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Propeller Head Plaza: RE: Check their math by tomservo

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RE: Check their math

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Hi
"I'm surprised that radio quality non-audiophile cabling doesn't provide such basic information."

Keep in mind for RF, up where specialty coax cables like these would be used, one is many many decades higher up in frequency. That high up, it is attenuation per length that counts not the lumped values seen in audio.
For example;
http://www.amsat.org/amsat/articles/houston-net/coax.html

If i recall, the coax i used was about 23pf per foot, about 6 microhenry's per foot and 1000 feet has an Rdc of about 1.2 Ohms and 1.1 Ohms (inner and outer).
The important thing is the values of the secondary elements relative to the change they can make within the circuit.
The problem i had was the cable was 125 feet long, not 20 feet like in a living room so the L, R and C had to be small, like a short cable.

"I guess I would wonder how such actually works with real world amplifiers as a system."

I have a pair of coax loudspeaker cables that i use ocasionally, for a long time they were sitting side by side with the normal cables. I couldn't hear any difference but when i re-arranged my room, one coax was too short so i took them up.

If your interested in try this approach, locate a Hamfest in your area and keep a few of the wire names in mind.
Belden 9913
LMR400
Also these have a stranded core and are more flexible.
Belden 9913F
LMR400 ultraflex.
Hamfest's are a great place to troll for stuff, i bought a hundred feet of low loss coax for 16$ for example.
I wouldn't be too picky, compared to generic speaker cable any of these high performance RG-8 off spring have much smaller secondary elements.
Best,
Tom Danley




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