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

[WRVX790]

Yes, marc, it is, and there are two different routes I can take with this. 

I know that the 400 is pretty large in o.d. for a mobile install, but!

 

Earlier, I was thinking of not using the mount plate I show in another thread (and instead go right through the roof for a better installation and improved ground plane) I see I can use the plate for the NMO required for the "oversize" LMR400 cable because I don't think I'm going to be able to make the connection fit between the aluminum roof and the headliner. That would require a 90* deal (which would be doable with the M&P .212" coax which I've already soldered to another NMO). 

 

So, now! I can still use the mount plate, the larger, straight NMO/SO-259, then drop the LMR400 run straight down outside the truck from the third brake light/sandwiched mount plate/truck cab roof to run between the truck bed and the rear of the truck cab, then, *underneath* the cab! and then pop up into the cab near the dash where the radio will be. *ponders* This may be easier to do since it's a pickup truck rather than a car, and the coax drop would be centered, widthwise of the truck. (apologies for any confusion, but I think this would be doable).

 

I do appreciate your help. With the NMO and the (2) PL-259 all I need now is the appropriate length of LMR400 (or whichever variant is best suited to a mobile install where no radii need be tighter than 2"...

 

G'dang. This could be really neat. 

[Sshannon]

I wouldn’t do an SO-239 to NMO fitting if it’s going to be exposed to the weather, unless you do an excellent job of weatherproofing.  I would do an N fitting on the outside.  They are a sealed fitting.  And then I would order the right length of LMR 400 with a factory end on each end.

Actually, I would just use a factory cable with an NMO fitting all sealed up on the end of it.  I know it’s going to have more loss per 100’ than LMR400, but for a 13 or 15 foot cable it’s inconsequential.

[gortex2]

You are way over thinking this. A standard quality NMO mount will be fine for the vehicle. The Laid mount that has been linked in other posts is perfect for your use and will cost less and perform just as well. There is absolutely no reason to use LMR in a vehicle install. Even in our command posts with many radios we dont run LMR. Its all quality NMO mounts. They are made to go above the headliner and take about 5 minutes to install in most new vehicles. 

[WRVX790]

3 hours ago, Sshannon said:

Actually, I would just use a factory cable with an NMO fitting all sealed up on the end of it.  I know it’s going to have more loss per 100’ than LMR400, but for a 13 or 15 foot cable it’s inconsequential.

 

Thanks Steve. What do you mean by "factory cable"? Yes, I know what that implies, factory-made complete with fittings and all ready to go, but which cable type?

I ask, because I made the mistake of running numbers across a line loss calculator posted earlier in this thread, and the results were surprising.

Assuming a 1.5 SWR, my 20W radio, 15-foot run and 462 MHz... 

RG-58 - 14.3 watts | LMR240 - 16.4 | LMR400 - 18.0 | 

Then there's "RG-8" which depending on manufacturer can vary but the Belden 9913 (10AWG solid core) on the same line loss calc - 17.9 watts 

So you can see the impetus to my overthinking... when I'd like to get to the antenna itself every single watt possible, where possible. 

Of course there's much I need to learn as you fellers are pointing out. 

[gortex2]

Your using a CCR mobile and your worried about a few watts. Power isn't everything in UHF. Throw an NMO Mount in and hook it up to the radio and use it. That 5 watts will do nothing noticable. 

[Sshannon]

6 minutes ago, WhiskeyRomeo790 said:

 

Thanks Steve. What do you mean by "factory cable"? Yes, I know what that implies, factory-made complete with fittings and all ready to go, but which cable type?

I ask, because I made the mistake of running numbers across a line loss calculator posted earlier in this thread, and the results were surprising.

Assuming a 1.5 SWR, my 20W radio, 15-foot run and 462 MHz... 

RG-58 - 14.3 watts | LMR240 - 16.4 | LMR400 - 18.0 | 

Then there's "RG-8" which depending on manufacturer can vary but the Belden 9913 (10AWG solid core) on the same line loss calc - 17.9 watts 

So you can see the impetus to my overthinking... when I'd like to get to the antenna itself every single watt possible, where possible. 

Of course there's much I need to learn as you fellers are pointing out. 

That difference in power will make almost zero difference to range.  I know that’s counterintuitive, but it’s true.

Yes, I mean a cable and NMO mount that are permanently constructed and sealed to each other by a well respected manufacturer.  Look at a place like DXEngineering or Ham Radio Output to see what companies like Larsen or Comet or even Midland offer.

[gortex2]

Here is a perfect mount for your radio. Just add a PL259 to Mini UHF adapter and be done. 

https://theantennafarm.com/shop-by-categories/shop-all/mobile-antenna-mounts/nmo-mobile-antenna-mounts/266-permanent-hole-mounts/283-nmo-3-4-hole-mounts-mini-uhf/12818-larsen-nmokhfcxmpl-detail

Antenna Farm is a great place for decent quality mounts for the hobbyist. 

[marcspaz]

7 hours ago, Sshannon said:

Actually, I would just use a factory cable with an NMO fitting all sealed up on the end of it.  I know it’s going to have more loss per 100’ than LMR400, but for a 13 or 15 foot cable it’s inconsequential.

 

7 hours ago, gortex2 said:

You are way over thinking this. A standard quality NMO mount will be fine for the vehicle.

 

I was thinking this myself, but held off on posting.  I have done mounts with items I shared, but they were for MCV's and portable outdoor setups.  They are a bit unruly in a classic POV install.

 

3 hours ago, WhiskeyRomeo790 said:

Thanks Steve. What do you mean by "factory cable"?

 

There are a few people in here with some great understanding on how power impacts performance. Some PE's and EE's (active and retired).  There have been many write-ups about how power impact range and performance.  The reality is, unless you get a cable that is complete trash and the connectors aren't terminated correctly, you are going to be hard-pressed to detect (without precision measuring tools) between 5w and 20w... or 20w and 80w.  Depending on terrain and the other radio in the communications path, you may start to notice a difference 5w and 80w

To give you a real-world example, I normally have a 50w radio I use in my Jeep.  It puts out 46w actual.  My jeep is broken, so I put an antenna on my Ram and just hookup a 5w HT to it, which actually output 4.1w.  There is no noticeable difference in how far I can communicate.  I get about 26 miles away from my local repeater, regardless of if I use the mobile with 46w or the handheld with a mobile antenna and 4.1w.

 

Checkout this video.

 

If you're on a smaller budget, this is a quality setup to use.

https://shop.motorolasolutions.com/antenna-mounting-kit/product/0180300B02?gclid=Cj0KCQiAi8KfBhCuARIsADp-A57XNGO25cd1opmbSPPzSQVJvX0iIZ1gXkz4TJBk36t3Hh_xzWtzEiwaAi6iEALw_wcB

 

If you have a few more dollars for the budget, I would recommend this...

https://www.hamradio.com/detail.cfm?pid=H0-009384

If you don't want to drill holes in the roof, I personally use Comet and Diamond complete mounts, like this...

https://www.hamradio.com/detail.cfm?pid=H0-006519

[WRVX790]

9 hours ago, gortex2 said:

Your using a CCR mobile and your worried about a few watts. Power isn't everything in UHF. Throw an NMO Mount in and hook it up to the radio and use it. That 5 watts will do nothing noticable. 

 

Yes, power isn't everything. The most important thing might first be an antenna placement that gives unobstructed line of sight (as high as it can be, in this case, on a vehicle) -and- with a good ground plane. Again, first things first. 

I already have a good NMO, but I've soldered M&P Hyperflex 5 to it, using marine-grade waterproof heatshrink afterwards, and after dilating the orifice in the NMO fitting's plastic cable cover to accept the thickness of the heatshrink over the .212" M&P cable. I would like to seal further (but don't know which substance to use) the plastic cover-to-bottom-of-NMO... but only if that were to be outside the cab of the truck, i.e. mounted using the Larson vehicle mounting plate I've pictured in another thread... 

As I mentioned earlier, I made the mistake of using a line loss calculator. Then I got carried away. You will please excuse the exuberance in my discovery of perhaps being able to use not only the best possible antenna placement, but also a superior cable with minimal loss! Wow... wouldn't that be neat. Again, carried away...

 

I thank you, Steve S and especially marcspaz for explaining what really matters: a good antenna (I can use either one of two, depending on my environment: a Midland 3dB Ghost antenna or a Midland MXTA26 (which I prefer), well-positioned on the vehicle, and this would trump any minute gains in wattage. I thought I knew this already, as explained, with *proof* by Randy/OffroaderX/N.A.R. Prods in one of his amusing and informative videos. 

 

 

6 hours ago, marcspaz said:

The reality is, unless you get a cable that is complete trash and the connectors aren't terminated correctly, you are going to be hard-pressed to detect (without precision measuring tools) between 5w and 20w... or 20w and 80w.  Depending on terrain and the other radio in the communications path, you may start to notice a difference 5w and 80w

To give you a real-world example, I normally have a 50w radio I use in my Jeep.  It puts out 46w actual.  My jeep is broken, so I put an antenna on my Ram and just hookup a 5w HT to it, which actually output 4.1w.  There is no noticeable difference in how far I can communicate.  I get about 26 miles away from my local repeater, regardless of if I use the mobile with 46w or the handheld with a mobile antenna and 4.1w.

 

Thanks, marc, a ton... that was what I needed to hear from the get-go. 

Now I can go ahead and not use the external mounting plate from Larson Electronics, and go ahead with the labor-intensive procedure to mount my NMO/Hyperflex5 through the roof of my truck. I say "labor intensive" due to the dismantling of my truck's interior to simply lower the hard headliner. 

This will be the far-cleaner install, should result in what I hope will be a superior ground plane and with a decent antenna placed as high as is practicable. Besides, the 20-watt Wouxun KG-XS20GPlus transmits more than it's advertised wattage, anyway. Again, as demonstrated so aptly by GMRS' Greatest Living YouTube Hobo...

Just trying to climb the steep learning curve and to do the best possible install that I can and within my means. 

Thanks again for your learned replies. They really have been helpful. 

Well, actually... really really helpful. 

 

[Lscott]

Just a comment here about power verses range. Most of the remarks in general are true in favorable conditions. However where power may be a significant factor is in fringe conditions. I'm not talking about at the limit of operating range. I'm thinking more along the lines of cases where signal attenuation could be high. Examples operating in heavy foliage areas, heavy rain, inside of building with radio wave absorbing materials  etc. I don't see much in the way of usage experience mentioned under those conditions.

 

[marcspaz]

That's because it doesn't matter what is attenuating the signal (other than the curvature of the earth), you still have to quadruple your power to increase your signal by 1 S-unit. 

 

I know that you are already familiar with this, but I will explain for the new people.  There is a standard in radio communications about intelligibility of radio communications. It is called the 5/9 scale. 0 to 5 for voice clarity and 0 to 9+ for signal strength in s-units. It is said that while a 2/1 signal provides partially usable comms, the lowest "reliable" communications happens at a 3/2 (or 32) and the best is a 5/9+ (often called 599, 59+20, 59+40, etc.).

If you are transmitting a 15 watt signal and I can tell you are there, but I can't make out what your saying or enough of what you are saying, I am probably receiving you at 1 s-unit or less.  You are going to need to add at least 2 S-units before there is a chance I can make out about 60%-70% of what you are saying.  You would really want a full 3 s-units for conversational communications.  That translates to jumping from 15w to 240w.  If you are truly fringe and your signal is attenuated by trees, buildings, etc. to the point that we can't talk, adding another 5 watts isn't going to do anything.  Jumping to 45w-50w still isn't going to make it so you can have a conversation if I can't make out anything you're saying at 15w.

 

I did a write-up about this in 2019 -

 

 

[Lscott]

Anyway back on topic here. I did an analysis of an antenna system I want to install on my new ride. I had a choice between several different cable types and lengths along with antenna and mount. I wanted a roof rack type mount so the antenna had to be a 1/2 wave type that doesn't require a ground plane.

The goal was to see which combination was the best case compared to what I can get to fit. I have to route the cable around a tail light assembly and it has to be behind the rear hatch. It's a very tight fit for the cable and I'm not into drilling any holes. 

I went a bit overboard with the analysis but gives you an idea what things to consider. For example some of the cable loses can be made up, sort of, with a higher gain antenna. That's one of the trade offs you can make.

It looks like what will work is the short coax cable mount, using RG-316 thin coax cable, with an RG-8 mini cable extension. Keeping the mount with the RG-316 coax cable length short makes a difference. The mount using RG-58C is a bit better but the difference wasn't more than a few percent different from the one I think will fit best.

If range was ONLY a function of power then the range change varies as the square-root of the ratio of the powers. I calculated a likely range change based on the square-root of the ratios of power loss/gain between the different configurations.

One point about the cable connectors. They are all RG-8 mini type, including the one on the end of the coax cable used on the mount. It comes with a RG-8 mini to PL-259 adapter. The RG-8 mini adapter is a constant impedance type, the normal PL-259/SO-239 are not, thus there is likely to be little in the way of SWR issues using RG-8 mini through out the system. The adapters are rated up to 2.5GHz and the insertion loses are very low.

 

Diamond C101 Cable Assembly.pdf Diamond C110 Extension Cable.pdf Diamond K550 Luggage Rack Mount.pdf Mazda 2023 CX-5 Antenna System Analysis Rev 5.pdf SG7500A.pdf Coaxial Cable Attenuation Chart.pdf

[axorlov]

1 hour ago, marcspaz said:

There is a standard in radio communications about intelligibility of radio communications. It is called the 5/9 scale. 0 to 5 for voice clarity and 0 to 9+ for signal strength in s-units.

This RST scale/standard was developed 90 years ago to parametrize decoding of Morse code (continuous wave modulation) with human ear. It is not applicable to FM demodulators.

We've been through this already, and I don't want to pollute this thread. But we can start a new one.

[marcspaz]

54 minutes ago, axorlov said:

This RST scale/standard was developed 90 years ago to parametrize decoding of Morse code (continuous wave modulation) with human ear. It is not applicable to FM demodulators.

We've been through this already, and I don't want to pollute this thread. But we can start a new one.

 

There is nothing to discuss in a new thread.  If you think that quality of a radio signal being received can't be described by readability and signal strength on a sliding scale and that signal strength doesn't directly impact readability because someone is using frequency modulation instead of AM or SSB, you have said everything I need to know about your understanding of electronics. 

[axorlov]

 

17 minutes ago, marcspaz said:

If you think that quality of a radio signal being received can't be described by readability and signal strength on a sliding scale and that signal strength doesn't directly impact readability because someone is using frequency modulation

I did not say that^^^^

I'll try again.

One S-unit is when human ear can tell the difference between levels of AM signal. For FM demodulator the readability is how clear it can detect frequency/phase shift. Demodulator does not care about amplitude, and long as it has enough of it to detect frequency shift. Deviation plays bigger role than amplitude. S-units on RST scale are for amplitude. If you want to create RST scale for FM, the one S-unit (when human ear can tell the difference) will not be 4x of the power sent through the transmitter.

 

 

 

[marcspaz]

12 minutes ago, axorlov said:

One S-unit is when human ear can tell the difference between levels of AM signal.

100% incorrect.  S-units define received voltage at the receive front-end. 1 S-unit is equal to 0.20 μV (-121dBm). 

 

Also, a discriminator circuit converts FM signals to AM and extracts the information from the AM envelope. If there isn't enough detected deviation or inconsistent receive of the deviation, the discriminator cannot create a proper AM envelope, thus cannot extract the information. 

[axorlov]

2 minutes ago, marcspaz said:

1 S-unit is equal to 0.20 μV. 

And why do you think it is exactly 0.20μV over 50 Ohm load? I'll tell you, it's because this value roughly corresponds to the difference that can be detected by human ear after some "normalized" amplification. RST (RS) scale is about psycho-acoustics, not about electronics at all.

[marcspaz]

12 minutes ago, axorlov said:

And why do you think it is exactly 0.20μV over 50 Ohm load? I'll tell you, it's because this value roughly corresponds to the difference that can be detected by human ear after some "normalized" amplification. RST (RS) scale is about psycho-acoustics, not about electronics at all.

 

Dude, are you just messing with me? 

 

I think I'm being trolled by Alex... at 3AM. LoL

[axorlov]

7 minutes ago, marcspaz said:

 

Dude, are you just messing with me? 

Lolwhut? No, I'm not. S-meter calibration is different for HF and VHF. On HF frequencies S1 is 0.2uV, S2 is 0.4uV, S3 is 0.79uV and so on. On VHF it is 0.02uV, 0.04uV, 0.08uV... Why the 10x difference? Because it's not about microvolts at all.

Strength scale (the "S" in the RST):

1. Faint—signals barely perceptible
2. Very weak signals
3. Weak signals
4. Fair signals
5. Fairly good signals
6. Good signals
7. Moderately strong signals
8. Strong signals
9. Extremely strong signals

Where are the microvolts? It is all about acoustics.

[axorlov]

<dupe>

[Lscott]

3 hours ago, marcspaz said:

100% incorrect.  S-units define received voltage at the receive front-end. 1 S-unit is equal to 0.20 μV (-121dBm). 

 

Also, a discriminator circuit converts FM signals to AM and extracts the information from the AM envelope. If there isn't enough detected deviation or inconsistent receive of the deviation, the discriminator cannot create a proper AM envelope, thus cannot extract the information. 

Ah, a proper FM demodulation circuit includes a limiter stage designed to deliberately remove any amplitude changes, before the discriminator stage, so it response only to the frequency deviation.

For good discriminator performance there has to be sufficient signal amplitude to achieve full limiter action. 

https://www.arrl.org/files/file/Technology/tis/info/pdf/8506025.pdf

[Sshannon]

@axorlov, @marcspaz, and @Lscott

Thank you guys!  That was a truly interesting exchange on the signal strength meter and modulation types.  It made me want to learn more.  I knew that each S unit is 6 dB change, but I didn’t realize it was based on an absolute reference uV value, although in hindsight I should have.

[Lscott]

21 minutes ago, Sshannon said:

@axorlov, @marcspaz, and @Lscott

Thank you guys!  That was a truly interesting exchange on the signal strength meter and modulation types.  It made me want to learn more.  I knew that each S unit is 6 dB change, but I didn’t realize it was based on an absolute reference uV value, although in hindsight I should have.

It gets a bit more confusing when you include gain antennas in the mix. For example with a simple 1/4 wave antenna lets say your S-meter reads 2 S-units. Then switch over to an antenna with 6db of gain now your S-meter will read 3 S-units. Nothing on the TX end or path changed other than your antenna.

[marcspaz]

5 minutes ago, Lscott said:

It gets a bit more confusing when you include gain antennas in the mix. For example with a simple 1/4 wave antenna lets say your S-meter reads 2 S-units. Then switch over to an antenna with 6db of gain now your S-meter will read 3 S-units. Nothing on the TX end or path changed other than your antenna.

 

It's truly a wonderful thing about antenna design, isn't it?

[JohnE]

Quote

Lolwhut? No, I'm not. S-meter calibration is different for HF and VHF. On HF frequencies S1 is 0.2uV, S2 is 0.4uV, S3 is 0.79uV and so on. On VHF it is 0.02uV, 0.04uV, 0.08uV... Why the 10x difference? Because it's not about microvolts at all.

Strength scale (the "S" in the RST):

1. Faint—signals barely perceptible
2. Very weak signals
3. Weak signals
4. Fair signals
5. Fairly good signals
6. Good signals
7. Moderately strong signals
8. Strong signals
9. Extremely strong signals

Where are the microvolts? It is all about acoustics.

12 and 20dB sinad is all I care about. Where does it open and where does it close in CSQ or pl