Posted: 10/8/2011 12:40:23 PM EDT
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Needing to make a ~120' run from house up my short tower for VHF/UHF. What kind of coax would be best (from a $ of view, too) with as little loss as possible? I will be running my HT off of it right now, but I want to be able to use base unit later. What kind of connectors, PL-259,N,BNC would be best? Links?
73 |
| DOn't mean $30 cheap, just not $5 a foot heliax. My short (60') tower is around 60-70' from my house. I guess I may have to add 10' to my 20' next to the house and use that, then. Any more good ideas or things to watch out for? I do telco and computer stuff everyday, but I don't fool with coax much unless its like CATV/satellite type stuff (fconnectors). |
funny you should mention that...me and a new-ham buddy (got his callsign 2 days before me, even though I took the test 4 days before him ) plan on making roll-up j-poles next weekend while I'm cooking at the BBQ competition. We'll have a lot of free time in between beers so we figured we'd make some antennas. I planned on building them out of ladder line like all the popular internet-ham sites suggest, but put a short pigtail on at least one for portability purposes, and make the 2nd one on the tower-solid coax to the radio.
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LMR-400 would give you about 3 db loss for 120 feet on 440. It's about a buck a foot. LMR-600 would be better, about 2 db and it's about 3 bucks a foot. I used LMR-400 on HF (because I'm crazy like that). Love the stuff. I got it for about 80 cents a foot with connectors on it at a hamfest. |
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LMR-400 would give you about 3 db loss for 120 feet on 440. It's about a buck a foot. LMR-600 would be better, about 2 db and it's about 3 bucks a foot. I used LMR-400 on HF (because I'm crazy like that). Love the stuff. I got it for about 80 cents a foot with connectors on it at a hamfest. Well it sure can't hurt! |
| 400 size is really the break point for price vs performance. From there on up you're paying a lot for limited returns at the common frequencies. UHF or higher weak signal contest or EME station or the like might be a different story. Most on arfcom are ridiculously overconcerned with line loss. |
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I'm just with a 5w HT right now...If oyu lose 1/2 your signal to line loss with a mobile @50w you still have 25w...If I get the same loss then I'm fucked at 5w....thrying to maximize the little power I have till I get a bigger radio. 3dB is 3dB either way, but the difference in cables at this point isn't even close to 3dB. On FM I can guarantee that you'd never be able to tell the difference. According to the T-M loss calculator, at 446MHz, for a 120ft run the loss difference between LMR400 and LMR600 is 1.1dB. At 146MHz it's only 0.7dB. LMR600 will cost you roughly double what 400 will, just for the cable - plus connectors are much higher. You can save that much or more just by using N/BNC/SMA connectors instead of UHF/PL259s. As a comparison, let's say you went full retard and bought the biggest cable Times Microwave makes - LMR1700. For a whopping $1400 (or more) extra (plus jumpers and a lot of extra hassle), you'd save 2.8dB at 446MHz and just 1.4dB at 146MHz. On FM you'd be hard pressed to detect a difference of 2 to 3dB in normal operation. The total line loss for LMR400, for 120 feet on 2m is just 1.8dB. Just buy some 400 or a clone thereof, and put up a decent antenna. Antenna, connectors, adapters, etc etc will make 10x as much difference as any line loss you may have a phobia about. I'm not sure if it's humorous or tragic, that folks get really worked up over 1 or 2dB line losses when you can easily have that much or more loss in a single PL259 to SO239 connector junction on the 70cm band. Quoted:
funny you should mention that...me and a new-ham buddy (got his callsign 2 days before me, even though I took the test 4 days before him ) plan on making roll-up j-poles next weekend while I'm cooking at the BBQ competition. We'll have a lot of free time in between beers so we figured we'd make some antennas. I planned on building them out of ladder line like all the popular internet-ham sites suggest, but put a short pigtail on at least one for portability purposes, and make the 2nd one on the tower-solid coax to the radio.For less than the difference in cost between LMR400 and LMR600, you could easily get ~6dB of additional gain just by picking a good quality high performance antenna. It's ludicrous to discuss cable loss when you're picking a low-performance antenna to put at the end of that coax. |
| Gotcha, Gamma. Thanks for real-world numbers., it makes it easier to put it into perspective that way. I do want the best base setup I can get, but I'm not obsessing over a db here or there, but I will keep it to a minimum where I can at a certain pricepoint. The J-poles are experimentation purposes, and to have a portable should the need arise. What would you recommend for a good VHF/UHF permanent base station antenna? |
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Gotcha, Gamma. Thanks for real-world numbers., it makes it easier to put it into perspective that way. I do want the best base setup I can get, but I'm not obsessing over a db here or there, but I will keep it to a minimum where I can at a certain pricepoint. The J-poles are experimentation purposes, and to have a portable should the need arise. What would you recommend for a good VHF/UHF permanent base station antenna? The diamond X50A is recommended here. I have a comet GP-1 (shorter) and it is amazing. It's up in my attic and I can hit repeaters 40+ miles out and made an 85 mile simplex 2m qso in fm. THe comet GP-3 is longer and has better gain. |
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The diamond X50A is recommended here. I have a comet GP-1 (shorter) and it is amazing. It's up in my attic and I can hit repeaters 40+ miles out and made an 85 mile simplex 2m qso in fm. THe comet GP-3 is longer and has better gain. I replaced my Arrow J-Pole with a Diamond X50 after seeing it mentioned here. It did make a difference. At under 100 bucks, I think it's money well spent. |
| Pretty much any of the fiberglass two-section dual band antennas should be a pretty good performer on both bands. The long (~18') three section antennas I have not found to be very good on 440, but are good on 2m. Their height makes them more susceptible to damage from high winds and icing as well. |