Part of the discombobbled nature of this RG6 discourse might have to do with a lack of detail on failure modes, dissipation, etc.
With a long run, say 200 feet, running 1.5 K, and let's say dissipating 400 watts, that would be dissipating two watts per foot, or 0.17 watts per inch. If you placed your thumb and forefinger around that one inch somewhere, in an outdoor setting you could not detect 0.2 watts worth of additional temperature. The energy dissipation level of .025 watts per square centimeter is just too far down. That amount of power is clearly not destructive, either. BUT, do you want to lose 400 watts? So the question, as always, is "Would you tolerate that inefficiency in your amplifier?" If your Alpha 9500 would only put out 1100 watts, you would have a conniption fit with the folks in Colorado. And then run RG6 out to your antenna? Does the word schizophrenia come to mind? The only other similar subject where our power aims seem this schizophrenic is our inattention to 160m ground current losses on vertical radiator antennas. Burning up the RG6 is not the issue if it's run to a decent match at the antenna. It's the LOSS. Most of that stuff has a copperweld center conductor for strength, and an aluminum foil primary shield and the copper is economically very thin as all of it was designed for VHF/UHF/SAT use, copper just barely thick enough for VHF. On 160, skin effect is in the steel. Then there's the aluminum foil. Hams are an invisible microscopic portion of their customer base, and we don't count for dink in their business model. RG6 is cheep because they make thousands of miles of the stuff in bulk for VHF/UHF/SAT, very carefully engineered specifically for VHF/UHF/SAT. I'm sure that we could get all copper center conductor with copper foil and copper woven shield. But then it's not cheep any more. I'm not surprised that F connectors can carry QRO, because BNC connectors can. It only has to carry four and a half amps at 75 ohms QRO, even less for split feeds to phased antennas. After all basically an N connector is a BNC with weather proofing. The question here is what happens when the connector goes bad. Is there enough contact area that it takes its time, or does the sudden resistance with a very small contact area go up in smoke. That's why I stick with teflon/silver UHF connectors on HF. A lot more staying power. And then there's the argument that since I run 100 watts or QRP, it doesn't matter. Except the loss has a far more harsh effect on QSO rate as the power level goes down. Truth be known, it's the QRP operator that needs the hard line, that needs the commercial BC radial field, for whom it will make the most difference. Got nothing at all to do with burning stuff up. 73, Guy. On Tue, Oct 18, 2011 at 1:40 AM, Robert Smits <[email protected]> wrote: > On Saturday 15 October 2011 07:47:01 John K9UWA wrote: > > That would have been me Dave. I have been using Garden Variety RG6 > > on my 160 array for well over 20 years. I tested a single run of it with > a > > pair of heathkit dummy loads. Test piece of cable was 10 feet long with F > > connectors to F-UHF adapters. Brick on the KEY on the Amp until the Dummy > > loads started to smoke. Amp off and grabbed the coax. No heating observed > > in the coax or the F connectors. > > > > And how do you get it back down to 50 ohms for the transmitter. > > > > -- > Robert Smits [email protected] > _______________________________________________ > UR RST IS ... ... ..9 QSB QSB - hw? BK > _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
