Cable Asylum: Re: Some cautions about 9913 by Sean

I am 100% positive on my previous comments. In theory and on paper, 9913 is a phenomenal cable. We used to use 9913 quite a bit until we started having problems with it. Unfortunately, we didn't find all of this out until we had done quite a few installations. Then again, some of these guys were running these cables WAY beyond rated power handling capabilities, so that might have come into play. On the other hand, we have used REAL military grade RG-213 with as much as 10,000 watts ( that's RMS not peak ). We had NO problems doing this as long as the antenna system was VERY well tuned. As you might be aware, this is WAY, WAY beyond it's ratings.

The reason that i said "REAL" 213 is that there are many fakes out on the market that don't use a Type II non-contaminating jacket along with a lower grade of shielding. These will not have a mil-spec number on them or won't say "non-contaminating Type II jacket" on them. It's essentially RG-8 with a "prestigious" name on the jacket.

As mentioned, the original 9913 used a spiral polyethylene bead within the air-gap to keep the solid "hot" conductor centered. Later 9913 was changed to a stranded center conductor and called 9913F ( F was for flexible ). They have since made further changes in how the center conductor is supported.

My comments about 9913 "collecting" moisture or condensation are quite simple to see. Since the cable has an "air gap dielectric", the air inside the cable will be a certain temperature. Rapid cooling or warming of the cable or ambient air temperature will cause "sweating" within the cable itself. This is not uncommon in cables of similar design. This is the very reason why some high powered installations using "hard-line" are sometimes filled with gas instead of air. It is not nearly as sensitive to ambient air temperatures and also acts as a cooling agent to the center conductor.

Tubes would also develop internal condensation if they weren't "vacuum sealed". Can you imagine droplet's of water inside a container with hundreds / thousands of volts being pumped through it ?? I think not.

Most people that are serious about RF and "know their stuff" completely side-step 9913 when upgrading from RG-213 and shoot for either RG-393 Thermax ( silver plated stranded copper center with teflon insulation and two layers of silver plated copper shielding ), LMR or "hard-line". These are all much better, more reliable and present a more consistent impedance than 9913. Like 9913 though, LMR's bend radious is not nearly as easy to work with as RG-213 is. RG-393 is about the same to work with as 213 while offering greatly increased power handling. Hard-line is the lowest loss and highest power handling, but just plain doesn't bend. Sean
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