Unchained Preppers
Communications => Radio => Topic started by: pkveazey on January 21, 2023, 12:35:18 PM
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Say What? I thought I knew everything about Radios. After all the years that I spent reading everything I could get my hands on and thinking that there wasn't much left to learn, I watched a You Tube Video about a month ago and actually learned something that I always wondered about. OK, I knew that if you don't have any high quality 50 Ohm Coax, you can get by just fine with 75 Ohm Coax but the Standing Wave Ratio will be a about 1.5:1 to maybe as much as 1.7:1 when connected to a resonant antenna. Here is what I learned. Just about every receiver on the planet usues 75 Ohm Coax and just about every transmitter uses 50 Ohm Coax. Well Here is what I learned...... 75 Ohm Coax has less signal loss on receive and 50 Ohm Coax has less signal loss on Transmit. OK, OK, I read all that I could about winding Toroid Transformers and not one bit of it sunk in. Well, I don't use Toroids anyway so I really don't care. Well, to get back to my point about 50 Ohm vs 75 Ohm Coax. I've mentioned something in a previous post about it being just fine to use 75 Ohm Coax if you don't have any 50 Ohm Coax. Years ago, I got about 200 feet of 75 Ohm Cable TV Hardline and used it on my 160 meter Dipole for years. Then one day I had some money burning a hole in my pocket and decided to buy some LMR400 equivilant to replace the Hardline. I can't tell the diference between them. Since I use an LDG autotuner, I don't think the radio gives a crap what coax I use as long as its low loss Coax. When I got into Ham Radio, Most Hams had separate world war 2 Receivers and Transmitters and used 2 antennas. I've often wondered if they used 75 Ohm on the receiver and 50 Ohm on the transmitter. Well those days are over so I don't think it matters now. The reason I'm mentioning this now is because several years ago I bought 3 spools of 100% shielded coax for $50 and I don't know if they are 50 Ohm or not. I short ciruited one end of one spool and connected an anylizer on the other end and the smith chart said it was about 60 ohms. Hmmmm. I think I can use that stuff for just about anything I want. When the SHTF, I won't hesitate to use it for VHF/UHF home brew outdoor antennas for members of my MAG.
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:thumbsUp: :cheers: Pkv.