I Bought KMR-400 Coax From Amazon | How Bad Can It Be?

Testing out the KMR-400 Coax Performance And Teardown.
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#hamradio #k8mrd #KMR-400

[@Gruuvin1]

A fair comparison would have been to run your same measurements against 75' of coiled LMR.

[@mewrongway]

Mike doesn't want to be fair! He wants to sell you on Chinese shit! I wouldn't put that coax on my DX Commander if you give it to me!

[@DXCommanderHQ]

This sort of stuff really suits you Mike.. Although I have to say, doesn't matter what you do, it's always just great!

[@hamradiotube]

Hey thanks buddy!

[@macgyver5108]

There's a "law" if you will about using calculators that applies here: "Garbage IN equals garbage out." Which I think you might have done right at the start by assuming the KMR has the same 84% VF as the LMR?! Messing around building 9 element collinear antennas out of coax from scratch I learned you REALLY need an accurate velocity factor measurement to get the lengths right for alllll those elements, performance and SWR can do wild things when you have 9 elements covering 4 bands and they all start interacting. Also learned an important fact about manufacturer's "VF numbers" vs post production reality... Not familiar how that Rig ex spurt stick works, but I unroll the coax and actually use a tape measure to get the precise length, a "known value". Then I hooked up my NanoVNA test leads and calibrate/zero those before testing the coax and doing some math on an ancient technology called 'paper'...😋 After testing a BUNCH of different batches of KMR-400 my samples all tested at about 4-6% faster VF than the 84% in print on the LMR data sheets. Over all I was pretty impressed with that coax and I'd say I got way more than I paid for.

[@johnjones2646]

#1: Never test cable, especially coax with a foam die electric in a tight coil. Read specifications of LMR-400 & look at installation criteria. That coil of ‘KMR’ was coiled from China waaay too tightly & most likely distorted the positioning of the center conductor in relation to the sheath. Bingo. There’s your excessive loss.

[@tangjinbh4fdj970]

which coax would you recommend？I am using ic705 with end fed antenna. Thanks!

[@KaL_Tero_Vet_RET]

I thought so too. I'm no expert but I thought it's gotta have some effect on its loss. I'm thinking about some 25' segments between antennas and rigs, and imagine the loss will be smaller than found! Thanks for your observation, John J!

[@germanjohn5626]

Add to that, that he did not really used the most scientific way of measuring this cable. A Simple NanoVNA would have shown him the exact loss and if there were some problems inside the cable because of dielectric distortion from the tight bend.

[@ajax1137]

@John Jones does it result in permanent damage or can it be corrected by straightening the cable out?

[@engineerncook6138]

Hmmm, I looked up the Times Microwave datasheet for LMR-400 solid core (not ultra flexible stranded core). It says: Bend Radius: installation in. (mm) 1.00 (25.4) Bend Radius: repeated in. (mm) 4.0 (101.6) If you can install LMR-400 with 1 in radius bends, seems to me you can ship it in a coil with a 2 in to 6 in radius bends. Am I missing something?

[@notreallydaedalus]

Thank you for testing and providing objective results!

[@Starphot]

Retired RF bench technician here. I worked for a couple of fellows in the late 1970's in a mobile stereo/ CB shop when the CB craze was going. We had problems with some of the customer's vehicle installs with the intermittent SWR readings. The cable installed was the off-the-shelf Radio Shack Tandy Wire RG-58. We then replace those with an Amp brand cable with no further problems. We dissected the Tandy cable and found at even intervals along its length there was the center conductor just pinching on one side of the foam dielectric to the outer braid, causing intermittent shorts. Tandy did produce their own wire and cable, I believe in a factory in Indiana. Evidently they didn't have enough cool time out of the extruder before coiling the cable up. Their coax products did improve though. Tandy did make their own xtals for their CB radios and scanners as well. These shifted lower in frequency over time sometimes into the next channel.

[@nicklikesradio]

🤣🤣

[@nicklikesradio]

As a current tech, ive seen some things... One of which is radio shack coax which at best had 60% shielding. Their molded connectors are garbage.

[@Silvertarian]

I was left scratching my head after watching this video. I went ahead and ordered a 75' run of kmr400. I tested it myself vs the old sma RG58 handheld extension cable I bought first 100' run(yes I'm dumb and learn the hard way) Both cables were ordered from Amazon. Here are the losses measured by my nano vna, and expected transmitted power from a 50w radio based on those measurements: Cable Type: KMR400 (N) 146 MHz: -1.09 dB (42.25 watts) 450 MHz: -2.29 dB (34.8 watts) Cable Type: RG58 (SMA) 146 MHz: -4.58 dB (27.8 watts) 447 MHz: -7.96 dB (14.84 watts)

[@jdschauss]

If you're on a budget, I still say wait and buy the good stuff. For 58 bucks and made in China, you can't expect it to perform as well as TM or M&P. You want good coax, you will have to shell out the green stamps for it. Great video, Mike. -K5SFC

[@wordwalker3]

Excellent video! I have an 80 foot run from my entry panel to a tall oak tree. I used M & P hyperflex 13 with N connectors for the 2 meter/70 CM run and DX Engineering DX 400 Max for the three other runs of coax. Two are covering UHF/VHF and HF, leaving two DX 400 Max runs available for expansion. I have lightning arrestors both at the base of the tree and at the entry panel with both bonded together with appropriate ground wire and ground rods(including the service ground). I spent the most $ where I would have had the highest loss (VHF/UHF). I felt that the DX 400 Max was close enough to LMR 400 and that the cost savings justified it (bought a 500 foot bulk roll). The run was underground in a plastic electrical conduit. Downhill from the tree to the house with drain holes in the conduit just before the 90 degree bend up to the entry panel as an egress point for any water that might get into the conduit. I used the M&P Evo connectors...see Callum's video. The soil here is red North Carolina clay...I didn't want to dig a trench more than once!!! I had to wait for the budget to catch up to the purchase order and I am glad that I did. Perhaps there was a reason the KMR specs were unavailable! I'm generally of the opinion that over-engineering is under rated! Though I did have budgetary constraints to contend with1 73

[@DonzLockz]

All things considered, id keep it as a backup feedline. Great test Mike!

[@daveN2MXX]

Great video, thank you! "Better" is subjective, and this coax is likely "good enough" for most amateur radio use cases. It seems great for the price. But I'm using 75-ohm RG6 for my HF antennas, so there's also that.

[@samallan6616]

I got some free reel 'tailings' of RG-11 years ago from an apartment construction project installing cable TV trunks. Ended up with several hundred feet. You can spin '259's onto it easily. I use it on everything except my dual-band antenna. Great stuff. SWR is acceptable. 75-ohm cable was in use long before 50-ohm stuff was around.

[@gfodale]

Back in the 80's, I used RG 8 and RG 58 from Belden. Both in the Marine Corps, and personal use. Currently, for HF, I'm still happy with standard RG 8, RG 8X, and RG 58. For VHF and UHF however, I tend more to LMR 400, where the lower loss in those bands are substantial. I'm on a small fixed budget. I terminate my own cables and buy bulk cable as possible. Tailor the cost to the application is my thought. Nothing is perfect. We do what we can. Also, as a side note, your coil looks like a loose choke from other videos. Others have commented, so I won't belabor the point. For those unknowing, please seek the other comments and search for common mode chokes. I've not done my own tests as yet, so I won't comment further. (tests are planned, just not today.... :) )

[@ronwolenski-n8wcr]

I think if you are on a tight budget that is a good deal. Of course if you can afford it you would go with the M&P.The connectors look great, I cringed when you cut that one off.

[@DrumCoversbyBill]

Thanks for sharing. I just received a 25 foot roll of this for my VHF/UHF base antenna (From the antenna to lightning arrestor at base of pole) Looking forward to see how it holds up.

[@W9HJBill]

For the price, it looks good. A lot better than RG8. 😁

[@marlomontanaro3233]

Probably suitable for most installations but a few thoughts... Lack of specs on Amazon mean you had to assume a lot in your testing. It is possible it performed even better to its actual specs, just not to LMR-400's specs. (Although, who knows... without the specs, it may have performed even worse!!) But since no one ever claimed it was LMR-400, is it fair to test to that standard? Probably not. You should have done an actual length measurement- simple enough to do accurately. Chances are, it really was 75-feet, just that your velocity factor was incorrect for the actual sample of cable you had and therefore the length measurement is off a bit (also, TDR length measurements are rarely accurate). Having said all that, we don't really know what the dielectric used is in this cable. That has a huge impact on the test results. The other "Amazon" factor is that you could order this cable ten times from Amazon and not get the same exact product each time. So who knows what you're getting next time or from where? Will those good connectors be on each product? Don't know. When it comes to the performance of radio systems, the transmission line is absolutely critical. Especially when tower climbing and winter maintenance come into play. Better to spend a little more money and get known quality cable from known reputable distributors who know and understand what they are selling. Amazon's integrity goes as far as refunds or replacement - but that is little consolation if you missed grabbing rare DX because of a cable failure at the wrong moment. As always with the likes of Amazon, eBay, etc., buyer beware and you get what you pay for.

[@4X1000]

Agree fully on every single word! Living 70 km south of the Arctic Circle and with the temperature (-27) at the time of writing, there is no doubt that a good brand coax is the way to go! I would not call it a healthy operation to climb a tower today. 😁

[@nicklikesradio]

Thats a nice induction coil you're testing.

[@AlanElBee]

Great video, Mike - happy to see an honest review on something I use that might save me some $$. 73, K7KS

[@JoeFramo-uw9fp]

Thank you Mike very good video😊

[@donalddodson7365]

Thanks. Interesting review.

[@Andrew-yx7sf]

I bought a 50' piece of this for a 10meter dipole. Seems like decent quality and I am having good results.

[@jackK5FIT]

Been down the cheap coax route before and decided to do more research and testing and now I run Times Microwave LMR-400 on both my homebrew EFHW and DX Commander Classic. I haven't regretted that decision at all. I recently got on the M&P bandwagon and bought a 50ft run of Ultraflex 7 and an 18ft run of Ultraflex 5 for various portable setups. I haven't tested the M&P coax but I trust the KZbin guru's findings. Some cheap coax may be good but I will stick with brands I trust. Thanks for another great video.

[@mikebavoso26]

Very interesting test, thank you. I'm going tbe in ham for over 50 years and this is the first time that there are so many vendors building coax. This would be an interesting video series for you to continue with the other manufacturers such as, but not only including DX engineering, who build their own coax cable. There are a lot of vendors on the Internet advertising LMR 400 coax made by other than Times Microwave, these would be interesting to examine.

[@josephtotter7484]

46 and some change for me :)

[@germanjohn5626]

Anyone can make coax in their garage and can call it whatever they want.Ordinary coax cable is not regulated and buying 3rd party cables can get you anything from great to utter junk even from the same part number and vendor.I always laugh at the average ham, they don't think twice at spending a couple thousand dollars on the newest rig and then skimp on the most important part, the feedline, buying and using the cheapest junk they find.

[@josephtotter7484]

@@germanjohn5626 so are you not an average ham:)

[@thomasbjarnelof2143]

I bought somting like that that, and it was copper clade steal as inner conductor. A couple of years and the inner conductor corroded away from the outside connector. Indoor was not corroded.

[@davidsradioroom9678]

It is better than I would have expected, as well. I think it would be suitable for most installations.

[@g0fvt]

A test you might consider is to seal the ends of a few 1ft long samples of various cables and see how they survive the sunlight, I am in the UK so the test might take forever though...

[@jdschauss]

Nonsense. You folks get AT LEAST three days of sunlight EVERY YEAR! 😉🤣🤣🤣 -K5SFC

[@johnkaelberer237]

Thanks for showing this Mike. In my use, coax is something that stays in service for a good period of time. It's worth it to me to get a coax that I know to be top quality. Pay now or pay later. It would always bother me that I was leaving some signal on the table. If your strapped for cash, no doubt it would be better than RG-8X. I have Chi-Com radios and radios made in Japan. The Chi-Com radios are my throw away radios for the most part. The radios from Japan are the ones I'd bet my life on. I'll stick with M&P or Times Microwave. You're still Killing it Mike !

[@williambarrett70]

Thank you, Mike. 73. WW5MB

[@Chris_at_Home]

As someone who worked in telecommunications we would never use some off brand coax. I worked with frequencies from high band VHF up to 13GHz and failure of communications causing a pipeline shutdown could cost millions

[@tonyd6884]

Good video great info.

[@Aimsport-video]

Like you said… not bad for the price… great video. Thank you.

[@SouthEasternCommunications]

Looks like a good budget cable for hf .. looks very much like a ll400 I sell here in Australia 🇦🇺 Good video

[@ko4otv43]

I bought some this for my ocf dipole. I was skeptical at first but It works great.

[@michaelzimmerman9221]

Been using for 3 months, much better than most, for the price range!

[@GreggK6EGG]

great video!

[@kimowen7189]

Hey Mike, love your videos! Have you considered using a nanoVNA and making a 2 port measurement of loss from 160m, up into the uhf range?

[@myradiovideos]

Good Point.. My guess is that the added loss at the higher frequency is related to the dielectric material used.. Also is how close the tolerance is related to the center conductor and shield. Is it perfectly spaced along the entire length. I had a VIP tour of the Belden Factory back in 2012, and the machines used to make their cable are super complex and fully computer controlled. Who knows what they do in China??? Robert WA6PHN

[@hamradiotube]

I have not. I actually bought a Nano VNA a couple years ago and hated it so much I gave it away. Too clumsy of an interface.

[@bobdole57]

​@@hamradiotube for the price it's an incredibly powerful tool.

[@timbookedtwo2375]

If your coax lengths are to very long, it doesn't really matter. Mine are all less than 50feet (30m). I have an eclectic collection of coax and don't notice any significant differences among the types of and brands of coax I use. If your coax runs are 100, 200 or 300ft long, well, take out a second mortgage on your house and buy some "quality" cable.

[@randykitchleburger2780]

When you get to UHF regular RG58 starts becoming very lossy. 7db at 50 ft.

[@timbookedtwo2375]

@@randykitchleburger2780 I use RG213 or some heavier gauge coax for my UHF/VHF feed lines. For HF RG58 is cheap and works ok. Like I mentioned, my feed lines are less than 50ft, some much less, especially in portable/mobile situations.

[@NVBL42]

@k8mrd I’m curious if you put a solder connector on if it would recoup some of the losses.

[@hamradiotube]

The connector actually was soldered as well as crimped.

[@Soladaddy]

I love cheap so much I bought some RG-213 with a MFJ label for a really good price. Two years later the jacket that was exposed to the elements was in terrible shape. By comparison it was installed near some Wireman RG-213 that was installed 20 years ago and the Wireman outer jacket was in much better shape.

[@IZ0MTW]

Nice that you analyzed that cable for everyone. By the way db is a logarithmic scale, not linear, so you cannot say 3db loss equals 50w so 1db every 16.6 If you expect 0.6db/75ft of attenuation at 50MHz the power you should expect is 87.1 Also in all of these measurements you should take account of the power meter accuracy and the stability of the power source (ie the radio). But I guess at the end of the day, to have a rough idea what you’ve done is enough. 73 Diego

[@radiojared]

Came here to say this, glad someone already caught it.

[@johnjones2646]

Also, foam die electric coax in an excessively tight coil by default created attenuation, thanks to distortion of the foam. LMR was designed for straight runs with sweeping bend radius (can’t recollect specifics)

[@Rob2]

Calculating cable loss as "percent efficient" and reasoning "50W is 3dB so 1dB is 16.6W" - I'd say he is not qualified to review coax cable.

[@germanjohn5626]

@@Rob2 Well, that is what you get if someone makes You tube videos without understanding the fundamentals he / she is talking about. There are a lot of those self styled experts on you tube and sadly those that really know their stuff are few and far in between.

[@ELVISRN1]

@@germanjohn5626 ok great...wheres your vid?

[@johnkubik8559]

if you want to measure a cable specifications you need to lay it straight, a roll of cable has completely different characteristics.

[@electronicsworkbench]

I was kinda thinking the same thing. You make a choke out of coiled coax to change the characteristics of the cable's operating parameters at that point. I'm not sure testing the 75ft coil is very telling. How about a follow up with the cable rolled out for comparison?

[@hamradiotube]

A choke is to prevent RF from coming back on the shield. I'm testing power into a 50 ohm dummy load. This is not my first experiment and in my experiments I have found that for power testing, it makes zero difference. Look at my videos testing Messi & Paoloni Cables. They are all uncoiled. Before I uncoiled hundreds of feet of coax in my house, I took a power reading. After I uncoiled them, I took a reading again. Would you believe they were the exact same number?

[@nasanction]

I ordered RG213 with pl259 couplers from Amazon. I had to replace all the fittings as they were pressure fitted on the braided side with no holes to put solder, and didn't make good contact. After replacing the fittings, and soldering everything, it performed as I expected.

[@nicklikesradio]

2:40 coax with gain?! Wow 😍 😂

[@125brat]

We used to refer to it as "Gainiax" 😂😂

[@ae1tpa92gwtom2]

58$/75ft, what a bargain , happy holidays Mike , 73

[@moss-ccw7971]

I'm not trying to be critical, but you should have adjusted the VF to match the length, instead of assuming the cable was shorter than 75 ft. You could have ran it with both VFs and then uncoiled and verified the length after you were finished. That said, thanks for all your work.

[@snokones]

Worth it

[@lyfandeth]

And of course there is no way to tell if it will get brittle, or ooze plasticizers, or the dialectric breaks down over time. Good enough for "we'd better grab some extra cable" field ops, where sometimes the cable WILL have doors closed on it, etc. But I'd prefer something I could rely on, not whatever the shipper sent in a random week.

[@thomaswellcome5663]

Hey I'm looking for a good quality jumper to run between my amplifier and my cb radio. Any ideas? Looking for something pliable

[@TallTexasGMan]

It would be interesting to do a true comparison of diameter, coverage, and true performance. I also believe that for the test to be accurate, the cable needs to be stretched, suspended in a non-conductive tray and measured. It would be very interesting to do an LMR-400 vs the KMR-400 and other brands. Do all of them at 100 feet since that is how the standard is made, but some companies probably do their measurements in meters. Also, I knew the ad was suspicious on Amazon as it said cable is made in the USA and assembled in China. LOL!

[@hamradiotube]

Cable 100% does not need to be stretched out to test for length, loss, velocity factor, etc. It is just fine coiled up like this. Trust me. I just spent 4 days in Italy at the Messi & Paoloni factory. I have a video that will be coming out in the following weeks showing how they test their coax so you can see how it's done.

[@jetcyclezero8907]

Thanks for the thorough demo with test gear.I am now much more confident.I am using this Mookeerf KMR400with 500+- watts SSB and I was cuirous what the compression pl259's pin was crimped and soldered.The pin looks larger than I thought.I bought Some Alpha 75 ft rg8 that had Aphenol cntrs so I figured the coax was good,NOT! .The coax was sparse weave aluminum shld which did not even last a year and corroded and burned.

[@ralphmowery2898]

I never did think it was a good idea to use compression connectors on solid wire, especially the aluminum coated copper. They are fine on stranded center wire.

[@buzzsah]

The connectors may have a problem tightening up on the radio/antenna. I bought 25 that looked like them, the threads on the sleeve were not enough, causing only 1, maybe 2 turns on units

[@robertsumption1243]

Buzz I ran into that too and got on Ebay and bought some Amphenol pl259 connectors and soldered them on ...problem solved 73 Bob

[@robertsumption1243]

FYI my cable had copper braid

[@buzzsah]

@@robertsumption1243 I bought the bad units from HRO, I called the day they came in. I was told to send a pic, I did, never heard from them. I spent over $12.000 that year with them. You would think they would replace them. I no longer buy from them.

[@radiotests]

put it out in the texas sun and see how it weathers, plus do some real contacts to see if its ok. 58 bucks ? Id bite.

[@ke4edd]

First time seeing shears like those used at 6:47. I like those. Bet they beat the crap out of using a knife for the same purpose.

[@davidc5027]

Was the cable tested all rolled up? I would use it for shorter runs, but probably not longer.

[@HamRadioCrashCourse]

Let’s go!!!!!

[@N9XY]

I get a chuckle when people talk about brands like Messi and Paoloni. Like it’s something akin to Rolex or Ferrari. I have my ham fest spools of Tandy RG 58 etc. there are other parts of the system that have a greater effect on the station. Most importantly are you having fun making some contacts within your budget?

[@VernonBlack2]

So it's good stuff! That's good to know. I'd been more impressed if he had compared the same length of LMR 400 with connectors hooked up in the same way and showed those results instead of just relying on the chart of specs for the LMR 400! On the one hand he doubts the specs of KMR 400 yet believes totally the spec sheet of the LMR 400!!! It's been my experience those specs sheets from manufacturers are always calculations from IDEAL LAB CONDITIONS and i doubt anyone can duplicate those findings in the field! So like that guy im actually impressed with it! My only complaint is I don't like the big thick coax. It's just too hard to handle. Thanks for sharing!.

[@dmc31405]

How does Alpha Coax stack up? I’m thinking about buying 50’ of RG8U or some RG8X from them.

[@B.Murphy]

I bought all my Wilson-400 open box "used" on amazon! About 150ft for I think around $60. I believe that was a lucky draw though.

[@davidlewis1221]

Good deal if it will stand up to UV rays. Here in Texas,I've seen cheaper coax get brittle and crack open after a year in the sunshine.

[@TheOpticalFreak]

Is this 50 or 75 ohm cable?

[@jerryinman1360]

I bought some of this cable and the threads where missing so I sent it back. I ended up going to Ham Radio Outlet for my cable. Got way better stuff. KD6VGB Jerry

[@joeb3300]

To agree with some other comments: (1) I would have uncoiled the cable and measured the length rather than assumed that the VF was known. (2) I would not measure the properties of the cable while coiled. (3) A nanovna could have given you losses across the bands in one measurement and probably made the task easier, but I see no flaw in your approach other than those just stated. And I agree that for a non-flex cable, it came from the factory too tightly wound. The center conductor has probably "taken a set" off-center permanently altering the electrical properties of the cable. Thanks for your video and support of amateur radio!

[@hamradiotube]

Measuring a cable while coiled has no effect what so ever.

[@ubergeek318]

Thats not a bad cable to have as a back up or for a cheap uhf vhf setup. Looks like imma have to find some to play with

[@CoveiraoPS3]

Ah… trying to make the competition of his sponsor look bad. Good business!

[@hamradiotube]

What kind of stupid comment is this? And who is my sponsor? You are totally clueless.

[@GroundControl204]

RG 400 is the way to go, especially concerning its high heat tolerance makes easier for soldering connectors.

[@jimeppright7862]

Not for longer runs - look at the loss. 4.4 dB/100' at 100 mHz. compared to 1.232 dB for LMR400. Soldering a foam dielectric coax works fine. You just have to tin the braid with a large iron before installing the connector and after installing the connector, let it cool before moving it to allow the foam to re-solidify. Quality crimp-on connectors work very well.

[@GroundControl204]

@@jimeppright7862 That loss is at 100 feet though. I have my antenna mounted at 36 feet high which is the first wavelength above ground and the loss at that length is near zero. Also, majority of base stations don’t have antennas nowhere near 100 feet and that’s a factor. So inevitably, as time progresses and the weather and sunlight has damaged the LMR outer jacket “especially that junk ultra flex outer jacket” the RG 400 will still be intact. I ran times microwave LMR 240 and 400 for decades and neither type made it passed 6-7 years without the outer jacket ruined by sunlight and weather elements. Since I’ve upgraded to RG400 12 years ago, coax maintenance or replacement is not needed. Beside, I’ve seen BBi run 30,000 peak watts through RG400 and we all know you can’t even do that with anything named LMR. 73☑️✌🏻

[@jimeppright7862]

@@GroundControl204 Replacing coax after 6-7 years is a sign of poor quality coax or a wrong choice for the installation. I've had many hundreds of feet of CommScope LMR400 outside in a southern state for 16 years so far and it is fine. I have not used LMR400UF because of its well-known premature jacket deterioration. Belden makes a durable version, the new, not the original flawed, 9914 as I recall. I had some of it up as a rotator loop for 10 years with no sign of deterioration. I would not use RG400 in a rotator loop because of its stiffness. I am interested in weak signal work. So, to me, almost zero loss means much less than 1 dB. If your coax is 50' long and used at 28 mHz, the loss is just over 1 dB. LMR400 would have about .32 dB loss. I'll buy all the .7 dB I can get for $100 each, and 50' of LMR400 with connectors installed is less than $100. That is better performance than RG400 for much lower new cost. I have used short pieces of RG400 for jumpers because I got them surplus for peanuts. I would also use it for toroidal chokes. But I would not use it for a lengthy run no matter how cheap it was. As to power handling capability, RG400 is spec'ed at 2.75 kW at 30 MHz. You can calculate how much heat it would have to dissipate at 30 kW. I think the dielectric would not arc over (although the connector probably would), but the center conductor would be red hot really fast. Don't have certain animals around, small amounts of evaporating PTFE is poisonous to some.

[@LifeAtTerminalVelocity]

Great testing as always Mike!

[@hamradiotube]

Thanks Carlos.

[@bobofthedeep]

are results like this linear ie can you adjust the numbers from the other coaxies to equalize the length?

[@hamradiotube]

I'm prob not smart enough to know that but in other tests I've done with different lengths, I've just looked at the overall loss compared to what the manufacturer specs according to the specific length and frequency. Because I don't have all the same lengths of coax and don't really feel like cutting them all to the same length I've found that gives me a good enough comparison between them. You can see what I mean in this video I did testing M&P coax. kzbin.info/www/bejne/e5PVqnSFg8dkeLM

[@MentalWhiplash]

Definitely living up to what it costs

[@RedeyeParker]

Give your recommendation for cable and lengths Jumpers etc

[@nealbeach4947]

WoW! Pizzed off a bunch of the experts that actually bought this Chi-Com knock off.

[@KeepEvery1Guessing]

When the lawn guy runs over it with the rototiller, which cable would you prefer that it be. (Me, I don't have a lawn guy.)

[@digitaldreamer5481]

Aloha Mikey, here in Hawaii in which we have three volcanoes erupting all at once but only two putting out tons of VOG, which almost like Fog except there is Sulfur Dioxide, Sulfuric Acid and Glass within the gases of VOG. Meaning that if you use cheaper coax like RG of anything, that metal braid is going to turn a brownish purple powder within a year. This also means that you are going to spend 4-5 times the money vs using LMR 400 to begin with, plus all the labor involved. Simply not worth buying the cheap of anything is a waste of both, time and money! Sometime those connectors have a gap or hole at the tip, which I will fill it in with a nice healthy drop of solder and call it a done day! What I’m looking for is a complete airtight seal. Period! However, with the price, cost of shipping to Hawaii and the kind of connectors, I think this coax would still be worth the money spent! 🇺🇸🇺🇸🇺🇸

[@ChristiannTyler]

There’s coax that’s become pretty popular on Amazon it’s knock off rg400 people are claiming it’s identical and I believe it’s about 2 bucks a foot. That would be an interesting video!

[@rickpinelli1586]

Considering the price of HF radios and quality HF antennae, why would you want to skimp on the coax? Coax is the weakest link in your communications system subject to all kinds of environmental hazards, pollutants and toxins. I pay the extra dollars and get the good stuff.

[@greenyonline]

👏👏👏👏👏👏👏good for you

[@ELVISRN1]

great vid,all hams and cb folks ,ask yourself ???if your a race car driver......do you run the best fuel??? or regular???fuel??do it right . great vid

[@etxfire]

What if you put good M&P connectors back on it instead of the crimp type? Then try the tests again? Maybe unroll it just to keep things straight (ha ha!)? Thanks for all you do for all of us!! Thanks - Curtis - N5BIG

[@jakebrodskype]

I really wonder about how tightly that cable was rolled up. If you carefully unrolled and attempted to straighten it out, would it still read as badly?

[@franksilvia3402]

Exactly it’s creating a rf choke.

[@yakovdavidovich7943]

So... normalizing your results on db/100' and comparing KMR-400 to LMR-400, I'm seeing that it averages less than -0.2dB loss compared to the LMR-400 (worst at -0.39dB at 15m; strange shape to the data suggests measurement error, IMO)? Not sure what the accuracy would be on the MFJ-849. Would have liked to see the testing methodology (mode, sequence, timing, temperature, etc.). Percentages murk the water; should have done apples to apples with the cables and measured in dB.

[@jasonconrad9212]

Would soldering the Center conductor make much of a difference?

[@g0fvt]

Professionals prefer crimping these days. A well done crimp produces a cold weld.

[@bigchew3149]

i have never had any luck out of junk cable/coax it gives me fits every time i cheep out it bites me in the well you know...tried it again last week and same results & i knew better and still did it so NO CCA EVER Its nothing but junk (to me) copper is King & Really the only way to go IMO ! I have ben into radios for 30-35 years an even run a repair shop for 20+ years ! This ij just my experiences with it an like always yours may vary !

[@M9A1MAN]

We need some K8MRD-400 coax. I'd buy 100 feet!

[@MT_Madman]

Most testing is done with a straight cable not coiled up, did you do your test with the cable still coiled?

[@hamradiotube]

I have done both and have found that it doesn't matter.

[@edppdsc]

I am replacing my coaxial cable with m & p. What's the difference in benefits between the larger diameter to the smaller diameter coaxial cable.

[@hamradiotube]

The larger the diameter of the coax, the more efficient it's going to be. You can use their coax builder to compare coax in terms of length, size, and efficiency (attenuation, the less the better). messi.it/dati/layout/attivo/calc_ord.asp?l=EN&

[@edppdsc]

Thanks

[@arlenewolf5260]

Is the Mesi and Paloni better than LMR400?? Also what do you think about Andrews Heliax LDF-4?? or LDF-6?

[@hamradiotube]

Yes it is. Haven't played with any Heliax though. That's some serious stuff.

[@ml.2770]

Super Good Enough

[@TheArtofEngineering]

Do losses shown online factor in connectors?

[@hamradiotube]

They factor nothing but what you see in the video. Like I say, there is zero info from the manufacturer. Take this video for what it is. A power test.

[@vk3zen-rfdesign980]

i think you might find the VF is off...the 84 VF is for braided centre not solid...according to nanovna ...my cable measured around 88%

[@jpipod1]

Man, you had an RF chock testing in a coil like that.

[@hamradiotube]

not at all.

[@nvrumi]

Thanks for the interesting video. It's a decent test, but like another said I would prefer to measure the velocity factor instead of using the published value for Times LMR-400. I would also recommend computing the loss in dB for comparison with the table published on the Amazon site and for comparison with other cables. It would be easy to normalize the result to loss/100ft or whatever standard you want to use. I wonder if the capacitance of the dielectric could be (easily) measured... that would provide another data point. All that said, I have some cheap cable that I bought when I first became a ham (about four-years ago). But now I buy cable from reputable sources, including direct order from ABR or buying from DX Engineering. I really don't trust Amazon and do not want Chinese sourced supplies. The Chinese *can* make good stuff. When they do, the cost is comparable to other sources (naturally). I'm reminded that when I was a kid (the hills were not yet dusty), "Made in Japan" was a pejorative. The Japanese figured it out and now their production quality is top shelf. The Chinese can too. 73 de AG7TX

[@timbookedtwo2375]

Long ago the British had products coming from Germany labeled as "made in Germany," also to reflect alleged poor quality. Of course now "Made in Germany" is a badge of quality with (almost) no equal.

[@germanjohn5626]

The Chinese already have figured it out, whatever you buy cheap are mostly small garage cottage industries...that is where most the junk comes from, that and contract manufacturing purposefully designed and produced to be cheap... there is a whole industry in China that does contract manufacturing, from boards to solder. depends on what you want for the gadget you are selling you can have quality machine placed automatic soldered boards, you can have quality control brand name parts or rejects / fakes , you can have your boards soldered in the homes of people who get paid by how many they can do in a day.The latter has no quality control. All this ends up being sold to the cheap hobbyists and hams mainly in the US and Europe and Australia. The big manufacturers offer and deliver quality work with quality parts that can hold their own with anyone else in this world.

[@stevecorrao7170]

How about the Bolton 400? Could really use your expertise and opinion! Please! Thank you!

[@tomstrum6259]

Maybe you can reterminate the coax with traditional Amphenol solder type PL259 connectors & Uncoil the coax for retesting the dB loss...Your dB loss/frequency measurements seem way higher compared to its quality appearing construction....

[@2EOGIY]

I wonder if you would solder connectors will it help with power loss?

[@nicklikesradio]

If the crimps are done properly, not really. If the crimps are loose, definitely!

[@johnyoung1128]

@@nicklikesradio It’s interesting to note that crimp connectors are used near exclusively in air transport aircraft, an application that demands reliability so that shows that if done properly they are not a problem. Soldering a copper clad aluminium centre with a foam dialectic can be difficult due to heat transfer down the conductor and melting the dielectric. Solder can be botched too.

[@guykovacs9334]

Lets see you test the higher bands 2M, 1.25M, 70CM, 33CM. Not every technician can aford a LF radio and its agaist the gods to use a homodyne radio. Some would think it crazy but i use a 12vdc 4 antenna switch on the mast and a 3 way inside to change radios even got my gmrs antenna on it aswell. Curious??

[@K1RKK]

Sweet Content As Usual! The little music track you overlaid in the background had me pulling off my headphones and looking around…is that on the video😂🤦🏼‍♂️😵‍💫 I’d ditch it or turn it up 🤣🤣🤣Y’all Mash those “LSB” buttons and Like-Subscribe-Bell notifications! Keep it up Mike 73 de K1RKK

[@jimkranda1950]

Mike. Have you checked the outside cover on the coax? I have found that a lot of foreign cable has a soy based cover which critters like to chew on.

[@ELVISRN1]

great point,like my 81 corvette dash wires.

[@wx0mik]

I think it depends on what you are doing. In most cases you likely won't notice as a casual operator.

[@jordanch68]

I'd be interested to see the results of that cable with a soldered on connector, perhaps one of better quality.

[@johnyoung1128]

I doubt it would make a measurable difference.

[@45auto]

Interesting. The build looks like pretty good quality. I'm curious as to what causes the greater signal loss.

[@johnkaelberer237]

I'm thinking the signal loss has to do with the quality control as to keeping the center conductor as perfectly centered in the coax as possible. Materials could be another issue. You saw just how easily Mike was able to rip the outer plastic off the cable. Not so easy with the quality stuff. Of course Mike is a beast, maybe he just made it look easy...lol

[@DagonNaxos]

As the other person mentioned, the gap distance in the foam air core. But also the crimp connectors and resulting interfaces. I'd be willing to bet with a good set of press or solder type PLs for LMR from TMW or Belden etc would probably improve performance

[@ralphmowery2898]

The greatest loss in coax up to around 1 GHz is the copper loss , or should say conductor loss as some of the cable id made up of other materials than copper. That is called the I square R loss, or the heating of the wire loss. Standard power loss in a conductor of any type including the house wiring or wires going from the DC supply to the radio. The foam type insulation just allows larger center conductors for less loss for the same basic size coax. There is some small less loss in a solid center conductor than the stranded especially as the frequency goes up.

[@glennarrant3743]

I wanted jump in on the solder verses crimped connectors conversation with a slightly different view…maybe. In aerospace the decision to crimp or solder was based to several factors. 1. Was the instrument that was being specified “mission critical”? 2. How much power was the cable carrying? 3. Was it possible that the instrument being installed have to be removed for service or maintenance? 4. Was vibration a consideration in the choice? There were several more items but they do not apply to the HAM applications. The decision that everyone has to make is the connection mission critical? Does mission mean you have to solder? No. In general crimping was used on multi pin cannon connectors were vibration was less of an issue because of the strain relief that was in place. This is where you get to decide is the connection mission critical, and do what you think is best. Glenn N6JAI

[@clownworld7763]

I would be interested to see how the cable does at higher frequencies. Being that the cable is copper clad aluminum, my guess is the performance would be better where the skin effect is more prevalent.