> Now let us consider RF. 30 mhz is the worst case for HF amp use.
> All ratings below are assuming 1:1 swr (VERY IMPORTANT) and 40 deg. C
ambient.
> RG-58 350 watts
> RG-213 1500 watts
> RG-8X 300 watts
> RG-217 3900 watts
Phil,
Answer this question please. At 1500 Watts, your RMS RF voltage is 273.86
Volts.
So why do you say that RG-58 is only good for 350 Watts. Even the crappy
stuff you mention is capable of handling 300 Volts RMS. 273.86 Volts RMS is
less than 300 last time I checked.
> All coax has loss, which is dissapated in heat. Add significant swr
losses and
> the dielectric heating begins. This causes migration of the center
conductor
> toward
> the outer conductor, especially where the coax makes a turn. Then you have
an
> increasing spiral of more heating at the point of the impedance bump in
the
> line.
Agree with that.
> >
> > > My application is a 12" run of coax from the output of my Pi-L tank to
the
> > > vacuum antenna relay which could handle at least 1500 watts out, key
down.
>
> The RG-8X is a foam dielectric cable, and is less robust @ RF and only .3
db
> less loss per 100' than solid dielectric RG-58. Making bends with foam
> dielectric cable inside an RF deck is an invitation to conductor migration
due to the
> ambient
> heat in the deck.
Good point. I never thought of that. But please explain how RG-58 cannot
"handle" 1500 Watts of RF which is only an RMS voltage of 273 Volts.
73,
Jon
NA9D
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