Swr change.

[WRCC711]

I have a question, the swr on my base radio has changed after installing a UHF lighting arrestor in line on my antenna cable (rg58) at the antenna mast. It has gone from 1.5 to 2.4. I double checked my fittings ( installed pl259 solder/crimp connectors ) for continuity with my multi meter which gave me a reading of 002 . A  very slight bit of resistance . I did the same check on both sections of cable with the same readings.  The arrestor is designed for uhf, it's the gas cartridge type ,I have a ground wire ran from it to a common ground stake where several other antenna are grounded. I know an swr of 2.4 isn't the end of the world,but I'm at a loss as to the increase. 

[WRYZ926]

I'm glad to hear that you redid the connections and that improved things for you.

While ABR makes excellent coax cables, their ABR240-UF is pretty much the same as RG-213. 

Line Loss per 100 Feet

RG-213 - 5.28dB, 70% loss

LMR240 (same as ABR240) - 5.40dB, 72% loss

LMR400 - 2.87dB, 48% loss

RG-58 - 9.16dB, 88% loss

Again, The calculations were made using 50 watts in and an SWR of 1.5. I used the https://kv5r.com/ham-radio/coax-loss-calculator/ to get those numbers. Your numbers will be different depending on the actual gain of your antenna.

Higher loss cable will actually show a lower SWR due to loss. Go with the best that you can afford along with the acceptable losses for your needs. I would go with the DX Engineering 400MAX or R&L Electronics Jetstream 400Flex before going with RG-213/ABR240/LMR240. 

ABR coax is good stuff and I use their cables for all of my portable/POTA setups. Check out the coax loss calculator I linked. It is very helpful.

 

[tcp2525]

4 hours ago, WRCC711 said:

UPDATE !

I decided to redo the connections I pre iously made,this time making sure to crimp the collars as best as I could,and taking care to fill the pin with as much solder as possible. While a continuity check yielded the same .002 my SWR has now dropped to 1.43. Not perfect but for this RG 58 I don't think it will get any better. I am looking as some custom cables fromABR industries. Their ABR 240-UF. I do appreciate everyone's input and help. 

Just a suggestion, instead of wasting money and time buying substandard coax and finding out it's not making you happy, just buy some 1/2" Heliax and save money and time. UHF isn't forgiving when it comes to feedline. 

[tcp2525]

4 hours ago, WRCC711 said:

UPDATE !

I decided to redo the connections I pre iously made,this time making sure to crimp the collars as best as I could,and taking care to fill the pin with as much solder as possible. While a continuity check yielded the same .002 my SWR has now dropped to 1.43. Not perfect but for this RG 58 I don't think it will get any better. I am looking as some custom cables fromABR industries. Their ABR 240-UF. I do appreciate everyone's input and help. 

Just a suggestion, instead of wasting money and time buying substandard coax and finding out it's not making you happy, just buy some 1/2" Heliax and save money and time. UHF isn't forgiving when it comes to feedline. 

[TerriKennedy]

On 5/9/2025 at 7:19 PM, WRYZ926 said:

RG-213 has 5.28dB/70% loss at 100 feet and LMR-400 has 2.87dB/48% loss at 100 feet. The calculations were made using 50 watts in and an SWR of 1.5. You can get away with using RG-213 but LMR-400 will definitely work better. 

Cheaper alternatives to LMR-400 is DX Engineering 400MAX or R&L Electronics Jetstream 400Flex. As @nokones stated, stay away from the cheap stuff from Amazon and eBay.

The cheaper stuff will have less ground shielding plus some use aluminum instead of copper shielding. You definitely won't get as  good of a solder joint on your connectors with aluminum shielding, if you can even get the solder to stick to it.

It's a trade-off between cost, ease of installation, performance during operation, and a bit of everyone's different opinions thrown in.

At work, I ran two 200-foot runs of Times Microwave LMR600 between the roof and our basement office. One was for a cellular repeater antenna (this pre-dated the pre-registration requirement, by the way) and the other was for a GPS antenna. I had to put a 10dB attenuator between the indoor lightning arrestor and the Wilson cellular amplifier or I'd overload its front end. The General Dynamics box the GPS antenna went into was perfectly happy with the GPS signal level. All the connectors were ordered from Pasternack, as were the LMR600 stripper and crimper. I have a leftover piece of LMR600 with an N connector on the end that I use as a walking stick.

OTOH, my entire (large) collection of home-use connector adapters cost less than two of the Pasternack LMR600 connectors. It's a trade-off between price, performance, and personal opinion. My repeater is currently using some no-name super-flex 400 (they can't call it LMR because that's a trademark of Times Microwave) to its temporary antenna. If the Commscope / Andrew fiasco ever starts producing antennas again, my DB420-B will be connected to the entry point lightning arrestor using 7/8" heliax with N connectors. My grounding consists of eight 8' long copper-clad steel grounding rods, 16' apart, with one end tied to the electrical service ground. The whole run from service ground to the antenna lightning arrestor is one continuous piece of #4 stranded copper with green insulation jacket except where the jacket was shaved to connect to the grounding post clamps, electrical ground, and lightning arrestor ground terminal.

Forgive the non-GMRS pictures, but they do show good (to me, at least) cable installation practices... You can't see the outdoor lightning arrestors as they're at the point where the cables are about to go through the roof penetration.

[tcp2525]

26 minutes ago, TerriKennedy said:

It's a trade-off between ease of installation, performance during operation, and a bit of everyone's different opinions thrown in.

At work, I ran two 200-foot runs of Times Microwave LMR600 between the roof and our basement office. One was for a cellular repeater antenna (this pre-dated the pre-registration requirement, by the way) and the other was for a GPS antenna. I had to put a 10dB attenuator between the indoor lightning arrestor and the Wilson cellular amplifier or I'd overload its front end. The General Dynamics box the GPS antenna went into was perfectly happy with the GPS signal level. All the connectors were ordered from Pasternack, as were the LMR600 stripper and crimper. I have a leftover piece of LMR600 with an N connector on the end that I use as a walking stick.

OTOH, my entire (large) collection of home-use connector adapters cost less than two of the Pasternack LMR600 connectors. It's a trade-off between price, performance, and personal opinion. My repeater is currently using some no-name super-flex 400 (they can't call it LMR because that's a trademark of Times Microwave) to its temporary antenna. If the Commscope / Andrew fiasco ever starts producing antennas again, my DB420-B will be connected to the entry point lightning arrestor using 7/8" heliax with N connectors. My grounding consists of eight 8' long copper-clad steel grounding rods, 16' apart, with one end tied to the electrical service ground. The whole run from service ground to the antenna lightning arrestor is one continuous piece of #4 stranded copper with green insulation jacket except where the jacket was shaved to connect to the grounding post clamps, electrical ground, and lightning arrestor ground terminal.

Forgive the non-GMRS pictures, but they do show good (to me, at least) cable installation practices... You can't see the outdoor lightning arrestors as they're at the point where the cables are about to go through the roof penetration.

Nice job, but I'm not sure why you would mount the stuff to a mini-split. Not good in my opinion.

[WRYZ926]

It's always a trade off when determining what type of coax to use. For the average person setting up a base station where the coax run is 50 feet or less then LMR 400 and equivalent is fine. Just like every type of antenna is a compromise. 

Go with what works best for your situation and that also fits your budget. Not everyone can afford LMR 600 or 1/2" Heliax cable.

[TerriKennedy]

18 minutes ago, tcp2525 said:

Nice job, but I'm not sure why you would mount the stuff to a mini-split. Not good in my opinion.

We don't have roof rights to anything else. We had to pay a one-time charge for the run of the cables across the roof and the roof penetration, plus annual inspection and any necessary maintenance.

It is also the highest elevation on the roof (unless we were to construct a tower, which a) isn't needed and b) would be prohibitively expensive). If this was for a GMRS project, then getting additional elevation would have been worthwhile. But for GPS we have a good view of the sky and the cellular extender antenna has line of sight to antennas of several carriers.

The L-channel was already there and provided a convenient mounting point for the antenna brackets. The cellular antenna is actually between the two units, while the GPS antenna is attached to the piping side of the mini-split but is comes with an ultra-flex N pigtail which we then connect to the LMR600 and put thick heat shrink with adhesive on the inside over the connection (as we did with the connection on the bottom of the cellular antenna). The unit to the right is top-exhaust and apparently defunct, and our mini-split has the antennas mounted on the inlet side, not the exhaust side, of the coils so they're not getting baked.

[WRUE951]

some 30 odd years ago i mounted a NMO UHF antenna in the center of a MasterCool Swamp Cooler sitting on top of a 3 story building...  Worked good and the antenna is still mounted where i left it when i left that job.