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LMR 240 is RG8X size wise just as LMR 400 is RG8.

The LMR cable is really designed for losses that occurs in coax in the VHF range and above. HF frequencies are better off with solid or stranded RG8X type coax even though the spec's you read on losses and velocity factors can make you believe otherwise. If you look up spec's on Times Microwave LMR, you'll see the frequency losses aren't listed for HF frequencies below 30 MHz but they are spec'd for frequencies way up to the GHZ range at 100ft lengths.

Either coax works but for a truck install, RG8X will be just fine. Nothing much will be gained or loss with lengths well under 30ft on a mobile install. RG58 is fine unless high power is going to he used.

I use RG213 for my HF mobile rig because I need something stiff like a solid conductor in a stranded type coax. I have part of the coax exposed underneath the antenna and the bigger coax doesn't flop around in the wind like RG8X would eventually leading to a short at the coax connector.

<blockquote data-quote="fourstringburn" data-source="post: 663706" data-attributes="member: 2920">LMR 240 is RG8X size wise just as LMR 400 is RG8.The LMR cable is really designed for losses that occurs in coax in the VHF range and above. HF frequencies are better off with solid or stranded RG8X type coax even though the spec&#039;s you read on losses and velocity factors can make you believe otherwise. If you look up spec&#039;s on Times Microwave LMR, you&#039;ll see the frequency losses aren&#039;t listed for HF frequencies below 30 MHz but they are spec&#039;d for frequencies way up to the GHZ range at 100ft lengths. Either coax works but for a truck install, RG8X will be just fine. Nothing much will be gained or loss with lengths well under 30ft on a mobile install. RG58 is fine unless high power is going to he used. I use RG213 for my HF mobile rig because I need something stiff like a solid conductor in a stranded type coax. I have part of the coax exposed underneath the antenna and the bigger coax doesn&#039;t flop around in the wind like RG8X would eventually leading to a short at the coax connector.</blockquote>

[QUOTE="fourstringburn, post: 663706, member: 2920"] LMR 240 is RG8X size wise just as LMR 400 is RG8. The LMR cable is really designed for losses that occurs in coax in the VHF range and above. HF frequencies are better off with solid or stranded RG8X type coax even though the spec's you read on losses and velocity factors can make you believe otherwise. If you look up spec's on Times Microwave LMR, you'll see the frequency losses aren't listed for HF frequencies below 30 MHz but they are spec'd for frequencies way up to the GHZ range at 100ft lengths. Either coax works but for a truck install, RG8X will be just fine. Nothing much will be gained or loss with lengths well under 30ft on a mobile install. RG58 is fine unless high power is going to he used. I use RG213 for my HF mobile rig because I need something stiff like a solid conductor in a stranded type coax. I have part of the coax exposed underneath the antenna and the bigger coax doesn't flop around in the wind like RG8X would eventually leading to a short at the coax connector. [/QUOTE]

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