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RG-8X vs. RG-8U coax?
- Thread starter Steve H
- Start date
looks like your confusing rg58/u with rg8/u. rg8/u was the old mil spec that is now replaced by rg213/u, it's just under half inch in diameter (10.3mm) and handles around 1kw or more with a good swr.
the main trouble is rg8/u is no longer a military spec cable, therefore any cable carrying that designation now is either very very old or fake with no quality control. with a shelf life of around 20 years (due to ncv jacket) rg8/u if it was real would be on the very edge of its sell by date if not past it.
Also the dielectric was generally solid polyethylene and has no chance of melting at 50w.
As others have said rg11/u is a similar sized cable too rg213/u but its 75 ohms.
Back in the late '60's and early '70's we used RG8/u exclusively. At some point in the '70's, RG8/u was delisted from MIL-SPEC-C17, and replaced by RG213/u. We switched over. It is still being sold. Stay away from any foam type cable as it deforms when bent amd is not physically rubust. Not to put too fine a point on it - it's crap. Stay awau from "RG8/u type".. it's also crap.
RG8X is a smaller cable about 1/4" dia. We use it exclusively for short runs, under 25' and for short jumpers and interconnects, where power is under 150W. Anything over 150W gets RG213/u.
RG8X is a smaller cable about 1/4" dia. We use it exclusively for short runs, under 25' and for short jumpers and interconnects, where power is under 150W. Anything over 150W gets RG213/u.
I think I have to agree with 74IN, the type/size of coax just isn't as important on HF as people have made it out to be in the last several years. The characteristic impedance is the important part, the other characteristics -can- be important, but usually aren't. The published power ratings are not very accurate or specific. That's dependent on the state of 'tune' of the antenna/load on the end of it. If that antenna/load isn't at least close to 50 ohms with no reactances (the biggy), that coax can be damaged.
I can't disagree from experience about that 'RG-174' stuff, but except for VERY short runs of it (as in inches), I don't want any part of it. Just to hard to deal with, connectors etc.
Even RG-58 is as useful as the 'larger' cables. I would be 'picky' about who made it, where it came from, but for short runs, less than 100 feet, it will work fine in most applications (even at high power).
Nothing wrong with using 'larger' cables, but it's certainly not always necessary in the common HF situations.
- 'Doc
(74IN - hate to ruin your reputation by agreeing with you, but...)
I can't disagree from experience about that 'RG-174' stuff, but except for VERY short runs of it (as in inches), I don't want any part of it. Just to hard to deal with, connectors etc.
Even RG-58 is as useful as the 'larger' cables. I would be 'picky' about who made it, where it came from, but for short runs, less than 100 feet, it will work fine in most applications (even at high power).
Nothing wrong with using 'larger' cables, but it's certainly not always necessary in the common HF situations.
- 'Doc
(74IN - hate to ruin your reputation by agreeing with you, but...)
I agree with DOC and 74IN.
I have used both here for HF. I notice no difference between the RG8U or the RG8X mini stuff.
Do not think either type will work if you have a big mismatch at the feed point.
I have ran 1KW through the mini 8 coax, into a forced current fed array for 40 meters. Never had any problems but then the antenna was resonant with no big impedance mis-match.
Specs and MIL specs do have their place. Specs tell you what the manufacture recommendations are usually very consertative.
MIL SPEC means you will pay two to three times the amount for the same product as it has been tested to meet GOVT specs.
On Hf I do not believe you will be able to hear the difference between the two on a 100 foot fun of either coax.
I have used both here for HF. I notice no difference between the RG8U or the RG8X mini stuff.
Do not think either type will work if you have a big mismatch at the feed point.
I have ran 1KW through the mini 8 coax, into a forced current fed array for 40 meters. Never had any problems but then the antenna was resonant with no big impedance mis-match.
Specs and MIL specs do have their place. Specs tell you what the manufacture recommendations are usually very consertative.
MIL SPEC means you will pay two to three times the amount for the same product as it has been tested to meet GOVT specs.
On Hf I do not believe you will be able to hear the difference between the two on a 100 foot fun of either coax.
Wow...thanks for the answers again. After reading the last few posts, I'll probably go with an 18-ft. length of 213 cable. It's the same price as RG8U for that length. And it's polyvinyl insulated, instead of poly-foam.
My setup is far from spectacular: just a tuned Cobra 29 LTD hooked to a good base antenna (probably an I-Max) and a good regulated power supply.
I was just concerned about the thickness/durability of the cable, laying against a hot roof in July, then getting iced over in January, then getting blown around and wet in April. And the uv rays all year round. None of the cable will be underground, but I'd say that it's punishment will be just as bad, if not worse.
My setup is far from spectacular: just a tuned Cobra 29 LTD hooked to a good base antenna (probably an I-Max) and a good regulated power supply.
I was just concerned about the thickness/durability of the cable, laying against a hot roof in July, then getting iced over in January, then getting blown around and wet in April. And the uv rays all year round. None of the cable will be underground, but I'd say that it's punishment will be just as bad, if not worse.
UV and weather protection.
You ever get a hole in your water hose and have to throw it away?
RG8u or any .405 diameter coax will slide right inside that old water hose.
Then solder your connector on the end of it after you slide it through that old water hose. Zip tie or hose clamp the end of the water hose to the coax. Water hose will lay for years in the sun, Imagine how long it will protect that coax from uv?
You ever get a hole in your water hose and have to throw it away?
RG8u or any .405 diameter coax will slide right inside that old water hose.
Then solder your connector on the end of it after you slide it through that old water hose. Zip tie or hose clamp the end of the water hose to the coax. Water hose will lay for years in the sun, Imagine how long it will protect that coax from uv?
All antenna connections from the shack to antenna, in my shack, are done with LMR-400 made by Times Microwave. Damn good coax. If you use LMR-400 get the real stuff not the ePay stuff that says LMR-400 type. If it says type it means it has been over salt water to get here. In the shack, any jumpers are made using 8X.
RG-8U is still made to day by Belden. If you consider it as old when it comes off the line then I guess it can be called old cable. Belden is still a very viable company. In fact they were the original manufacturer of the RG-8U cable. The main difference between the RG-8 and the RG-8U is that the U means that it can be burried underground where RG-8 would deteriorate real quick.
Hey Mack, I thought you had the new Vector 4000, maybe I got you corn'fused with Dirtyfatboy.
I think we have the same antenna but when I purchased it the ad called it an lw-150 but the box says otherwise.
I honestly don't know the difference between the 2.
i think you'll find Belden actually use their own inhouse model numbers and don't use any rg numbers, what they do is tell you what their cable is equivalent too (or in some cases slightly superior too) in RG spec.
Belden do make high quality cables, but at a very high price premium compared to others who make RG cables ( now obsolete designation) or MIL-C-17 as its now known,up till recently the cables carried a mil-c-17 code usually with d,e,or f prefix which changed as the mil spec was slightly changed (also gives an indication of the cables age if you know when the specs changed,the later the letter the later it was made),
now they carry a M17 designation with a / followed by a number to designate which type it is. for example M17/28 = RG58c/u, M17/74 = RG213/u, M17/75 = RG214/u i don't know where you get the U designation stands for underground burial,as far as i am aware the U designation means universal. if you want to learn about MIL-C17 coax cables check out these links:
List Mil Specs - DSCC
M17 / MIL-C-17 Coaxial Cable from Allied Wire & Cable - Manufacturer of Custom Cables and Coaxial Cable Assemblies
This one lists the MIL spec/RG cross. Quick cross reference.
M17/2-RG6 - M17/77-RG216 from Allied Wire & Cable - Distributor of M17 Coaxial Cable
M17/2-RG6 - M17/77-RG216 from Allied Wire & Cable - Distributor of M17 Coaxial Cable
Nothing at all wrong with using 75 ohm cable with a "50 ohm radio". The feedpoint impedance of a properly installed dipole is a lot closer to 75 ohms than to 50.