Can I replace a 6ft piece of RG-58U between my VHF radio and the mast? With an 8 ft p

[Brian.D]

WOTNAME I usually end my comments with JMHO. I appear to have forgotten to do that this time. Apologies.

[Wotname]

Originally Posted by Brian.D

WOTNAME I usually end my comments with JMHO. I appear to have forgotten to do that this time. Apologies.

Absolutely no apologies necessary!

We have different backgrounds and different experiences. You are posting from yours and I am posting from mine. They different - that is all!

I'm good with different and I reckon you are also .

[ferrailleur]

heard of swan neck (goose neck) to run cables from mast to underdeck with no connection.... cannot find any link to a supplier of those?

[n5ama]

Ok, I got my N barrel connector. :<}

What sealant is recommended for the installation at deck level? The “white stuff” that is sealing the old UHF barrel seems to work but I have no idea what that is. Given the quality of the original installation, I would not expect anything great.

Thanks in advance for any advise.

[gatorman49]

Temflex covered with 3M 88. N connectors are great but not necessary at 157 MHz. Further, how many marine VHF antennas do you see with N female connectors? It is always nice to have one piece of cable between ant and radio if possible. RG-8 or 213 is a little less fragile than 8X but not as flexible. An improperly installed connector is your enemy. If you aren’t experienced in this regard, find someone who is.

And don’t forget that spare antenna that attaches to railing when masthead ant fails.

[carlwk3c]

Originally Posted by AZ-Oldguy

I know very little about VHF and antennas, is length critical? I am working on replacing the headliner inside my pilothouse and the wires and cable that run to the radio are just a mess. I would like to tidy them up and to do so I need the antenna cable that goes to the Masthead antenna to be a little longer. There is a six-foot piece of cable that goes from the back of the radio down behind the cabinetry near the electric panel. There it connects to the cable that comes out of the base of the mast. Can I just replace that 6 foot RG-58U cable with an 8-foot one so I have a little extra length to create a tidy run of wiring to the radio? Where would I buy that cable? The 6-foot cable has a male connector on one end and a female connector on the other. If I could get an 8 ft version of the same thing I would be smiling. Let me know what I need to know. Thanks everybody

If the antenna and the other cable and. Inns tors present a proper impedance match, the length is irrelevant, except that more cable has more loss. The difference between 6’ and 8’ is essentially zero.

[skenn_ie]

A little extra length won't make any noticable difference. Good, impedance matched connections are fairly critical though. You MUST use matched connectors, and fit them correctly. At worst, a bad connection could kill your transmitter. At best, they will reduce the signal strength both receiving and transmitting.

[skenn_ie]

For thru-deck, cable glands are better than sealant.

[n5ama]

Thanks but I need a barrel connector to disconnect at the base of the mast. I’m replacing a existing uhf barrel connector there and need to reseal the new fitting.

[Austin351]

Originally Posted by Jim Cate

Please add citations for this statement. There have been several posts here on CF in the past citing the opposite opinion, including one with something like thirty connectors of varying types in series with no measurable loss. One fairly pessimistic figure that is generally accepted is 0.1 db per connector, but even that figure is hard to support. Several sources suggest more like 0.01 db in the HF realm. Either of these figures means that the loss is completely insignificant.

The loss from a barrel connector and two PL-239 males is infinitesimal, but the chances for damaging a cable whilst unstepping/restepping a mast are significant... to say nothing of the inconvenience involved.

Protecting against moisture is important, as I posted upthread.

Jim

Speaking from 25 years in the wireless industry, the connectors are the weakest link (most dB loss). Hook it up to a spectrum analyzer and you will see loss at every connection. That being said, with the short run (less than 100' overall) of RG and the low frequency, it is all moot.

[betwys1]

Originally Posted by Jim Cate

Please add citations for this statement. There have been several posts here on CF in the past citing the opposite opinion, including one with something like thirty connectors of varying types in series with no measurable loss. One fairly pessimistic figure that is generally accepted is 0.1 db per connector, but even that figure is hard to support. Several sources suggest more like 0.01 db in the HF realm. Either of these figures means that the loss is completely insignificant.

The loss from a barrel connector and two PL-239 males is infinitesimal, but the chances for damaging a cable whilst unstepping/restepping a mast are significant... to say nothing of the inconvenience involved.

Protecting against moisture is important, as I posted upthread.

Jim

People who cannot measure losses in UHF connectors at 150 MHz are not really trying. Look at this experimental check on connector loss:

https://www.hamradio.me/connectors/u...t-results.html

bottom line - replace UHF with ANY other connector! N BNC etc., etc.
Tape up connectors with flexible self-amalgamating tape or waterproof putty.

Brian W (for what it's worth: FCC GROL/Radar endorsement)

https://www.fcc.gov/wireless/bureau-...icense-program

[Dubbinchris]

I didn’t read all the posts, but I’ve learned the hard way that the “marine cable” from MPD is NOT marine grade. Marine simply means white in color really. The inner copper is NOT tin coated as it should be.

[Bycrick]

"Boat cable" isn’t "required" to be tinned. A properly crimped connection is gas-tight, so you won’t get moisture into the crimp area itself. While the tinned wire itself might me marginally more corrosion resistant than non-tinned wire, if you get enough moisture into the coax to cause corrosion of the wire, it’s likely to have much worse effects on the dielectric than on the wire. This is particularly true for foam-dielectric low-loss cables like LMR400 as compared to solid-dielectric cable like RG-213, because the foam dielectric can absorb more moisture more quickly.

[Wotname]

Originally Posted by n5ama

Ok, I got my N barrel connector. :<}

What sealant is recommended for the installation at deck level? The “white stuff” that is sealing the old UHF barrel seems to work but I have no idea what that is. Given the quality of the original installation, I would not expect anything great.

Thanks in advance for any advise.

I am assuming you are asking about external sealant. If so, use 3M Scotch® Tape 23 which is a self amalgamating rubber resin tape. It is often over wrapped with a standard vinyl electrical tape. https://www.3m.com.au/3M/en_AU/compa...0584000&rt=rud

I have used this method extensively for all sorts of external RF connectors in extreme weather conditions - remote satellite ground stations in tropical areas (cyclonic / hurricane conditions), off-shore oil/gas antenna installations as well as my mast connectors .

Applied properly, it remains watertight for decades however it needs to be cut off if disassembled is required. Cutting the tape off is a straightforward exercise as is re-applying new tape (the connector and coax remains undamaged).

Although not normally recommended, I have found a smear of low pressure silicon grease (like Dow Corning #4) on the threads of the connector gives a warm fuzzy feeling to have a belt and braces approach .

[n5ama]

Originally Posted by Wotname

I am assuming you are asking about external sealant. If so, use 3M Scotch® Tape 23 which is a self amalgamating rubber resin tape. It is often over wrapped with a standard vinyl electrical tape. https://www.3m.com.au/3M/en_AU/compa...0584000&rt=rud

I have used this method extensively for all sorts of external RF connectors in extreme weather conditions - remote satellite ground stations in tropical areas (cyclonic / hurricane conditions), off-shore oil/gas antenna installations as well as my mast connectors .

Applied properly, it remains watertight for decades however it needs to be cut off if disassembled is required. Cutting the tape off is a straightforward exercise as is re-applying new tape (the connector and coax remains undamaged).

Although not normally recommended, I have found a smear of low pressure silicon grease (like Dow Corning #4) on the threads of the connector gives a warm fuzzy feeling to have a belt and braces approach .

I use Temflex and 3M super 88 on the coax connector and the connector barrel. The Temflex is wrapped around the coax, the connector and then finally the upper part of the barrel connector that sits above the deck. I then wrap 3M super 88 tape over this to contain the Temflex in place.

What I'm asking about is the seal between the barrel connector as it goes through the fiberglass deck. The "stuff" that seals against water entering the interior of the boat around the flange of the barrel connector.