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For some very general guidelines:VHF/UHF Good quality RG58 if low power and a short distance, less than 10 to 15 feet. OK for mobile installations where the run is short. HF 100w or so RG58 up to 75 feet. RG8X up to 100FT.RG8 (OK)/RG213 (better)/LMR400 (better still) for higher power and longer runs for HF, VHF, UHF. ON HF the problem is voltage break down at higher power. For VHF and more so for UHF, the problem is usually attenuation or signal loss.Another thing to consider is the quality of the cable. Poor quality cable can waste your transmitted and received signal to an astonishing extent. Cable loss is usually stated in db per 100ft at a given frequency. The cable makers websites are usually a good place to find information on a given brand and type of coax. A 3db loss means that you loose one half of your transmitted and received signal. Mystery cable marked with what ever type can be either very poor or good. You just can not tell without testing it.
I've used every type of coax on HF, VHF, & UHF through the years and I agree 100% with AC5WA and the suggestion I make to you is to never, never, skimp on your coax and always buy the very best you can afford and that also goes for the connectors too. Never buy off-brand coax or connectors. I only buy Beldon and Times Microwave Systems coax and I prefer the LMR400. The LMR400 is a direct replacement coax for RG-8 and 9913. It has a 85% velocity factor which I like for VHF and above work. It's very flexible and has about twice the RF shielding than the typical single shielded coax. This is especially important when running adjacent cable runs. The LMR400, depending on it's installation, can have a outdoor service life of over 20 years. The connector and the installation of the connector is also a very important part of the transmission line. I prefer Amphenol connectors because I have had less issues with them compared to off-brand connectors. Good Luck! de KB5LYR
I totally agree with both of you 100%.I use LMR400 for HF (42') and VHF/UHF (45').Testing and not skimping on putting out money on cable has given me peace of mind that I have done the best I can on purchasing a good, solid coax cable.You get what you pay for....Thank you both!Tony GilreathKE4TNRSouth Jordan, Utah
I use LMR-400 foe my 2M as well as my HF. I’ve had good luck with it. I run it through 1″ conduit to WX proof it and so far, no issues.
Agree with all the best coax its the lower looser. I am using Aircon semi air dielectric or foam from Belden, for VHF and UHF dxing. For HF i am lately redescovering the pleasure of work with 450 Ohm lader lines, i am building W8JKs and Delta Loops horizontal multiband antennas that are very rewarding in NVIS operation and emergency comunications in Europe. I know that for long runs the lader lines are also suited for VHF-UHF, specialy with QRO and EME operation, abcoarse if you want Top Gun coaxial go for the “rigid coper pipes” there are plenty of scrap from Cellphone towers that are great for us Hams. 73
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