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I am planning to instal a multiband HF antenna. It most likely will be a traditional or an offset diapole. I have looked at the G5RV and the Windoms. The feed line to my radio will be around 75 ft or less. There are a lot of different types of coax cable out there that will work. Some cable is very efficient and expensive and some poor performers that are cheap. There are so many it is difficult to choose. I am looking for something that will be the "best bang for the buck" so to speak. Your experience could help save me a lot of time and trouble. Not to mention the added expense for buying a less than desirable cable. I have thought of using RG mini 8. Any suggestions...? Thanks, Nick |
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Nick, first let me state an old saying "You get what you pay for!" When it comes to the RF Transmission Feedline that connects the last load on Transmit and the first load on Receive in your Amateur Radio Station, I recommend that you do not skimp on performance or quality. This is because the first and most important point to understand in any RF Two-Way Communication Electronics Station is that you must "Optimize the Antenna System!" A few microvolts of RF ElectroMagnetic energy intercepted by the antenna, fed to the receiver and displayed on the ‘S’-Meter is not very strong. Also with a 100 Watt transmitter the 70.7VAC RMS and low current of 1.414 amps transmitted through a 50 ohm coax into your antenna (assuming a 1.0:1 SWR) is not much and you deserve all that you can get. You do this by getting the best quality coax with the best shielding. Basically your question is asking "Is a better grade of coaxial cable worth the price difference?" Based on the need for the best shielding in coaxial cable lines the simple answer is yes. The electromagnetic energy transmitted and received through your coaxial cable may escape. This is often referred to as 'leakage', 'radiation', or 'shielding'. My recommendation for your Medium Frequency (MF) 160 Meters and High Frequency (HF) 80 - 10 Meters coaxial cable to and from your active antenna should be made from one of the following:
If you do not want to buy the cable and the PL-259 UHF connectors and assemble it yourself there are some companies who offer them pre-assembled and I have included their URL: http://www.rfparts.com/coax_preassembled.html http://www.cablexperts.com/cfdocs/index.cfm?BSKT=0&USA_ship=1 Due to the dB loss of RG-8/X (RG-8 Mini) I would not recommend this for anything other than using is as short jumper cables inside your shack between equipment before any RF Power Amplifier. Usually short lengths of between 1' to 6' is normal. If you do have an RF Power Amplifier I recommend you use the coaxial cables previous listed for the jumpers after it. Regards, Larry |
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RG213 really good. Don't bother with cheap coax it won't please you for long. |
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BEST feedline you will ever run is ladderline,coax is lossy and will not put that signal out the way you seem to want.based on test ran by arrl and numerous others for multi band you first need a good antenna tuner with a strong balun,my dipole loss comparisons matched their comclusions.i have an 80 mtr. dipole up and a 40 mtr. dipole flat top,40 mtr. is at 40 feet up,length is 66 feet,with coax i had 8214 up,loss was these figures,7150 mhz 0.19 db loss,at 18140 loss was 6.97 loss,on 14270 loss was 5.35.now after going to 100 foot of ladderline these are the changes i ended up with(7150 0.07 loss),on 18140 0.31 loss,14270 is 0.15 loss.weight factor greatly reduced as coax was about 9.6 lbs,ladderline around 2.5 lbs.using 1500 watts in 7 years and the laddeline still going strong.if arrl member look in the archives for APRIL 2002 AND READ- A BALANCED,EVERYDAY APPROACH TO ALL BAND BLISS,PAGE 47.FIGURE COST OF MONEY YOU SAVE BY USING HOMEBREW YOUR OWN,FORGET THE AFTERMARKET PRODUCTS.468 DIVIDED BY FREQUENCYS YOU WANT,may have enough room for a 80 mtr. dipole so put one up.my dipoles are used on 10 through 80 just fine.to many rare dx gotten on this and i made my own. |
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RG-8X is fine if you're talking about a G5RV and 75 ft though I think a G5RV traditionally has 70 ft of coax. Of course there's nothing to prevent you from using lower loss, larger/heavier coax then RG-8X but on the HF bands the loss is much less then on the VHF bands where 231/LMR would be preferred. If you are willing to spend more or find a good deal on lower loss coax, then I see no reason not to use it, but if you're looking to get it functioning well for a reasonable cost, going better on the coax probably won't make a difference. My G5RV has RG-8X. You can find the antenna that I use by searching ebay for True-Talk G5RV. Over 14k contacts logged in just over 18 months using that antenna at my home in NJ. K2DSL - David |
