On 1/6/18 2:09 AM, Jim Brown wrote:
On 1/6/2018 1:41 AM, Martin Sole wrote:
Anyone have an idea of the 30MHz power handling capability for RG6A/U
and Belden 9104?
RG-numbers are essentially meaningless -- the tell us nothing more than
approximate size and Zo. The Belden data sheet
https://catalog.belden.com/techdata/EN/9104_techdata.pdf
tells us that 9104 is a CATV cable, CCS center, shield is Al braid and
Al foil. Your guess is as good as mine for power handling. It's designed
for low power CATV systems where the signals are mostly UHF. It tells us
that DCR (resistance at DC) of the center is 4.45 ohms/100 ft, and 1.2
ohms for the shield. These values will increase (a lot) with frequency.
My WAG (Wild Assed Guess) is that these cables will be OK for 100W into
matched loads, but I'd be cautious with high power or poorly matched
loads. And remember -- the match that matters is that between the
antenna and the line.
0.9 dB/100ft, so 0.009 dB/ft - that's about 0.2% 1000W * 0.002 is 2W/ft
As Jim noted, that's in a matched system - Think of it as a series of
little resistors - 2 W/Ft is about 0.2 watts/inch. I think that will
get noticeably warm.
Another way to look at it is that the center conductor is 20 gauge
(copper coated steel). 1 kW at 75 ohms is 4 amps rms. Are you
comfortable running 4A through a steel 20 gauge wire with 1/8" of
polyethylene foam insulation?
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