Does COAX Quality Affect Your EFHW Antenna? The Unexpected Result!

[@MidlifeRenaissanceMan]

I’m cheap. I have LMR400 but I use RG58CU for the most part…with BNC connectors. Usually running 20W occasionally a dollar, but never much over that I have made my own with solder BNCs that have a flexible moisture seal. 5m 7.5m 10m and 15m depending on the antenna arrangements. They deliver. I also purchased some pre made 10m cables. They say they’re RG58CU and have a BNC with a strain relief, however, I have been getting some strange results. When I put a Nano VNA on them and read the SWR and log mag between the S21 and S22 ports, I see the SWR bounce between. 1.15:1 and 2:1 along with a dB or 2 of loss. It’s weird. I noticed something was up when I was tuning up a mag loop. Warrants further investigations. 73 de VK2NAP dit dit

[@aa3konthego]

Have you tried flexing the cable at the connectors and along its length? You may need someone to help you.

[@survivalcomms]

Anything between the output and the elements including the transformer matters. SWR in and of itself isn't the performance indicator that folks make it out to be. Put a 1 or 2 db attenuator inline and you can see the SWR decreases in most cases but the loss is increased beyond the loss incurred by the original match inefficiency. 3:1 SWR is 25% loss 2db of system loss is just a tad under 40% loss. Using good cable is good operating practice. Thanks for sharing !

[@aa3konthego]

You are correct in that adding some loss to the feedline, you can make a poor match look good. I'm sure some shady commercial antennas have done this.

[@survivalcomms]

@@aa3konthego Indeed they have. They do have an impressive marketing machine however :)

[@Slade677]

Good video. I tried M&P for the first time recently. It's fine, but not better than the RG8X I've been using for years from DX Engineering. In fact, M&P was only coax I've ever had that a twist tie tore the jacket. I'll stick with the RG8X.

[@aa3konthego]

Interesting observation. Was it POTA-Flex 6 or 7? They make several versions of 50 Ohm coax and not all have the same jacket material.

[@m7trsradio]

Great video. I use RG8X. About 6m with my efhw when portable. Great coax but a pain if it gets tangled lol. 73

[@aa3konthego]

@@m7trsradio I roll mine out and up by hand so there is no twist which could do damage to the internals. Less stiff than the POTA-Flex. Now if you want tangled coax, try RG-174! Really soft and floppy. Thank you for watching!

[@russellhayes911]

Great information. Thanks for posting. 73 KE4GTQ

[@aa3konthego]

You're welcome! Thank you for watching.