#50 OHM HARDLINE COAX TV#

I seem to keep running into issues finding connectors/patch cables/adapters (see other threads) and it all seems to revolve around ohms. My antenna is a 20-176 with a PL-259 and my scanner is a BR330T with an SMA.

#50 OHM HARDLINE COAX TV#

My coax is 75ohm (former sattelite TV cable). Have fun! It is a great hobby, and you will be surprised what you can receive with very little.As I research my new scanner and antenna connection I seem to keep bumping into the 'ohm' issue. If you really want to TX, then I would suggest to design/build an antenna for this with known components in order to avoid damage to your transmitter. You do mention 'may transmit', and just a word of caution here. Then if you want to squeeze every single micro-dB out of your antenna system, then you can look at different materials/components, and budget for such.Īnd even when you calculate all this upfront, the moment you hang it outside in a tree or near a building, over real ground, the calculations may be off. the succes rate is determined on what you hear, not what is calculated upfront. Have I used a TV-balun with TV-coax and a OCFD ? - no, I have no practical or qualified response to that.Īs an SWL, work with the materials you have, work with what can be got cheaply, experiment, direct feed your OCFD, use the TV-balun. Have I used 'some coax' ? - yes I have, with various succes, sometimes it was just deaf. Have I used TV-baluns ? - yes I have, with various succes, pulled it down, swap in/out, try again watch your walletįor antennas I have used from rain gutters to water pipes, as feedline I have used from TV-coax to speaker-wire. rule 3: it is a hobby in which you can go mad.rule 2: any feedline is better than no feedline.rule 1: any antenna is better than no antenna.And I have used unspecified components and material to build a range of antenna's. However, I did started off in this hobby as a SWL. Without knowing the very specifics of the TV-balun, and TV-coax, it would be hard for anyone to come up with a qualified or quantified answer for your particular question. Unknown is also the quality and specifications of the 'TV coax' you are planning of using.Īs you are starting, and as you are only listening (no TX), I would actually fully agree with the answer given by Mike Waters unqualified or not. The unknowns here is the suggested balun, and its behaviour when used with the OCFD. Even when you change over to a 50-Ohm receiver the loss due to mismatch is negligible. However, you are using an RTL-SDR dongle with a source impedance of 75 ohm, and your feedline is 75 ohm, you use a proper 4:1 balun for a 300 ohm antenna, then you should be good to go. I doubt that you would actually notice this.

If you have a 50 Ohm receiver, and connect a perfectly (Z=R) 75 ohm antenna system, then your VSWR would be 1.5, and the 'load mismatch attenuation' will be about 0.177dB. OK, let me try to answer this, but this answer may also be qualified as unqualified. So I'm not concerned about lightning/rain/snow/wind. Oh and it wouldn't be strung up 24x7, just when I wanted to go listen then taken down the rest of the time. I may transmit, but that would not be a priority. Would be cool to pick up overseas as well, but that may be wishful thinking. But I'm not going for excellent performance, just want to be able to listen to some of the transmissions in my region. And the RTL-SDR already has a 75 ohm input, so there's that. I am aware that using 75 ohm line on a 50 ohm Pixie will result in at least a 1.5:1 SWR, if not higher. And 25 feet is about the max height I can get by slinging up in the trees around my house. Per this page when an OCFD is 20-25 feet above ground I should use a 4:1 balun, which matches the 75-300 ratio, if I am not mistaken. (Probably would build two antennas, one for each radio.) I already have a 75-300 ohm TV balun and lots of CATV coax. Want to do lots of listening on both my RTL-SDR and Pixie 2 40M QRP kit. Just getting started and not a lot of cash. And as for the coax length, probably no more than 20 feet. If I could listen to 10% of transmitters within a 100 mile radius that would be acceptable. Can I use TV coax and a cheap TV balun to build a poor-man's OCFD? Marginal performance is acceptable if it saves money.

50 ohm hardline coax