Vhf

There are easy instructions to build your own yagi on Instructables. I had just picked up some hose clamps and had the other necessary pieces: a broken tape measure and some 3/4-inch schedule 40 PVC and connectors; so I was ready to build.

The wiring on mine is held in place by the clamps and banana clip adapter. I always like those for prototyping. As directed, I tuned the antenna by moving radiators in and out and measuring with the NanoVNA.

The antenna is noticeably directional, so I can use it to find directions of signals. The S-meter and dB signal strength numbers on AUBS firmware make it easy to evaluate strength and direction.

I transmitted with it to the K3IR repeater as a test during a net.

I removed the magnet from the inexpensive mag-mount antenna that I had stuck to a baking sheet in the back of the BMW i3 (which is all plastic). The bike rack is always on the car, so I cobbled together some scrap metal parts and clamped the antenna onto the rack. It’s got a screw knob, so I can loosen and reorient it when I flip the bike rack.

It works great now with the antenna outside the car and attached to the metal of the rack.

The ISS passed at 8:55am EDT at 49 degrees. My vertical 1/4-wave ground plane antenna in the tree picked it up really well. I copied a handful of callsigns pretty easily:

• KO4PDI - FL
• KC4Y - AL
• K4MMD - FL
• N5ACR - MD
• KC4YMT - GA
• KC3MM - SC
• K3DMM - PA, Harrisburg

I confirmed hearing K3DMM on the Morning Grind round table (K3IR) a few minutes later that morning.

Reception Problems

During 985 net on Monday night, which is VHF on my UV-K5 running egzumer 0.22.0, I’d get periodic static in reception. It got bad enough to completely cut-out. I was using my simple wire dipole hanging in the tree outside.

K3IR had been frustratingly quiet as well, so I checked the antenna with the NanoVNA as it hung outside. There were no fluctuations in SWR, so it’s not connections or proximity.

I tried the Explorer QRZ-1 HT, and it sounded great on the same antenna on the same net. Is my UV-K5 broken?

To test a bit further, I ordered a new UV-K6 to compare. I also downgraded to egzumer 0.21.0 for further testing.

The next day, Tuesday morning, K3IR was sounding better, but I was getting the same periodic noises. The outside antenna doesn’t completely cut out, but shows terrible doubling/overload as if from FM station.

Inside, the magmount antenna on the 3d printer is better. Is the dipole outside too sensitive and bringing in more signal than the frontend of the UV-K5 can handle?