

The output section of most all VHF transcievers nowdays have "Crowbar-like" circuits built into them that control output wattage by antenna impedance. In other words, it will not allow a shorted antenna to be fully loaded..nor will it try to load an open antenna. It is self-protecting of these two situations, so your warning is accurate for old equipment, but not equipment that has been bought in the past 5-10 years, except for the odd cheap-o products that are based on old technology.

Larry DeMers
s/v DeLaMer

Ken is absolutely correct. FWIW..... in addition you are far better off with a traditional PL259. It just takes decent soldering to do the job correctly and neat stripping procedures with proper assembly according to instructions supplied with the connectors. They will serve you far better over the long run. Use some dielectric grease or anticorrosive during assembly (after all soldering is completed). When finished wrap the connection tightly with self amalgamating sheet or tape. Some time spent now doing things right will save you a lot of grief down the road. Keep in mind if that antenna lead is shorted when you transmit you can kiss the output section of your radio goodbye. In my opinion quick connects are for houses not boats.

Bill,

You are absolutely correct, no matter what PL-259 connectors you use, there should not be a short from the shield to the center conductor.

If you have a ham friend with some antenna testing equipment, an old-fashioned grid dip meter would do, you can determine just where that short is and you won't have to disassemble connectors randomly until the short goes away.

Keep on sailing,

Ken Coit
CD/14 #538
CD/36 #84 Parfait
Hailing Port: Raleigh, NC
Sailing from: Beaufort, NC

[Larry DeMers]

John,

Well then I won't waste my time describing how it works since you state that you are not interested in that.
Suffice it to say that the entire line of Icom radios, and Standard Marine radios (and others that I have run into also) have and currently use some form of VSWR control to keep the output from being damaged by shorted or open antennas. Icom uses a circuit called an SWR Sensor tied into a APC or Automatic Power Control to guard against Opens and Shorts. They have used this from DAY 1 of their product line.
Now repeated use of the radio in these compromised conditions will cause problems with the radio. This may be what happened to your friend who had the radio fail when he had a shorted antenna. -is he particularly stubborn or thick? heh...

To be certain, I did check with the tech service of Standard and Icom, and they verified what I have said here and before...simply that most to all of the Marine VHF Radios produced in the past 10 years have some form of output protection associated with them such that an open or a shorted antenna will not take out the transmitter section unless the operator repeats the offense several times.

Cheers,

Larry DeMers
s/v DeLaMer
Cape Dory 30 Lake Superior

Not quite sure what you are refering to by the "Crowbar-like" description. If it gets into electronics product engineering jive then don't bother expounding on it for me.....not interested to that degree but am to a degree that it applies to marine applications.

Anyway, I'm wondering what current brands of radios have this *feature* you describe in their output section because I have an aquaintance that has a radio (doa) (Raytheon I believe) less than two years old that did blow when his coax shorted from chafe where it passed through the mast and he had transmitted unknowingly and that was the end. He has since purchased a new unit (Icom) since it was not a warranty situation. Can you mention some brands that you know for a fact have this failsafe you mention, it would be good for people to know exactly what brands provide this safety net. I've not seen it mentioned in marketing materials I've looked at.

John,

The output section of most all VHF transcievers nowdays have "Crowbar-like" circuits built into them that control output wattage by antenna impedance. In other words, it will not allow a shorted antenna to be fully loaded..nor will it try to load an open antenna. It is self-protecting of these two situations, so your warning is accurate for old equipment, but not equipment that has been bought in the past 5-10 years, except for the odd cheap-o products that are based on old technology.

Larry DeMers
s/v DeLaMer

Ken is absolutely correct. FWIW..... in addition you are far better off with a traditional PL259. It just takes decent soldering to do the job correctly and neat stripping procedures with proper assembly according to instructions supplied with the connectors. They will serve you far better over the long run. Use some dielectric grease or anticorrosive during assembly (after all soldering is completed). When finished wrap the connection tightly with self amalgamating sheet or tape. Some time spent now doing things right will save you a lot of grief down the road. Keep in mind if that antenna lead is shorted when you transmit you can kiss the output section of your radio goodbye. In my opinion quick connects are for houses not boats.

Bill,

demers@sgi.com

[John R.]

Yep, that's enough of a technical explanation without disecting the contents of the radio. I would venture to say that because this is not an absolute protection (as you noted) that in the event the mic were keyed more than once (limit unknown I'm assuming) then it could be quite feasible for a person with a new generation radio to still blow the unit with an existing short in the coax or antenna unknowingly by repeated attempts to transmit rather than just a single attempt.

It is not hard to see how this could easily occur in the real world.

Since that appears to be the case then I would think the warning about possibly blowing the output section of the radio with a direct short in the coax/antenna is still an issue that needs to be understood by everyone and remains valid enough even though the manufacturers have taken limited steps to reduce the situation from happening initially but certainly not completely.

John,

Well then I won't waste my time describing how it works since you state that you are not interested in that.
Suffice it to say that the entire line of Icom radios, and Standard Marine radios (and others that I have run into also) have and currently use some form of VSWR control to keep the output from being damaged by shorted or open antennas. Icom uses a circuit called an SWR Sensor tied into a APC or Automatic Power Control to guard against Opens and Shorts. They have used this from DAY 1 of their product line.
Now repeated use of the radio in these compromised conditions will cause problems with the radio. This may be what happened to your friend who had the radio fail when he had a shorted antenna. -is he particularly stubborn or thick? heh...

To be certain, I did check with the tech service of Standard and Icom, and they verified what I have said here and before...simply that most to all of the Marine VHF Radios produced in the past 10 years have some form of output protection associated with them such that an open or a shorted antenna will not take out the transmitter section unless the operator repeats the offense several times.

Cheers,

Larry DeMers
s/v DeLaMer
Cape Dory 30 Lake Superior

Not quite sure what you are refering to by the "Crowbar-like" description. If it gets into electronics product engineering jive then don't bother expounding on it for me.....not interested to that degree but am to a degree that it applies to marine applications.

Anyway, I'm wondering what current brands of radios have this *feature* you describe in their output section because I have an aquaintance that has a radio (doa) (Raytheon I believe) less than two years old that did blow when his coax shorted from chafe where it passed through the mast and he had transmitted unknowingly and that was the end. He has since purchased a new unit (Icom) since it was not a warranty situation. Can you mention some brands that you know for a fact have this failsafe you mention, it would be good for people to know exactly what brands provide this safety net. I've not seen it mentioned in marketing materials I've looked at.

John,

The output section of most all VHF transcievers nowdays have "Crowbar-like" circuits built into them that control output wattage by antenna impedance. In other words, it will not allow a shorted antenna to be fully loaded..nor will it try to load an open antenna. It is self-protecting of these two situations, so your warning is accurate for old equipment, but not equipment that has been bought in the past 5-10 years, except for the odd cheap-o products that are based on old technology.

Larry DeMers
s/v DeLaMer

[Larry DeMers]

Good ideas John.
The reason for the attempt to get an antenna up top the mast head is the infernal racket from the LINK 2000 and LINK 10 monitors. They are horribly noisy RF wise, and ruin AM-FM reception (not to mention Ham and SSB) despite adding toroids, rf LC filters, and rerouting wiring in shielded cable. I have reduced the infernal racket about 5dB, which is about a 75% reduction in what I had before. But the AM-FM antenna right now is a Shakespeare 1 meter whip mounted to the coach roof, on the starboard side. Too close to the computers in the LINK monitors. Since field strength decays with the cube of the distance, getting 30-40 ft. away should make the rcvr immune to the RF from the LINK/s.
So ok, the masthead is a good place then, in distance. But two antennas in parallel is a huge problem in detuning of both, so to avoid that, I am going to try out a motorized antenna. They are lite..only about 1.5 lbs or so. But your point about weight aloft is a good one to be paid heed to.
The tv antenna you use does come with a splitter? Is this the typical round tv antenna carried in West Marine?

I'll look into them too. Could be a good solution too, although, in my case I would put the amp as far from the LINK panel as possible.

I must love gimmicky stuff. The idea of that antenna poking up when called for (ala your car) was kind of appealing on a technical level. But you are right..complicated, perhaps unnecessarily so.

Thanks,

Larry DeMers
s/v DeLaMer

I use a 8" AM/FM/TV dish antenna just below the masthead. It is about an inch thich at the center and tapers to about 1/2" all around the edge. It is also super lightweight. I installed it long ago and it has performed beautifully from day one. I might add it has a small signal amplification unit that I mounted inside the nav station, from there the AM/FM coax and the TV coax separate. It also has a signal strength indicator built into that amplification box.

Seems to me setting up some sort of motorized antenna system at the masthead is going to do nothing more than achieve increase weight aloft for you. I don't know what you would be gaining by installing a complex system like that. There are several nice simple marinized antenna systems on the market that are easy to install and don't add unnecessary weight aloft. That is what I would advise you to use. Plenty of boats run around with just simple deck mounted whip antennas and they seem to work well as you are probably aware.

True that all open ended conductors can eventually absorb some moisture but nonetheless there remains a significant difference between foam insulator material and poly as far as resistance to absorption and moisture passage is concerned. I can't think of one marine wire manufacturer that uses foam dielectric or goretex in their coax cable. I seal the shield conductor with waterproof lanolin based dielectric grease before I complete the PL-259 plug assembly. The grease is thin enough that with a finger you can actually force the grease up under the coax cover a small ways to practically terminate any moisture absorption or you invert the coax and gradually inject CX (Corrosion X) with a hypodermic and it will penetrate way up into the coax by capillary action. Both methods have worked very well and I have tested it long term when I've replaced plugs and cut an extra couple inchs or so up from the coax end and it was like new. No signs of deterioration in the shielding conductor. I too seal all connectors with self amalgamating tape and can't stress enough the importance of that practice.

John,

Yes, foam or goretex dielectric absorbs water over time -as does the polyemet dielectric. They all absorb water, do to the construction itself. The wicking action is due to the shield more than the dielectric it seems, although I have read that the closeness of the components in the cable makes for the wicking action. I have had ham antennas up at home since I was 12, all fed with coax of one type or another, from RG8u/x and it's variants to semi-rigid coax, air core coax, special VHF lowloss aircore coax for 2 meter Moonbounce experiments etc.

Do you think that rain on land is any less absorbed than rain on the ocean?? There is no dielectric specified for marine use as far as I am aware of..please let me know if you have specific info to the contrary. The marine spec. calls for the center core to be pretinned to prevent or mitigate oxidation of the copper conductor, as well as the shield must be pretinned for the same reason.
Water absorbtion is a problem with any coax that was not properly installed with a drip loop at the top of the mast, and proper self-amalgamating tape placed over the connectors body, and the coax end itself. I also like to seal the end of the coax with warmed up silicon sealant. It gets wicked up into the braid a little, which seals it off better.

That said, my boats VHF cable is probably original equipment, but it needs replacement, as I see the SWR climbing each year, despite cleaning the contacts on the pL259's. Disassembly shows the shield has started to turn dark as it oxidizes. Cutting back on the cable is not possible due to lack of any spare cable in the mast. So the mast gets a complete rewire job next spring. New deck and spreader lights, new windspeed sensor and all new cabling. Will keep the existing antenna, as it seems to have great range for a coilless, 1/4 wave end fed antenna.

Hey John, ever seen a solution to get the Am-Fm antenna up to the top of the mast for better range and coverage of FM radio? I know this is low priority on most peoples minds, but since I am rewiring the mast, I was thinking of installing a retractable am-fm antenna up at the truck. The idea being that it would extend itself only when the stereo is powered up..like it does in your car. The problems with this idea are that I need to find a power antenna with a small form factor and completely sealed from the weather. I know I have seen one that uses what appears to be a screwdrive to raise and lower the antenna, so the whole package is very small in diameter..maybe 2 1/2" x 4" for the motor section. The motor itself would be located within the mast, and the antenna would popup thru the top of the mast head fitting. Since the running rigging is external to the mast, that should leave the interior fairly clear of obstructions (?). Crazy idea probably, but it has my interest for now. ;^). THe problem with a mast top am-fm antenna is coupling of the VHF sig to the am-fm antenna, as well as detuning the VHF antenna, since the antennas are within 1/4 wavelength of each other. The idea was to use a motorized am-fm antenna so that it is out of the picture when not in use. There is the VHF-Am/Fm antenna combiner of course, but they are very lossy to both signals that they carry, so that is not a great choice.
Any ideas?

Larry DeMers

That is correct about an antenna utilizing a loading coil but I believe Ken's remarks were misunderstood as they were limited to a *coax lead* discussion. At least that is how I read them, perhaps I'm wrong. Shakespere also makes a loading coil antenna such as the Metz. The Metz has proven itself to be a very good quality antenna over the years.

I might point out something very important about coax cable. A *foam* dielectric center conductor insulation in a coax cable has no place on board a boat, it is strictly a land use coax. Boats should only be wired with a *poly* dielectric insulator coax cable. Foam causes all sorts of corrosion and signal loss problems from moisture absorption. Also the poly insulator is more heat resistant than foam and is less susceptible to soldering damage. Usually a 60 watt chisel tip iron and high tin (90 + % tin)solder will solder a PL259 without any difficulties or damages using a quality rosin flux. Make sure the iron tip is well tinned, clean and up to temperature.

demers@sgi.com