Which is it, RG59 or RG6?
in [Repair]
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From: Jeff Liebermann on 6 Dec 2009 23:49 On Sun, 06 Dec 2009 22:51:17 -0500, "Michael A. Terrell" <mike.terrell(a)earthlink.net> wrote: > Part of the extra .5 dB loss is in the cast aluminum 'F' connectors. >I ran Q. A. I ran tests on hundreds of samples to qualify them for our >MSO to purchase the best quality we could find. We bought splitters by >the thousands, and coax by the pallet > > Also, eight way splitters are listed at -10 dB, not 10.5. Agreed. However, I never had much trouble with the aluminium F connectors. It was the chrome plated zinc castings that drove me nuts. The RF skin depth at 1GHz was terrible making the connectors rather lossy. Combined with an aluminum F connector, I had a few millivolts of electrolysis and noise. For entertainment, I like to string all the adapters in my collection in series, and measure the loss. According to numerous luminaries, the attenuation would be attrocious, sky high, dismal, or anything except nominal. I don't have photos of my last song and dance in front of the local radio clubs, but one person agreed to reproduce the experiment with decent test equipment: <http://802.11junk.com/jeffl/antennas/connector-loss/> The display photos are rather difficult to read. The loss through about 20 adapters is about -0.3dB at 450MHz and -2.0dB at 2.4GHz. That's approximately the loss of an equivalent length of LMR-240. I've done similar tests with assorted F adapters with similar results. The chain a created for the local radio clubs was about 6ft long. I got lazy and just used a wattmeter at each end of the coax, and a handheld radio. Hardly any loss at 446MHz. -- Jeff Liebermann jeffl(a)cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
From: Jeff Liebermann on 7 Dec 2009 02:35 On Sun, 06 Dec 2009 23:11:22 -0500, "Michael A. Terrell" <mike.terrell(a)earthlink.net> wrote: >Ingression is external signals getting into the CATV plant. You are >describing radiation' where the signal is lost to being radiated from >the outer conductor, due to poor connections. It is monitored on a >continuous basis on most cable systems using 'Sniffer' or other brands >of monitoring equipment. While the signal is on the video carrier >frequency, it is FM modulated with annoying audio to make it easy to >identify. Well, the leak or ingress goes both ways. While ingress from ham, commercial, and broadcast radio xmitters are irritating, the regulatory requirement is to prevent cable leakage from interfering with public safety, aircraft, and of course, OTA broadcast. Lots of nice toys to measure this leakage: <http://www.trilithic.com/Broadband%20Instruments> >> Personally, I prefer visual inspection, a TDR (time domain >> reflectometer), signal level measurements, or just a pre-emptive >> replacement. > Those are OK if you can shut a system down for repairs. Poor >connections in the trunkline can be detected by reading the voltage drop >between the coax and the amplifier housing, splice block or any other >splice in any powered cable. 60 volts modified sine wave AC @ 30 amps >from a CVT doesn't tolerate much resistance without causing hum >modulation or burning up a connector. Ummm... the OP is trying to troubleshoot his home installation, not the trunk line (or cable drop). I think it's a safe bet that he can unplug his spaghetti without difficulties. -- Jeff Liebermann jeffl(a)cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
From: Michael A. Terrell on 7 Dec 2009 02:59 Jeff Liebermann wrote: > > On Sun, 06 Dec 2009 22:51:17 -0500, "Michael A. Terrell" > <mike.terrell(a)earthlink.net> wrote: > > > Part of the extra .5 dB loss is in the cast aluminum 'F' connectors. > >I ran Q. A. I ran tests on hundreds of samples to qualify them for our > >MSO to purchase the best quality we could find. We bought splitters by > >the thousands, and coax by the pallet > > > > Also, eight way splitters are listed at -10 dB, not 10.5. > > Agreed. However, I never had much trouble with the aluminium F > connectors. It was the chrome plated zinc castings that drove me > nuts. The RF skin depth at 1GHz was terrible making the connectors > rather lossy. Combined with an aluminum F connector, I had a few > millivolts of electrolysis and noise. the tap plates were cast aluminum if they were Jerrold, or plated brass threads bolted to an aluminum plate in Lindsay taps. Both cause problems in areas where road salt was used. Just as bad were the unplated brass cable connectors someone tried to sell us. > For entertainment, I like to string all the adapters in my collection > in series, and measure the loss. According to numerous luminaries, > the attenuation would be attrocious, sky high, dismal, or anything > except nominal. I don't have photos of my last song and dance in > front of the local radio clubs, but one person agreed to reproduce the > experiment with decent test equipment: > <http://802.11junk.com/jeffl/antennas/connector-loss/> Run the tests again after a 48 hour salt spray test. > The display photos are rather difficult to read. The loss through > about 20 adapters is about -0.3dB at 450MHz and -2.0dB at 2.4GHz. > That's approximately the loss of an equivalent length of LMR-240. I've > done similar tests with assorted F adapters with similar results. The > chain a created for the local radio clubs was about 6ft long. I got > lazy and just used a wattmeter at each end of the coax, and a handheld > radio. Hardly any loss at 446MHz. -- Offworld checks no longer accepted!
From: Jeff Liebermann on 7 Dec 2009 12:34 On Mon, 07 Dec 2009 02:59:30 -0500, "Michael A. Terrell" <mike.terrell(a)earthlink.net> wrote: > the tap plates were cast aluminum if they were Jerrold, or plated >brass threads bolted to an aluminum plate in Lindsay taps. Both cause >problems in areas where road salt was used. Just as bad were the >unplated brass cable connectors someone tried to sell us. Again, this is for outdoor use. The OP is doing indoor. >> <http://802.11junk.com/jeffl/antennas/connector-loss/> > Run the tests again after a 48 hour salt spray test. <http://en.wikipedia.org/wiki/Salt_spray_test> Actually, I have. I used to design marine radios and the salt fog test was one of the hazards of the business. None of the equipment survived 100%. We were just checking for problems that might occur in a marine atmosphere. As I recall, the silver plated brass connectors did quite well, while the cadmium plated pot metal died a horrible death. Dissimilar metals and connector materials were also bad. Unless you watch TV in the shower, I don't think any of these will be a problem with an indoor installation. -- Jeff Liebermann jeffl(a)cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
From: mm on 7 Dec 2009 13:15
On Sun, 06 Dec 2009 20:49:12 -0800, Jeff Liebermann <jeffl(a)cruzio.com> wrote: >On Sun, 06 Dec 2009 22:51:17 -0500, "Michael A. Terrell" ><mike.terrell(a)earthlink.net> wrote: > >> Part of the extra .5 dB loss is in the cast aluminum 'F' connectors. >>I ran Q. A. I ran tests on hundreds of samples to qualify them for our >>MSO to purchase the best quality we could find. We bought splitters by >>the thousands, and coax by the pallet >> >> Also, eight way splitters are listed at -10 dB, not 10.5. > >Agreed. However, I never had much trouble with the aluminium F >connectors. It was the chrome plated zinc castings that drove me >nuts. The RF skin depth at 1GHz was terrible making the connectors >rather lossy. Combined with an aluminum F connector, I had a few >millivolts of electrolysis and noise. So is there any value in getting gold-plated F connectors (if they have them) or gold-plated A/B switches (which I know they sell)? It's the A/B switch I'm particularly curious about because at one store, that was all they had, and some antenna signals are so weak, I figured any little thing might help. Or other gold plated connectors? |