The TV splitters to connect two TV's to the same antenna are very cheap and work just fine at that frequency.? ? They are a simple transformer, they have no impedance of their own.? So splitting 75 Ohms or 50 Ohms is no difference.? ? Don't like the PAL or F connectors, take out the little transformer and put it in your own box.? Kent
toggle quoted message
Show quoted text
On Wednesday, May 4, 2022, 10:07:30 AM CDT, Torbj?rn Toreson <torbjorn.toreson@...> wrote:
Hello,
I intend to use the same antenna for two RX-radios. I will lose 3 dB, but for the sake of the radios RX-input I intended to present each with roughly 50 ohms.
The frequency is about 90 MHz (not HAM-use). I made two 1/4 wave transformers with RG59 coax, taking VF of 0,66 in consideration.? Measuring each one with the Nano and 50 on the outer side I get as anticipated about 110 ohm. Now the idea is to parallell the two 110 ohm sides and get around 55 ohm, this is where the antenna should be connected. Imagine the cable-setup as a V, with the vertex (bottom on the V) labeled A and the two upper parts labeled B and C.
When I connect 50 ohm dummies to B and C then I can measure about 50 ohm at A for 90 MHz. Now I wanted to see what one of the radios would feel so I connected 50 ohm dummies (actually 50 ohm pieces from calibration kits) at A and C. Now measuring at B I was expecting to see about 50 ohm. That was not the case, the result was about 140 ohm (X about 0) and? SWR about 3 (of course). At about 150 MHz I got a SWR minimum.
Please help me to understand why the setup works one way (as e.g. to connect two phased antennas) but not the other way to connect one antenna to two radios.
73/Torbjorn/SM6AYM
