Just as a point of interest depending on who makes the coax completely
different dielectrics are possible with extremely wide spanning power
ratings and other specs.
For example there is a RG-179 cable available in Europe with a standard
PE dielectric and 0.66 VF vs the traditional PFTE.
https://docs-emea.rs-online.com/webdocs/0624/0900766b8062495d.pdf
And Belden's version, while PFTE with a power rating of 1250 watts at
6m, is radically different from the similar PFTE coax from Habia (which
is known for excellent cables). Here the power rating is very
significantly lower.
http://www.militarysystems-tech.com/files/militarysystems/supplier_docs/RG%20Coaxials.pdf
It suggests to me you best find the exact specs from the maker of the
cable you plan to use. No "one brands RG-xx specs will be pretty much
the same as another makers same RG-xx cable".
Also one company may rate there power capacity as an average power under
some specific tolerances (temperature rise, impedance change, etc, etc)
while another company may rate power a completely different like peak
using different parameters all together.
Gedas, W8BYA
Gallery at http://w8bya.com
Light travels faster than sound....
This is why some people appear bright until you hear them speak.
On 1/24/2019 8:38 AM, john@kk9a.com wrote:
I use RG302/U for 75 ohm chokes.
John KK9A
Jim Brown K9YC wrote:
Thanks Grant. In a quick search, I found RG179 on Pasternak's website,
but didn't see a relevant power rating at HF. Looking at Belden's
datasheet, VF is 0.695, so a bit more shortening of the feedline will be
required as compared to LMR200-75.
73, Jim K9YC
On 1/23/2019 4:48 PM, Grant Saviers wrote:
Another coax choice for 75 ohms is RG179, TFE + SCCS conductor +
silver shield. Slightly less diameter than RG400. I've not had SCCS
creep problems in dozens of QRO chokes I've made with 50 ohm SCCS
RG142, but if buying new 50 ohm cable the stranded RG400 is the better
choice. Belden says 1250 watts at 50MHz for the 75 ohm RG179, so for a
160m or 80m 4 sq probably has lots of headroom. 179 is available on ebay.
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