22 replies to this topic

[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 you 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 hardline ,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

 

 

 

 

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[PastorGary]

JohnE has supplied photos of common connectors for member reference (added to post 1 above)..

 

The staff is opening up this thread for questions and replies for member convenience.

[kb2ztx]

Thanks guys thats a great topic. At the old shop i worked at we did a similar training day for our sales folks with the same setup. They didn't understand why it took us an entire day to run hard line vs 9913. After seeing the differences in cables they also understood why the cost was so much different.

[couger100101]

OK, so this is what I'm looking at for my setup. 75' TM rg8/213 mil spec. Browning 410-490Mhz uhf fiberglass land mobile omni base antenna, and for now mxt105. Plan on upgrading the radio later. Is it safe to say I should be fine? I'll be about 35' up. 

[couger100101]

Just scored the mother load in cable. Free! Belden 9913.

[PastorGary]

Please keep in mind that Belden 9913 has fairly high losses at GMRS frequencies. My old Belden chart from the early 1990's shows a 9913 loss of approximately 3.08 dbi for roughly 100 feet.  Compare that to Hardline LDF4-50A cable at approximately 1.465 dbi loss for 100 feet.
 

[couger100101]

Please keep in mind that Belden 9913 has fairly high losses at GMRS frequencies. My old Belden chart from the early 1990's shows a 9913 loss of approximately 3.08 dbi for roughly 100 feet. Compare that to Hardline LDF4-50A cable at approximately 1.465 dbi loss for 100 feet.

I understand that. I can deal with a little loss for the price. Lol. I was on a text line loss calculator and played around on it with different feedlines. I should only need about 60'. If I remember right the loss was between 1.7 and 2.1 at that length. Free is hard to come buy for feedlines. Lol. As I get more into it, I'll upgrade too.

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[Jones]

Free is ALWAYS the right price.  ...and if your 213 is free, then you can afford to buy a slightly better antenna to make up for the loss.

[couger100101]

Yes! I love free. All good cable, they just don't have room for pre cut lengths. I already bought an antenna. Ed Fung. Dbj- uhf. Should be here Monday or Tuesday. Can't wait. From the loss calculator 9913 has a slight less loss then the 213.

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[Jones]

You're right couger37, (binary?) at UHF frequencies, 9913 has slightly less loss than 213.  I see you were even talking about Free 9913.  I just had 213 on my brain the other day, since I had just replaced a chunk of it at an AM broadcast station.  Free is still the right price, regardless of coax type.

 

Yes, a 12 foot RG-213 jumper will eventually burn out when you're running 500 Watts at 1.39 MHz. (Keep in mind that AM radio stations use 125% peak positive modulation, so 500 Watts is actually 2500 Watts PEP, continuous keydown, 24/7 classic rock. Cable eventually melts and arcs through. I might need to move that jumper up to half inch Heliax.

[couger100101]

You're right couger37, (binary?) at UHF frequencies, 9913 has slightly less loss than 213. I see you were even talking about Free 9913. I just had 213 on my brain the other day, since I had just replaced a chunk of it at an AM broadcast station. Free is still the right price, regardless of coax type.

Yes, a 12 foot RG-213 jumper will eventually burn out when you're running 500 Watts at 1.39 MHz. (Keep in mind that AM radio stations use 125% peak positive modulation, so 500 Watts is actually 2500 Watts PEP, continuous keydown, 24/7 classic rock. Cable eventually melts and arcs through. I might need to move that jumper up to half inch Heliax.

Absolutely. That's just a bit of juice running there. 1/2" or even 5/8" might be better. Just sucks when you have to pay that price. Ultimately it will be worth it in the end. I happen to get lucky and talked with a local commercial installer and dealer and they just didn't have the room to store precut feeds. I'll have a variety of lengths that should fit my needs at the moment. I will also share the wealth with family and friends that are joining me on the air.

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[JohnE]

2 additions

1/4" and 3/8" superflex 

1/4  losses are 2.2dB/100' @150Mc and 4.0 @450Mc

3/8  losses are 1.5dB/100' @150Mc and 2.65 @450Mc

these are great for making jumpers w/o the leakage of braided cables.

will post some new pic when I get all the cables and connectors together

[Corey]

2 additions

1/4" and 3/8" superflex 

1/4  losses are 2.2dB/100' @150Mc and 4.0 @450Mc

3/8  losses are 1.5dB/100' @150Mc and 2.65 @450Mc

these are great for making jumpers w/o the leakage of braided cables.

will post some new pic when I get all the cables and connectors together

 

I never read to the bottom of this thread, just wanted to share my 1/2" Heliax plumbing job on this part 90 DMR repeater

 

[n4gix]

That's a lovely job, Corey!

[JohnE]

little overkill but I like it. nice job. 

how do you find the right angle connectors hold up to power? I have never liked using them.

[Corey]

little overkill but I like it. nice job. 

how do you find the right angle connectors hold up to power? I have never liked using them.

 

I have not had any issues with Comscope, I can't say that for RFS, several have shorted internally.

 

That cable job was to cure some issues with a paging transmitter next to me getting into the amp, it did solve the issue. I am sure i could have used something smaller but i had a ton of 1/2 on hand.

[Kugellager]

I know this is an old thread but I found this calculator really useful for estimating cable losses in various type of coax.

https://www.qsl.net/..._Calculator.htm

John
];’)

[kidphc]

Don't forget. Connectors. Boy do the losses add up with those.

[JohnE]

Don't forget. Connectors. Boy do the losses add up with those.

in the grand scheme of things it's pretty negligible  N connectors are typically 0.15 loss @10Gc, now dumb that down to 400Mc and it's irrelevant.

[kidphc]

in the grand scheme of things it's pretty negligible  N connectors are typically 0.15 loss @10Gc, now dumb that down to 400Mc and it's irrelevant.

True. that did a calculation, with all the pl259 connectors, and lightning arrestor and it came out to a little less then a dB. Sadly, still came out almost to a 4dB loss (estimated) with a 100ft run of LMR400.