Coaxial Cable Selection Help - High power, High Shielding

[astro10]

Hello,

Is there a good reference for which coaxial cable to use for a given power, frequency, and shielding desired?

I am looking at something to use with ~1kW at ~1.5MHz. Currently just a regular RG58 is used, which leaks RF noise everywhere into the lab, and gets quite warm. Visiting Pasternack's website, for example, I can a whole host of options that have >90dB of shielding and will handle the 1kW power, with prices varying over an order of magnitude, with no clear difference between options. Currently RG142 looks like a decent option, but maybe there is something else way cheaper that would work equally well.

Thanks!

[vk6zgo]

Hello,

Is there a good reference for which coaxial cable to use for a given power, frequency, and shielding desired?

I am looking at something to use with ~1kW at ~1.5MHz. Currently just a regular RG58 is used, which leaks RF noise everywhere into the lab, and gets quite warm. Visiting Pasternack's website, for example, I can a whole host of options that have >90dB of shielding and will handle the 1kW power, with prices varying over an order of magnitude, with no clear difference between options. Currently RG142 looks like a decent option, but maybe there is something else way cheaper that would work equally well.

Thanks!

1kW at 1.5MHz is equivalent to many lower powered AM broadcast Transmitters.
Broadcast practice is to go for "overkill", using cables rated well in excess of actual requirements.

You might be battling to get rid of the RF in the lab, no matter what you do, as some may leak from your source & load.

[edpalmer42]

Wouldn't RG8 do the job and be a lot cheaper than RG142?  Look for one that has a foil/braid shield to get the best shielding.

Ed

edit:  e.g. Belden 9913 - foil/braid - power 4KW @ 5 MHz - Mouser ~$200 for 100 ft. - 4 in stock - other lengths in stock

[bb37]

RG8 is the standard for amateur radio stations running 1500 watts at 1.8 to 30 MHz. RG8 should be able to handle up to 4 kW.

RG213 is a step up with a little better shielding and about the same power handling capacity.

RG214 has even better shielding.

Belden 9913 and Times Microwave LMR400 have even better shielding.

All of these are fairly large cables, approximately 0.405 inches in diameter, with varying degrees of flexibility. I would stay away from small diameter cable like RG58 or RG142 if I was running 1 kW. They might have the rating for that, but they are kinda on the ragged edge especially if you have an impedance match problem.

[astro10]

Thanks for the recommendations!

The L Com CA-195R looks like a good candidate.

>90 dB of shielding
2.5KW peak

And its quite cheap

[kj7e]

If you can use RG8 size cable then LMR400 is hard to beat.  A thinner alternative is LMR230, has the same 100% foil + heavy braid as LMR400 but its RG8X size and will handle 1.5KW at 30MHz.  They make a more flexible version as well, only difference is a stranded center conductor which adds a slight amount of attenuation.  Personally, I would not run 1KW though anything smaller than LMR240 (RG8X size).