Choose the Wrong Coax Cable for Ham Radio
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- Опубликовано: 6 дек 2023
- We know that CHEAP is often not so good. But what happens if you chose the wrong coax for you installation? What is the loss? How do you work out what coax you should buy? How do you work out the loss? This quick video solves this issue.
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Buy once, cry once. Antenna is #1, Coax/Feed is #2, everything else is way down on the list of priorities.
This should be an answer to one of the questions on the General test. Bravo!
Ok, well, for some, cry any/buy none. There is a balance.
Also it's a good idea to use double screened coax to reduce breakthrough interference. Especially if you have the coax near any other wires in the shack, or parallel runs for example.
Great to see someone from my generation enjoying ham radio too. 😊
Great info Cal !!!!
Another parameter could be jacket material, I chose Messi Paoloni Extraflex Bury which has UV shielded polyethylene jacket and is suitable for direct burial and outdoor use.
When people ask I always tell them to buy the best, usually name brand, coax they can afford. I have used so many different kinds it's hard to remember them all. I finally was able to run 120ft of lmr400 to my Classic and 75ft of rg213 to my efhw. Great success with both setups and no issues since the installations 2 years ago. I use a 50ft piece of M&P Ultraflex 7 for portable setups because I wanted to use something I could do HF and VHF with that was a little more flexible. I took a 75ft piece of rg213, cut it in half and put some of the screw on connectors like you did the video on. My old pieces of rg8x are in the box as backups but will probably never get used. Thanks for another fun and informative video!
The only coaxcable I use is Messi & Paoloni Ultraflex-13 (for hf and vhf/uhf) Distance from shack to antenna's is about 45 meters. The loss for transmitting can be solved by using more output power :-) But for me the loss on trancieved signal is more important. I have very good results with Messi & Paoloni. Other coaxcable I have used are Belden H-1000 and Aircom Premium. These are also exellent cables, but I think not as good as Messi & Paoloni, and very important, not as flexibel as Messi & Paoloni. 73 PD4PS
Agreed.. The only comparison I could make is Ecoflex 15. The numbers look almost identical.
I remember when i got back into radios earler this year & got my first ticket i bought 5-6 different peaces of coax from amazon & ebay an even one local & Every Single Peace was junk so i did my research & found M&P Coax & Connectors & i have ben running their Hyperflex 10 sahara for my VHF/UHF with their Great Evo Connectors & Haven't Looked Back. Now All my Coax Is M&P as well as all my Connectors is all EVO Connectors Very Good Stuff IMHO
G'day Callum,
Just subscribed to your channel, I can't believe I've not watched any of your videos before.
That's quite mind-blowing when you think about the amount of power you finally end up with at the antenna end with some types of coax.
Cheers,
Mike T.
Hello Mike - and welcome!
being a ham for 60 years I kind of figured this stuff is well know by everyone..........apparently not...........too bad they don't include it in the license tests as it is much more usefull than a lot of what's tested.....some poor guy studies hard and passes his tests, gets on the air with "100 watts & a wire" fed with 100' for $10 RG-58 and makes 4 contacts, gets discouraged and that's it for him..........Cheers from New England to Old England, Mike, K1FNX near Boston......
Nice one, useful video . Mark.
I usually pick the lowest loss for highest frequency for what I'm doing, which is usually 10m band. I often find the Messi & Paoloni is my best option. I've got Airborne 10 and Hyper Flex 10 running to 3 different antennas. Another antenna I'm just using some ABR LMR400 simply because I had the exact length I needed for my 4th antenna.
Great video.
This is why for short run of 20m or less we use a coax (on H.F) and for long runs you better use open balanced feedline.
Good coax is great and important as the antenna you use, yet it could be expensive for long run applications and there is where the open feedline shines, this balanced feedline could be made DIY at a very low cost and the extreme low loss over LONG runs could make it the beter option for many.
Many folks can't use balanced feeder. I can't (for instance) because I am restricted to a 4 inch pipe and no overhead lines allowed. Having been a dedicated previous owner of a massive doublet, although they are very lovely, bacd changes are a pain - and then ideally you need a lovely balanced ATU as WELL.. But coax is convenient and purched right, will last many years. PS - Have you checked the price of balanced feeder recently!?
For amateur use coax is the way to go, the losses are negligible for most of us to not even notice the loss difference. I wouldn't dare touch balanced, its a lot of work and not practical in all but ideal conditions. On the professional RF side my broadcast FM stations run a mix of 3" 4" or 5" coax over a run 1000-1300ft long (~300m) at about 20-45kw, I would be scared to put all that RF in open balanced feeder. My AM broadcast stations dont use balanced line and they came on the air in the 1940's - in a pinch I could use rg58 and only lose 1db over the 300ft run to the tower lol. balanced is great if conditions are absolutely perfect, but we are in a imperfect world and coax fits the bill, line losses are negligible when the right coax is used.
A few years back I walked into a discount store and there sat 1 big spool with 1000 meters of Times Microwave LMR-240 (Paid $89.99 CAD) solid core not flexi, but low loss. So sweet!
Wow
89 dollars...for the spool???
Thanks mate, nice video 👍
No problem 👍
As always TA2NC says, The "good antenna/good cable" is the cheapest "Power Amplifier". 73 DE TA2BOS
Very true!
Thank you. Merry Christmas and Happy New Year. N0QFT
Happy holidays!
The best coax is 1 and 5/8 inch hardline. Now, who wants to pay for it?
I got nearly 500 feet of double-shielded 75 Ohm CATV cable for free, and I can build impedance matching transformers for next to nothing. I've saved so much on coax that I can add a small power amp at the shack, and a receive preamp at the antenna to more than make up for any long-run coax loss.
Nice Video!
Thanks!
Balanced line is great if you're using a non-resonant antenna or one with an appropriate feed point impedance. I used to use a folded dipole for 40m, fed with 300R twin, but then of course I needed a 6:1 transformer before the tx.
However if using 50R antennas coax is better, especially if like me you don't want to use an ATU. The loss at HF isn't much if you use something half decent, RG213, LMR400 etc.
Yes Andy.. If you are a one-band-man, and can afford a nice big ATU then why not. FOr me, it would be difficult.
One thing that doesn't ever get mentioned and becomes more important the longer you go is noise.
Coax will pick up noise I've seen it tested, I believe this is due to leakage of the outer conductor, so buried coax will greatly reduce this.
But you can't burry coax the whole length.
The larger and better construction the less noise, heliax being the best as it has a single metal non braid solid conductor.
But heliax can still leak RF a little so underground burial is still the best.
If your noise floor comes up due to the coax you will loose signal to noise ratio.
Of course this is an issue on receive not on transmit, but transmit is only half the story.
Thanks.
Shane VK1NME.
Yes.. Leak is a concern (both ways)..
Interesting video 👍cheers
Thank you! Cheers!
Yes good coax is a must. Doing The connections correct will make it c worthwhile or turn it into a hot pile of garbage.
Great stuff Callum. Love your videos. I prefer Times Microwave but also sometimes ABR Industries cables are good. 73 W6DKW
OK, nice!
As a Foundation m7 I'm only allowed 10w; my rig has 5,15,25w outputs, and using the feed line loss to lower the RF to 10w, by the way I'm using RG8X on the 2m/70cm band! In some cases loss can be useful.
And your losses on receive..? Worth thinking about.
@@DXCommanderHQ I use RG 213 FOAM almost the same spec as LMR400 at 100 meter just something to thing about. I also use a max of 10 watts from my Icom IC251 and can talk over 40 miles, I even hear people others cannot.
Great video, loss calculations should be the starting point. You have to get as much power to the antenna feed point that you can live with, without having to donate a vital organ 😊.
Good point!
Great info Callum!
So my RG58 is no good for UHF @100w for a 150m run?😂👍🍻
Hahaha
Riddle me this. I have a field 50+ metres long and sloping south so the top is 4m higher than the bottom. My shack is at the bottom because it has a low voltage high current solar roof for running deep well pump and i had to minimise loss in that cable. Now i run a dipole from the shack on a 8m fishing pole on 10m rg174.
If i were to place the antenna at the top of the field i would gain height, but would feed it with around 50m rg11 because i have that. Will the extra height of the antenna gain more signal than the coax loses?
This makes me miss my 7/8" heliax
HI All ! Im have 27m rf 10 to switch , and switch antenna 30m rf7 . On 28mhz band im notice 20w loss. On 3,7 mhz 5w loss 😅
Suck outs out of band is a true problem that often goes unnoticed 😉
great info. I get asked coax all the time. my answer is a question. what frequency and how much power and how long. and what can you afford? I learned something about coax that is not in data sheet. the shielding foil aluminum . re doing a UHF repeater. 50 watt. was running LMR 400 coax . about 35 ft . all on roof of a office budling. rented space. outher stations at cite. was getting cross talk and inter mod noise at times into the repeater. was not too bad but a weak signal into repeater was a problem at times. even went with better duplexer . turned out to be the shield of LMR 400 was causing the trouble. with the RF from outher stations near buy was causing a reaction with diss similar metals in coax. That why you see hard line on repeater cites often. I made a switch to HYPERFLEX 10 Sahara FT8 from M & P and problem went away. was a GMRS repeater in the USA
FWIW LMR400 and similar are banned from many commercial radio sites, the dissimilar metals cause intermodulation issues.
I use LMR400 for everything at my station from HF up to 3 GHz. Been working great for over 20 years. I'm not in a multi-carrier high RF environment though.
@@stargazer7644 well said, it is the multi-carrier scenes where it can be an issue.
Can happen with EcoFlex too. The trick is to install it - and leave it (I think).
@@DXCommanderHQ if the shield gets damaged. I have it so not to flop around. problem was wrong coax from the start. all fixed now.
I have had good luck with Times LMR400 on 450MHz back in the states. Is this stuff available in the UK or EU? This was some 25 years ago in the States but now in the EU looking for recommendations on a low loss cable for 450MHz. Odd that I found connectors for their coax in my stores. Crimper has been in my tool box for years. The joys of proprietary goods. Max lengthen of run is less than 100 feet, yes I still work the imperial system, hard to teach an old ham new tricks!
It's available in the EU, but it's not all that competitive.
The issue is, that the regular amateur radio shops don't tend to carry it, so people need to go to professional electronics retailers such as Mouser or DigiKey or similar, and then figure out how to actually purchase the thing, figure out if they're buying single cable per meter length, or 1 m pieces, or 1 foot pieces, or a single roll with fixed length and then also find the appropriate connectors, and so on, and that takes experience, and some people are afraid of that.
For example, a 500 foot roll of LMR400 is 1115€ on German Mouser right now, plus tax gives me 1327€ for the roll.
On the other hand, the equivalent length of Messi and Paoloni Hyperflex 13 (which has lower loss than LRM400, but is ~13 mm diameter compared to ~10 mm for LRM400) would be around 1236€ with tax, and the SSB Electronic's Ecoflex 10+, which is also a bit better than LRM400 and has the same diameter, would be around 940€ with tax for equivalent length.
It's also a bit easier to find appropriate coax connectors on M&P and SSB Electronic's websites than it is to go in-depth and figure out what would be the appropriate part number for the LMR400, and then find that part on a website of a retailer.
So LMR is more expensive, has worse performance, and is more difficult to buy compared to local competitors.
See reply from Andre..
Very good reply Andre!
For me, the greater focus must be on the loss as it relates to received signal loss. In HF digital modes, how many contacts that worked sufficiently with a signal strength of -15db, won’t be viable at -17db? It think that it is a waste of time to dither over 1 extra db of coax loss.
Correct too!
Good comparison Callum. Next video - use ultra-cheap satellite TV coax and put up with it being 75 ohm and not 50 ohm. How lossy will that be?
Depends on how lossy.. Most TV coax isn't that bad. We should absolutely ban RG58 though!
The WRONG coax for ham radio is NO coax. The right coax is the one that gets you on the air.
I got one for you.... I have a 25 by 50 foot foot print for property. I have a 66' wire wrapped around the house with a 49:1 zep and about 75 foot fo RG8U coax. I also have a 1:1 choke on the antenna feed point. How can I improve on this if possible? I also have a Comet 250B about 40 feet at the base. Not really getting out on any band other than of course 40/20 meters.
OK, that's about 7m x 15m.. Well, I have to tell you, I would probably leave it as it is and drop a Signature 9 in the corner with some more coax and run 2 x antennas and maybe a switch. Now, a loop of wire all the way around is just over 40m so with some tinkering, instead of your 49:1, you could go a 4:1 and tune that on 40m, 20m, 15m and 10m. No ATU.. However, it's a bit of an oblong so not perfect. I would still run a DX Commander near one corner! LOL
I shall give that considerable thought sir.@@DXCommanderHQ
We've got an 'expert' on coax here in GI who thinks that you need to buy a pl259 radio end plug and a pl259 antenna end plug. Swapping them will destroy your rig 😂
Everyday is a school days when he is on the air.
There's a few!
Does he also believe the Earth is flat ?🤦
These coax losses are why I switched to balanced line. Way cheaper, too!!!
.. and your ATU?
@@DXCommanderHQ I use a Heathkit SA-2040 and an MFJ-969 (HF) and a MFJ-921 (2m), with 1:1 baluns. I feed the HF antennas with 450 ohm window line and the 2m antenna with 300 ohm twinlead. I am fortunate in that I live in a place where I don't have to try to keep the transmission lines hidden and tidy, so I can keep them away from metal siding and gutters and stuff.
I can't say that I am an antenna expert or anything, but it *seems* to work better than the cheapo coax that I was using before. But I may be full of manure, lol. And I don't know how it measures up against quality coax, because I am too much of a cheapskate to try that. ;3
I've always just used the insides of toilet paper rolls, wetted down with the lawn sprinkler. This would maybe explain why no one ever hears me eh?
So no-one has replied on air about your sh*t signal?
haha oh me too! They say "just get it wet, It will conduct!"
Add salt.
@@DXCommanderHQ That'll change everything. I'll have to redo my radiation safety study!
I am hearing many repeater owners using 75 ohm cable TV hardline as it is cheap.
When you did the M&P table at 2.0 you missed that was for 100M -- so 1.0 for 50M
I thought I added a little correction title at that point..? Oh well.
👋🏻Callum
Cellflex 1-5/8" 😆
Short feedlines with h chokes are your friends.
Putting cheap coax on your high performance rig is like putting remould tyres on a Ferrari! 😯
Why?
Coax, connectors and antennas are the means of transmitting TX power to the outside world, in the same way a car needs decent tyres to transmit it's power to the outside world. Skimp on these and your Ferrari drives like a Ford. 🤫
Tbh, I wish I would need 50 mtrs of coax to my pole and antenna in my back garden...
I use Rg-6 75 ohm stuff because I am poor.
I started off with RG6 and switched to RG213. I didn't notice any difference on the lower bands, the higher bands did seem to improve however. Use a half wavelength (34m if you want 80m) and the 75ohm thing isn't a problem :)
It's just bananas to me 🍌🍌🍌🍌🍌
So as a foundation license I can run 100w with cheap coax😂
Not sure.. On the "Full" it's at the feedpoint..
Me simple, me pick fat cable and it make more fars.
Easy answer, buy the most expensive (=best?) coax you can find……………….unless you can’t afford that. Then shop for the best alternative you can afford. It is what it is.
Best comment!
Funny how many hams have studios. Me too. M6NZP.
Ah cool!!!
Now days hams are trading in their coax cable for computer cable. No antenna needed. Isn't technology great?
That's called Skype, Zoom and Email.
Riddle me this. I have a field 50+ metres long and sloping south so the top is 4m higher than the bottom. My shack is at the bottom because it has a low voltage high current solar roof for running deep well pump and i had to minimise loss in that cable. Now i run a dipole from the shack on a 8m fishing pole on 10m rg174.
If i were to place the antenna at the top of the field i would gain height, but would feed it with around 50m rg11 because i have that. Will the extra height of the antenna gain more signal than the coax loses?
Riddle me this. I have a field 50+ metres long and sloping south so the top is 4m higher than the bottom. My shack is at the bottom because it has a low voltage high current solar roof for running deep well pump and i had to minimise loss in that cable. Now i run a dipole from the shack on a 8m fishing pole on 10m rg174.
If i were to place the antenna at the top of the field i would gain height, but would feed it with around 50m rg11 because i have that. Will the extra height of the antenna gain more signal than the coax loses?
OK, you just need to calculate the loss.. So for a 50m run, on 10m band for RG-11, that's about 2dB. OR you can upgrade the coax and gain about 1.5dB.
@@DXCommanderHQ i think having a higher antenna will outweigh 2db by a lot