"Owen Duffy" wrote in message
...
"Tam/WB2TT" wrote in
:

BTW, the LMR240UF makes for great patch cords. It has a stranded
center conductor. 1/4 inch cable that is rated at 1500W. The LMR240

From the spec sheet, the average power rating at 30MHz is 1240W. I assume
that is with VSWR=1, so that a further derating is required for mismatch.
For example, at VSWR=2, the heating at a current maximum is nearly double
that for a flat line, so the power rating might be more like 620W with
VSWR=2.

Of course, in SSB telephony, the average power is very low and the cable
is
probably limited by voltage breakdown at peaks, specified as 5.6kW for
LMR240UF.

Owen
Something happened to my cut and paste. The 1500W was supposed to refer to
the non UF.

Tam/WB2TT

"Tam/WB2TT" wrote in message
. ..

"Owen Duffy" wrote in message
...
"Tam/WB2TT" wrote in
:

BTW, the LMR240UF makes for great patch cords. It has a stranded
center conductor. 1/4 inch cable that is rated at 1500W. The LMR240

From the spec sheet, the average power rating at 30MHz is 1240W. I assume
that is with VSWR=1, so that a further derating is required for mismatch.
For example, at VSWR=2, the heating at a current maximum is nearly double
that for a flat line, so the power rating might be more like 620W with
VSWR=2.

Of course, in SSB telephony, the average power is very low and the cable
is
probably limited by voltage breakdown at peaks, specified as 5.6kW for
LMR240UF.

Owen
Something happened to my cut and paste. The 1500W was supposed to refer to
the non UF.

Tam/WB2TT

Found some Tables of loss and power handling for various cables. At 30 MHz:

LMR240 has a max power of 1490W, compared to RG213 of 1800W.
LMR240 has a loss of 1.3 DB, compared to RG213 of 1.2 DB.
Not a whole lot of difference, but the 213 has about 3X the cross section
area. The LMR240 has 90 DB shielding, the 213 is not specified.

I assume that these were specified under the same conditions. It is
interesting that at 900 MHz, the LMR240 has less loss than RG213. Compared
to RG8X, the 240 has 4 times the power handling capacity.

Tam