Cable types and losses

[JohnE]

been meaning to put this out there for a while,since I have had a few conversations about this w/various members.
first pics,cables from L-R w/associated N male connectors.
RG8/213 LMR400 type, 1/2Inch superflex, 1/2inch hard line also known as Heliax, 7/8inch hard line.

 

 
[ MyGMRS STAFF EDIT:  3 Photos no longer available from linked source.]
 

 

now lets talk about the losses in Db and how much power that is.
Cable type                                  loss at 100Mc                          400Mc


RG8/213                                      2.0dB/100'                              4.7dB/100'
LMR400                                       1.2                                         2.5

Hardline type                                       150Mc                              450Mc

1/2" superflex                                    1.3dB/100'                         2.3dB/100'
LMR600                                             1.0                                   1.7
1/2" Heliax                                         0.85                                  1.5
7/8" Heliax                                         0.44                                  0.8
1-1/4" Heliax                                      0.3                                    0.6

dB loss            power loss in %
0.5                        10                        100W in 90W out
1.0                        20
1.5                        30
2.0                        37
2.5                        44
3.0                        50
3.5                        56
4.0                        60

all of the above loss specs are manufacture specs, I strongly suggest that you measure your line loss w/watt meter if possible to know exactly what you are getting at the antenna.
IME most of the book specs are on the money for hard line ,RG8/213 can be a crap shoot depending on manufacturer. I've had some really bad and some pretty good.
LMR I've had a love/hate relationship w/, good cable but seems to be prone to moisture issues. wish I had pic of the 7yr old cable that pretty much self destructed.
hope this is of some help to those looking to put up a machine or control station in the future.
JE

***EDIT***

found this very useful

http://www.arrg.us/pages/Loss-Calc.htm

Edited March 12, 2022 by JohnE

[Newb]

I have found the following website very helpful in determining transmission cable quality as opposed to the cost of the unit you need from the antenna to the radio.  It also lists flexability specs for the different low loss cables.   https://www.timesmicrowave.com/Products

They also list specs on connectors.

[Lscott]

On 7/27/2022 at 12:55 PM, marcspaz said:

I think there may be some misconceptions about UHF connectors (and M-type) vs N-type connectors when it comes to the bottom end of UHF.  You can buy garbage UHF connectors that won't work well, 100%, but that holds true for N-type, too. 

 

N-type connectors were created in the 40's, when there were no real standards for UHF connectors, not that there is much of a standard now.  The DOD needed consistent performance, so Bell Labs created a standard to be met and created N-type connectors.

 

If you buy a quality silver/teflon UHF connector manufactured by a company like Lands Precision or Larsen (about $8 per connector, $16 per set to make a cable) you will not see any difference in insertion loss or any performance degradation when compared to a comparable price and quality N-type connector in GMRS systems.  I personally have done tests using LMR400.  I made 2 patch cables that had UHF connectors and 2 patch cables that had N connectors.  I tested them with my analyzer between 440 MHz and 500 MHz and there was exactly zero difference between 3 of the 4 cables.  One of the cables with UHF connectors had an increase in insertion loss 0.01 dB... which I am assuming had something to do with me and the way I made the patch cable or possibly the section of cable itself introduced the difference and it had nothing to do with the connectors.

 

Bottom line, we are not running enough power, moving enough data, or have high enough duty cycle that would require an N-type connector.  Our only real benefit would be for outdoor connections and utilizing the native weatherproofing instead of having to add additional weatherproofing to a UHF connection.

Insertion losses are not the only thing to be concerned with. Did you do a reflection test on those cables? The connectors might be low loss but still cause issues with a crummy match due to the non 50 ohm impedance they have.

At one time I looked at the effect of using the commonly seen barrel connectors. People use these for feed through in walls, doors and patching shorter lengths of coax together. This was just a "theoretical" exorcise to see what one might get in practice.  

UHF Connectors Rev-3.pdf

RFU-537.pdf

[marcspaz]

1 hour ago, Lscott said:

Insertion losses are not the only thing to be concerned with. Did you do a reflection test on those cables?

 

Not until just now. LOL  Seriously, when I made the cables, I looked and didn't see anything horrible. 

I still use all of the cables.  So, I dropped two of them from the gear for a few minutes and put them on the analyzer.  The complete cables are almost identical.  The values are so close and near where they should be, that for what we do in GMRS, it's not worth calculating reflective coefficients. 

 

UHF Connector (@ 465MHz)   /    N Connector (@ 465MHz)

Reactance = 19.2 ohms / 28.3 ohms

Resistance = 50.5 ohms / 49.55 ohms

Inductance = 45 nH / 45 nH

Capacitance = 16.4 pF / 21.4 pF

 

[Lscott]

53 minutes ago, marcspaz said:

 

Not until just now. LOL  Seriously, when I made the cables, I looked and didn't see anything horrible. 

I still use all of the cables.  So, I dropped two of them from the gear for a few minutes and put them on the analyzer.  The complete cables are almost identical.  The values are so close and near where they should be, that for what we do in GMRS, it's not worth calculating reflective coefficients. 

 

UHF Connector (@ 465MHz)   /    N Connector (@ 465MHz)

Reactance = 19.2 ohms / 28.3 ohms

Resistance = 50.5 ohms / 49.55 ohms

Inductance = 45 nH / 45 nH

Capacitance = 16.4 pF / 21.4 pF

 

Doesn’t look much different. Thanks for doing the checks.

[tweiss3]

For what it's worth, DX Engineering's 400MAX cable has the same properties as Times Microwave LMR-400UF.

[axorlov]

400MAX has stranded copper central conductor like LMR-400-UF and is a direct burial like LMR-400-DB (which has a solid aluminum copper-clad center conductor). The difference in loss at 450MHz is negligible between the two. There is must be a catch somewhere, but I haven't found it so far. I use 400MAX for the last 10 years buried and on the very hot roof in sunny CA.

[tweiss3]

I wouldn't say negligible, 2.7 vs 3.3 db/100ft at 450MHz is something. It gets worse going up, 3.9 vs 4.7 at 894MHz.

I have a lot of 400MAX in use right now, but the repeater is going up on 1-1/4 hardline, and I'm in the process of swapping many things over to hardline.

[Newb]

I found this website very helpful in decision making.

https://www.timesmicrowave.com/Products/Cables/LMR_®_High_Performance_/LMR®_Ultra_Flex/

[WRUU498]

I recently wrote an article on this very topic. You can find it here: http://ogdenarc.org/downloads/Transmission Lines - Setting the Record Stright.pdf  Included in this article I also cover connectors which for GMRS should be an important consideration.  I've also attached it here.

1225397544_TransmissionLines-SettingtheRecordStright.pdf

[CentralFloridaGMRS]

How about Messi & Paoloni  Cable? Getting ready to install my roof Antenna soon 

[Lscott]

13 hours ago, WRPG818 said:

How about Messi & Paoloni  Cable? Getting ready to install my roof Antenna soon 

That’s an Italian supplier but it tells us nothing about what specific cable you’re looking to install. It makes a huge difference.

Coaxial Cable Attenuation Chart.pdf

[SteveShannon]

21 hours ago, WRPG818 said:

How about Messi & Paoloni  Cable? Getting ready to install my roof Antenna soon 

They make very high quality cables, but as LScott points out there’s much more to it than picking a good manufacturer.  Every different cable type has a characteristic which indicates the loss rate (usually expressed as dB per 100 feet) for that cable over distance for a specific frequency.  Generally speaking the loss rate goes way up as the frequency increases.  If you only need six feet you might not have to be too choosy, but if you’re running 200 feet through LMR400 for a GMRS repeater you could easily end up losing 75% of your power in cable losses. 3 dB loss over 100 feet is the same as losing 50% of your power. 6 dB over 200 feet is 75% loss. 

So, by all means select from a high quality manufacturer, but look at their complete catalog to see what they have that will work well for your use case.  Also generally speaking larger diameter cables have lower loss rates.  For professional installations people usually use something called hardline.

[Bande1]

KMR400 the knockoff LMR400 on Amazon, I measured the loss at 3% per 10ft on VHF. That's like, IDK, about 1.8dbi @ 100ft. Which is slightly better than real LMR400. Ive been very pleased with it. I don't exactly have a lab quality SWR meter though.

 

[Lscott]

8 hours ago, Bande1 said:

KMR400 the knockoff LMR400 on Amazon, I measured the loss at 3% per 10ft on VHF. That's like, IDK, about 1.8dbi @ 100ft. Which is slightly better than real LMR400. Ive been very pleased with it. I don't exactly have a lab quality SWR meter though.

 

Besides the cable losses there are other factors you need to consider. The cable will be installed outside so it has to be water/weather resistant. The jacket has to be UV resistant too or it will rapidly deteriorate. Finally you need to be concerned with the quality and installation of the connectors if the cable comes with them.

[SteveShannon]

On 12/28/2022 at 6:13 AM, Lscott said:

Besides the cable losses there are other factors you need to consider. The cable will be installed outside so it has to be water/weather resistant. The jacket has to be UV resistant too or it will rapidly deteriorate. Finally you need to be concerned with the quality and installation of the connectors if the cable comes with them.

This^^^^

 

[SteveShannon]

On 12/27/2022 at 9:20 PM, Bande1 said:

KMR400 the knockoff LMR400 on Amazon, I measured the loss at 3% per 10ft on VHF. That's like, IDK, about 1.8dbi @ 100ft. Which is slightly better than real LMR400. Ive been very pleased with it. I don't exactly have a lab quality SWR meter though.

 

Well, real LMR400 has losses of 1.5 dB/100 ft at 150 MHz or 1.9 dB/100 ft at 220 MHz, so I don’t know that I would accept that as better than real LMR400 from Times Microwave.  

http://www.signalcontrol.com/products/timesmicrowave/Times_Microwave_LMR400.pdf

[Bande1]

On 12/29/2022 at 10:58 AM, Sshannon said:

Well, real LMR400 has losses of 1.5 dB/100 ft at 150 MHz or 1.9 dB/100 ft at 220 MHz, so I don’t know that I would accept that as better than real LMR400 from Times Microwave.  

http://www.signalcontrol.com/products/timesmicrowave/Times_Microwave_LMR400.pdf

I had a table showing LMR400 8% at 25ft. KMR400 is doing 7%. But even still its less than a $1 a foot, thats pretty hard to beat.

[Bande1]

On 12/28/2022 at 8:13 AM, Lscott said:

Besides the cable losses there are other factors you need to consider. The cable will be installed outside so it has to be water/weather resistant. The jacket has to be UV resistant too or it will rapidly deteriorate. Finally you need to be concerned with the quality and installation of the connectors if the cable comes with them.

Mines been out in the elements few months now doing awesome. Just made it through -20f windchills last week.

[marcspaz]

5 hours ago, Bande1 said:

I had a table showing LMR400 8% at 25ft. KMR400 is doing 7%. But even still its less than a $1 a foot, thats pretty hard to beat.

 

Percent? What is being measured in percent?

[Bande1]

On 12/31/2022 at 6:14 PM, marcspaz said:

 

Percent? What is being measured in percent?

Im getting a forum "ackchyually" vibe here. Are you being intentionally obtuse asking what's being measured? Its power loss. The entire point of this thread.

On specific measured frequencies, in this case 145mhz, KMR400 has less loss than the LMR400 calculator according to my surecom meter. Whether thats accurate IDK. Its close enough to make it worth buying to me.

why am I measuring at 25ft? because thats the length of coax I have to measure.

 

 

 

[SteveShannon]

1 hour ago, Bande1 said:

Im getting a forum "ackchyually" vibe here. Are you being intentionally obtuse asking what's being measured? Its power loss. The entire point of this thread.

On specific measured frequencies, in this case 145mhz, KMR400 has less loss than the LMR400 calculator according to my surecom meter. Whether thats accurate IDK. Its close enough to make it worth buying to me.

why am I measuring at 25ft? because thats the length of coax I have to measure.

 

 

 

Although I don’t know him personally, Marc isn’t the type to act that way. I think his question was because cable loss is usually described in dB, not percent and hearing it referred to as a percentage was slightly confusing. 

[Bande1]

17 minutes ago, Sshannon said:

Although I don’t know him personally, Marc isn’t the type to act that way. I think his question was because cable loss is usually described in dB, not percent and hearing it referred to as a percentage was slightly confusing. 

oh ok. my apologies.

[SteveShannon]

19 minutes ago, Bande1 said:

oh ok. my apologies.

No problem. Some of us here are the “well, actually“ types, including me, but I’ve noticed that Marc isn’t. He seems pretty friendly and humble. 
 

From a loss standpoint I’d say you’ve made your case for going with KMR400 over LMR400. I would also look at how well the cable will withstand weather, how the connectors are attached, and do be sure to seal them so they don’t admit moisture over time. That’s something I’ve noticed, that people install cable and everything works great but then it gradually starts worsening. These cables are sensitive to moisture and the pl259 connector is not sealed so you’ll need to do something to seal it. 
Good luck!

[WRVX790]

Well! 

Actually... 

And! this is a no0b talking/asking, here, so... 

 

I had purchased 15' of M&P Hyperflex 5, an M&P PL259 (will do the soldering myself) and a brass NMO mount for the antenna end for a 20W GMRS install above the headliner (the cable, not the radio) in my '16 F150... 

After reading this thread and most of it's links, I would rather, ACTUALLY use LMR400. 

Am I nuts? and where would I source the appropriately-sized PL259 and NMO? if needed. 

I really wish to push as many as the 20 watts from the radio as I can into the air. 

Thanks for any feedback. 

[marcspaz]

45 minutes ago, WhiskeyRomeo790 said:

Well! 

Actually... 

And! this is a no0b talking/asking, here, so... 

 

I had purchased 15' of M&P Hyperflex 5, an M&P PL259 (will do the soldering myself) and a brass NMO mount for the antenna end for a 20W GMRS install above the headliner (the cable, not the radio) in my '16 F150... 

After reading this thread and most of it's links, I would rather, ACTUALLY use LMR400. 

Am I nuts? and where would I source the appropriately-sized PL259 and NMO? if needed. 

I really wish to push as many as the 20 watts from the radio as I can into the air. 

Thanks for any feedback. 

 

 

Is this for a mobile install?

 

What NMO where you going to buy?  They are pretty standard... but there aren't too many that I am aware of that you can connect LMR400 directly to.  You may want something like this.

https://www.amazon.com/dp/B0BLMHJ338/ref=sspa_dk_detail_4?psc=1&pd_rd_i=B0BLMHJ338&pd_rd_w=rmjiK&content-id=amzn1.sym.88097cb9-5064-44ef-891b-abfacbc1c44b&pf_rd_p=88097cb9-5064-44ef-891b-abfacbc1c44b&pf_rd_r=Z692ND5PVAJ7M99DKEJC&pd_rd_wg=JaTt0&pd_rd_r=bf38e4e0-6457-4b78-aeaf-f3229a8dd933&s=pc&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWw&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExREVHQ1daWFZYOEkzJmVuY3J5cHRlZElkPUExMDE1NjEyMkRUMVA5OThLTjFONiZlbmNyeXB0ZWRBZElkPUExMDIwMjIzM0RQSVFJUk9DN1FQTCZ3aWRnZXROYW1lPXNwX2RldGFpbCZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

 

 

These are great PL-259 connectors.

https://www.amazon.com/PL-259-Connectors-Adapter-Connector-XRDS-RF/dp/B07V4RJS64/ref=sr_1_3?crid=3O4FEIU6300NT&keywords=PL-259+Connectors+Male+UHF+Type+Attach+Adapter+End+Connector+LMR400%2FRG8%2FRG8U%2FKMR400%2FBelden+9913%2F7D-FB+Pack+of+2+by+XRDS-RF(NOT+for+TV)&qid=1676695065&sprefix=pl-259+connectors+male+uhf+type+attach+adapter+end+connector+lmr400%2Frg8%2Frg8u%2Fkmr400%2Fbelden+9913%2F7d-fb+pack+of+2+by+xrds-rf+not+for+tv+%2Caps%2C78&sr=8-3