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Discussion Starter #1
Hi,
We are installing a antenna splitter for our AIS system we just purchased.
We have about 55 foot of cable Ancor RG 8X Coaxial Cable coming down the mast.
Then the splitter.
Then 20' of RG 8X Coaxial Cable coming from the splitter and going to the AIS unit.

Now can we add a 6' length of rg58a/u 50ohm cable we bought from Vesper Marine to the RG 8X Coaxial Cable coming down the mast so we can put the splitter in a better location without degrading the signal?

Then add another 6' rg58a/u 50ohm extension onto the splitter and then connect it to the 20 foot section going to the AIS without degrading the signal?
Thanks,
Chip
 

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Anytime you put anything in a transmit/receive cable you are degrading the signal and adding a place where corrosion can get in the line and make problems for the system. Use as few connectors or splitters as possible.
 
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You will be fine with this. The loss through the RG59 you plan will total a whopping 0.4db. For comparison, if you used quality LMR400 for those connections instead, you would have a 0.2db loss. Either way, it will be inconsequential mixed with the 3db loss of 75' of RG8X. FWIW, you get a 3db gain on receive with the vesper.

Mark
 

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Capta is correct in theory about signal degradation with connectors, and dead on about corrosion. However, the loss through good connectors is unmeasurable in practice. Put in as many as you need and you won't be able to measure a difference. Corrosion is the biggie. If they are not in a dry area, follow good practices with coax seal.

Mark
 

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As Capta said the fewer the connection the better, also RG-8x has less loss than RG-58.

Ideally, when using a splitter, one coax to the antenna and one coax to each radio.

Every connection extra you add, adds two points of potential, and actual loss one entering the adapter and one exiting the adapter.

Personally I would can the RG-58 and do single runs of RG-8x or better from each radio to the splitter. As colemj above stated.
 

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Discussion Starter #7
Hi,
I'll try to use only the x8 coming from the mast and the x8 going to the VHF.
It puts the splitter in a tough place where there is no room. I am inserting the splitter where two two cables join now.
To put the splitter just a couple feet away in a better place then I would need to extend each cable at least a foot which means adding all the extra connections. It may be possible to fit the splitter in where it joins just those two cables.
On the upside the cables have been there now for 8 or nine years and the the connector to them only has slight corrosion on one end.
They are in a dry spot.
Chip
 

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As Capta said the fewer the connection the better, also RG-8x has less loss than RG-58.

Ideally, when using a splitter, one coax to the antenna and one coax to each radio.

Every connection extra you add, adds two points of potential, and actual loss one entering the adapter and one exiting the adapter.

Personally I would can the RG-58 and do single runs of RG-8x or better from each radio to the splitter. As colemj above stated.
I didn't say that. I said just the opposite - that he will be fine with the connectors and RG58 he is planning.

The loss difference over 12' of RG58 pigtails compared to 12' of RG8X pigtails is 0.07db. There will be no practical or measurable difference between them.

The OP stated his desire for doing this was to put the splitter in a better position. That implies that using smaller, more flexible coax will be helpful, as well as the splitter will be in a better environment. If this is true, then those reasons are far more important to ruggedness and operation than preserving 0.07db.

While connectors add a theoretical potential loss, they do not add a measurable or actual one, unless they have been done incorrectly, or poor quality connectors have been used. It is pretty much an old wive's tale. There is a guy on here who posts infrequently, but always about radio topics, who is a professional in this area with lots of measurement equipment. As an experiment, he put together a long string of a dog's breakfast of connectors - including BNC and other seemingly inappropriate ones - and could measure no meaningful loss through them. So adding a couple of good quality, well-made connectors in a system for pure convenience sake is just fine.

I would consider it preferable to running a single piece of coax from the mast top throughout the whole boat. Pulling all that, and putting it back in, every time the mast is pulled would be a pain. Also preferable to having a piece of equipment located in a poorer or less convenient environment just for the sake of not using connectors.

But even if the OP just wanted to use 12' of RG58 and multiple connectors only for the pure fun of it, he will be fine.

Mark
 

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This makes a lot of sense. When I retired Haleakulas mast 12 years ago using RG8X at SV Aispicious suggestion I placed a connection box after the entrance of the mast to the interior. This allowed just disconnecting the cable easily whenever the mast would be pulled.

The run from there of the second RG8X cable went to the area where all the electric panels were . At that time at its terminus we addded a splitter although only one was used. Later on we added the Vesper AISB and it was as simple as plug and play,

Periodically I disconnected all junctions and inspect as well as tidy them up for any debris or corrosion.
 

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I didn't say that. I said just the opposite - that he will be fine with the connectors and RG58 he is planning.

The loss difference over 12' of RG58 pigtails compared to 12' of RG8X pigtails is 0.07db. There will be no practical or measurable difference between them.

The OP stated his desire for doing this was to put the splitter in a better position. That implies that using smaller, more flexible coax will be helpful, as well as the splitter will be in a better environment. If this is true, then those reasons are far more important to ruggedness and operation than preserving 0.07db.

While connectors add a theoretical potential loss, they do not add a measurable or actual one, unless they have been done incorrectly, or poor quality connectors have been used. It is pretty much an old wive's tale. There is a guy on here who posts infrequently, but always about radio topics, who is a professional in this area with lots of measurement equipment. As an experiment, he put together a long string of a dog's breakfast of connectors - including BNC and other seemingly inappropriate ones - and could measure no meaningful loss through them. So adding a couple of good quality, well-made connectors in a system for pure convenience sake is just fine.

I would consider it preferable to running a single piece of coax from the mast top throughout the whole boat. Pulling all that, and putting it back in, every time the mast is pulled would be a pain. Also preferable to having a piece of equipment located in a poorer or less convenient environment just for the sake of not using connectors.

But even if the OP just wanted to use 12' of RG58 and multiple connectors only for the pure fun of it, he will be fine.

Mark
My comment was on your suggestion to use LMF 400, sorry for the confusion and my lack of clarification, it was late and an edit. again sorry should have reread what I was stating.

I will agree to disagree with your statements on connectors and the numbers however, as my knowledge is first hand and yours appears to be second hand, but I will agree that at 100 to 200 Mhz there is probably no discernible difference, measurable...depends on your test equipment.

To state that a BNC is inappropriate connect is also a misnomer, as it is good for general use up to 2 Ghz so for VHF and AIS they are perfectly fine. In fact BNC and TNC only differ in that BNC is Bayoneted and TNC is threaded, they are both NC connectors.

Also stating that the difference between RG-58 and RG-8X at 12 feet being 0.07 dB is only true for the manufacturer you choose, as RG-58 and RG-8X are sizes and do not necessarily impart a standard of lose, in fact they are not standards at all they are simply sizes as previously stated. What does this mean in the big picture of things is that the losses per 100 feet at a given frequency vary from manufacturer to manufacturer, even between Model/Type within a manufacturer take Belden 8240 and Belden 9201 both are RG-58 using the 12 foot length previously stated and at 161 Mhz at 12.5 watts to simulate AIS transmission, the 8240 has 0.593 dB of loss, to put this into wattage the output at the other end of the 12 foot cable would be at 10.904 watts. For the 9201 the results are 0.64 dB of loss and an output power of 10.787 watts. Same size cable same length but 0.117 watts difference. Why is this important 2 fold all losses are additive, duh and these are the losses over only 12 feet of cable as the length increases the difference in loss will to as it is a function of distance.

My point is not all coax cable manufacturers build to the same specification there are good, Times Microwave Systems, and bad Chinese won hung low brand. One cannot say that all RG-58 has exactly x loss difference compared to all RG-8X, one has to know the manufacturer and the model/type of the the RG-58 and RG-8X, then and only then can one say that the loses at x feet is x dB for these two specific cables.

BTW I used the following web site for the calculations Coax Loss Calculator I also used a perfect 1:1 VSWR as to only compare "ideal cables"

What can be said that in general one will have less losses using RG-8X as apposed to RG-58, and if tight corners are an issue why not use 90 degree connectors, it is what they where designed for.

colemj you are correct in a perfect world a single cable from antenna to radio is best, being that we live in the the real world that next best option is to limit the number of connections, this limits the number of potential failure points/ water intrusion/ points for corrosion. So in general keep the number of coax cable to the absolute minimum.
 

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I will agree to disagree with your statements on connectors and the numbers however, as my knowledge is first hand and yours appears to be second hand, but I will agree that at 100 to 200 Mhz there is probably no discernible difference, measurable...depends on your test equipment.
I'm not sure about the 1st/2nd hand comment. I actually have the exact same system as the OP, with the same desire for having the splitter in a convenient place, and both LMR400 and RG58 pigtails to/from it. I removed the LMR400 and replaced with RG58 recently because I wanted to put the splitter in a particular location/position where the LMR400 was proving problematic. 90* connectors don't help at all, unless one uses 5-6 of them with even more pigtails to make the bends and twists. Anyway, there has been no practical real-world difference between the short LMR400 and RG58 pigtails in this application. I don't see why it would for the OP's identical application.

To state that a BNC is inappropriate connect is also a misnomer, as it is good for general use up to 2 Ghz so for VHF and AIS they are perfectly fine. In fact BNC and TNC only differ in that BNC is Bayoneted and TNC is threaded, they are both NC connectors.
My point about appropriateness was in regard to usage and environment. BNC is not a common marine connector for VHF, and it is difficult to seal properly and maintain.

My point is not all coax cable manufacturers build to the same specification there are good, Times Microwave Systems, and bad Chinese won hung low brand. One cannot say that all RG-58 has exactly x loss difference compared to all RG-8X, one has to know the manufacturer and the model/type of the the RG-58 and RG-8X, then and only then can one say that the loses at x feet is x dB for these two specific cables.
Sure, one can pick specific manufacturer/model cables to make any point they want. Choose two and make your point; choose another two and make my point. But for the specific question posted by the OP, the difference between whatever brand/model RG8X, and whatever brand/model RG58, he has will in the real world not make a lick of difference.

If using the RG58 over RG8X means he can place the splitter in a better environment, with better access, and better ease of doing so, then this is by far the better choice over counting tenths of decibels.

What can be said that in general one will have less losses using RG-8X as apposed to RG-58, and if tight corners are an issue why not use 90 degree connectors, it is what they where designed for.
Why stop the logic there? Our previous boat was all wired with Heliax - even the pigtails. Where is the dignity line for what losses are acceptable? Is that line so defined that 12' of RG-58 falls on a different side than 12' of RG-8X? To stick to a general statement that there are less losses with X than with Y, so one should use all X requires the person making the statement to define and defend a specific level of acceptable loss. Otherwise, there is no answer other than pull it all out and rewire with Heliax, or whatever the lowest loss made.

In the OP's presented case, I think counting db is counting angels dancing on pinheads.

Mark
 

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It is a matter of proportion. Yes, adding more connectors and longer coax will add loss. But in your implementation: the added loss is very small. Perfect should not be the enemy of good.

PL-259 connectors are inferior to other connectors: BNC, type N, and TNC. PL-259s are often called "UHF" connectors, and they don't deserve that name. They are lossy in the VHF band starting at about 70 MHz. However, in the VHF marine band, the loss isn't substantial.

Avoid "solderless" PL-259 connectors that are often included with antennas. They depend on a press-fit connection that will fail through corrosion. Making this problem worse is that PL-259 connectors are not water tight. Add a few drops of seawater inside, a little time, and you have a ruined connection. That connector won't even pass DC current, let alone RF. Always solder PL-259 connectors that you assemble yourself, or find someone who knows how.

Patrick
N8QH
 

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Always solder PL-259 connectors that you assemble yourself, or find someone who knows how.

Patrick
N8QH
I have recently been using solder/crimp connectors and prefer this over all solder for a couple of reasons. First, it isn't always convenient to solder - like swinging around at the top of the mast. The tradeoff is that you do have to solder the interior wire, but that is much faster, easier, and fool-proof than soldering the shield. So doable at the top of the mast. Second, some coax is tricky to solder the shield. For example, LMR400 foam insulation can be easily damaged with too much heat.

I started doing this with trepidation, but am finding I like these solder/crimp connectors better. They certainly are easier to make, and seem more fool-proof.

Of course, a good weather-proof seal is essential regardless.

Mark
 

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I have recently been using solder/crimp connectors and prefer this over all solder for a couple of reasons. First, it isn't always convenient to solder - like swinging around at the top of the mast. The tradeoff is that you do have to solder the interior wire, but that is much faster, easier, and fool-proof than soldering the shield. So doable at the top of the mast. Second, some coax is tricky to solder the shield. For example, LMR400 foam insulation can be easily damaged with too much heat.

I started doing this with trepidation, but am finding I like these solder/crimp connectors better. They certainly are easier to make, and seem more fool-proof.

Of course, a good weather-proof seal is essential regardless.

Mark
I have only used soldered connectors, for the reason Patrick listed. What is the brand of crimp/solder connectors you have good experiences with? I presume that is for PL259?
 

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Oh yeah - you need a specific crimp tool for these. Not expensive, but you can't just squeeze them with vice grips...

Mark
The PL259??

Tough little sucker that is!! Thats not the antenna connector? I can do those with solder but the PL259 is difficult and I took it into the Raymarine dude who charged me $10 for the joblette. Best $10 Ive spent on that setup :)


Mark :)
 
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