New radio and coaxial install........

[Rotten Ricky]

Illusion,

Thanks for your pearls of wisdom!

I would normally go for high end stuff, especially on an inaccessible place like a mast, but being as this is essentially free cable, of a higher rating (even if of a dubious brand) and for a boat I may not have much longer, I will try the 0.4" RG8U. I will find some good ends for it and as a former electrician I will do a fastidious, well-sealed job on them.

I really appreciate the suggestions of all,

Rotten Ricky.

[hellosailor]

Ricky-
You can go crazy trying to check out coax for a vhf on the mast. You need low signal loss around 160MHz, which is not difficult. But ideally, you'd also want a stranded center conductor (not solid, so it can flex) and you'd want it all tinned to resist the marine moisture. And you wouldn't want the typical high performance foam dielectric, because foams absorb moisture AND they crush and deform over time, which creates more losses.
What you've got will work, most likely the thicker cable being more robust, but Rat Shack caling also usually was not 100% shielded IIRC and you want a 100% shield.
Offhand, no, I don't recall what we used and I'm not going to chase down the many online coax comparison test charts. The good stuff is more expensive, but that's cheaper in the long run.

As for hanging the cable, you need drip loops, and not to radius it too tightly, and you need to spread the pressure where it is attached in mast, so you don't pinch the cable. If you don't support it every ten feet or so, it eventually stretches out from gravity, which is why some folks will say replace it every 5-10 years regardless.

There are metal mesh gadgets, they look like Chinese finger traps or heart stents, that tighten down over a 3-6" length of coax, grabbing it firmly without pinching it. You may find them online, or at a professional electrical supply house. I can never remember the name of them.

The SWR meter is much better than nothing--but it only tells you the reflected signal strength AT THE METER. So if there is 80' of cable going from the meter up to the mast? You might be sending 25 watts "up", but 15 watts could be getting reflected down--and you might still see a perfect 1:1 SWR because those 80' of a poor cable with high losses, were also eating up the reflected signal. Most of us just have to live with that, a pro should have an antenna analyzer that actually can take that into account.

But you do the best you can, given time and wallet constraints, and that's all you can do.

[Bycrick]

The original military specification for REAL RG-8 cable was withdrawn decades ago. It had detailed requirements: jacket composition, wire sizes, shield coverage, center insulator design, etc.

Once the spec was officially withdrawn, anybody could make a piece of cable that sort-of looked like RG-8 and label it as such. The jacket could be recycled soda bottles, the shield coverage could be 60%, the wires could be reprocessed copper, all of which made for lower manufacturing costs.

Good coax from a reputable manufacturer is relatively inexpensive. You can buy Times Microwave LMR-400UF for under $1.25/foot. Or Belden 9913. You can get various styles, PVC or polyethylene jacket, foam or solid dielectric, single or double shield in several flavors, tinned or not, solid or stranded center conductor. Each construction has pluses and minuses.

But using old, inexpensive cable is probably a poor way to save a few bucks when you consider the time and effort to install it properly.

Use good PL-259 connectors. Even the best are well under $10/each. Soldering them used to be the undisputed right way, but it took a heavy iron and lots of practice. Now, I prefer the ones that solder the center conductor and crimp the shield. The connector ideally should be matched to the cable. For example, you can use a generic PL-259 solder-on connector on LMR-400UF, but there’s also several connectors for that specific cable, which can be important if you use crimp connectors.

[GTom]

Originally Posted by Pete7

Slight thread drift, but are you saying I wasted my time fitting this RG8X:

https://www.saltyjohn.com/product/cable-kit-20m/

Going for the same in the Metz antenna kit .

Done some quick maths: someone recommended Hyperflex 10, which is even better than RG8/RG213 at about 4.8dB/100m or 1.45dB/100'. John's RG8X (Belden?) is claims 12dB/100m, which gives about 1.3dB advantage to the thicker cable (. But at what cost?? Need to redrill the deck, even replace the deck gland, drill further new holes down below - all for nothing, because I might screw up the RG213 to antenna connection while the RG8x kit comes already fitted.

Benefit of a "plain" RG213 (about 8.5dB/100m) would be half of that, around 0.7dB/15%.

[Pete7]

Also you will need plugs that will fit RG213 as that is quite a thick cable.

I managed to get a single 20m cable from masthead to the radio without any breaks and sufficient spare next the mast support to allow it to be cut in future to take the mast down.

Salty John comes with a good reputation so trust his supply of cable. Buying off the internet, I couldn't be sure of the quality.

Pete