50 ohm vs 75 ohm......
Good Morning, "Mr.", All,
As long as you aren't transmitting or even if you are, there is just a slight difference in the 50 to 75 ohm coax. On a receiver, this is not that big a deal. However, if you are using it to transmit on, with a transistorized or surface-mount IC transmitter, the vertical standing wave ratio (the difference in "match" between the radio, coax, and antenna, is probably too great to use. On a tube-type transceiver, it's about 1.5 : 1 and acceptable. New transcievers don't tollerate that much of a mis-match.
Now, since you are using it for a scanner receiver, there's not that much noticable difference. Here on my scanner antennas from the antennas to the receiver, I use quad-shielded, RG-6, up to 150 mhz. Above that, I use TV, RG-11 Underground for less loss at longer lengths and heights. IF I had access to 1/2" to 3/4" hardline, I'd use it for UHF antennas, with adapters to use the last 6' being TV RG-11.
IF you can find the RG-6 from a supplier for Cable TV coax, get the one that has the "messenger wire", a covered aluminum wire that enables you to string long spans with the aluminum wire for support. This is usually used as a "drop wire" from the pole to the house. Leave enough "wire" to secure it to the antenna mount to hold the vertical wire straight, leave a "drip loop" near the antenna and use stand-offs to keep it away from the metal support pole. Then, make another "drip loop", at a "ground block" and bring the coax in the house.
When I get it finished, I'm adding a "primer" on antennas. coax and etc for "tips". I don't consider myself an "eggspurt" by any means. Just what I've learned over 50 years of Radio/Electronics, LOL!
If you have "questions", I can be emailed or "e-mauled" (flamed) at:
KA5(dot)LQJ(at)gmail(dot)com. <== to keep SPAM bots away, LOL!
Respectfully submitted,
73 (Best Regard)
Don/KA5-LQJ