Vhf on John Flinchbaugh KD3EE

6M Opening

Mon, 21 Jul 2025 00:00:00 +0000

I saw an opening on 6M just now. I was getting contacts an my 71-foot random wire at home about 1000 miles away: Florida and the midwest. 10M is looking similar, even though the MUF map says only up to 21MHz should work. 15M is getting to Southwest, but it’s mostly like 10M. Later in the day, around 2pm local, 6M is open to Wisconsin more than Florida.

Fixing the De-tuned Slim Jim

Tue, 25 Mar 2025 00:00:00 +0000

The slim jim I put up for APRS was hanging right next to the feed line of the higher quarter-wave antenna I use for local analog traffic. The feed line was de-tuning the slim jim, so reception of APRS traffic was almost non-existent. I could swap the antennas and the higher one worked much better, and the lower slim jim was greatly degraded for other FM traffic. Usually the BTech is on the lower slim jim, and the Quansheng is scanning on the higher quarter-wave.

To correct the problem, I pulled the 2 antennas up on separate ropes and separated them by a couple feet. The quarter-wave is still mounted higher than the slim jim.

Newly-Tuned Slim Jim

Tue, 25 Feb 2025 00:00:00 +0000

I launched the newly-tuned slim-jim antenna. With it hanging from the fan, it looked tuned. Hanging right next to the siding outside the window, it looked long.

I launched it into the tree to hang right below the quarter-wave. Hanging in the tree, it looks well-tuned. I compared both antennas simultaneously with the 2 Quanshengs, and the lower slim jim measures 10-20dBm lower than the higher quarter-wave when receiving.

Antenna Maintenance

Sun, 29 Dec 2024 00:00:00 +0000

The 1/4-wave ground plane antenna in the tree dropped its feedline, so I brought it down to reattach it and resolder the radials.

I also walked down the yagi on the pole to straighten some elements, since it was a nice day. The yagi was spinning around in the wind, so I also changed the way it’s mounted to clamp it more securely.

I also added some reigns to the mast, so I can (try to) spin it from inside the window. It works well some times but not others. The pole can freeze to the ground.

Talkaround

Sun, 08 Dec 2024 00:00:00 +0000

Listening to KX3B, I occasionally learn something. Some radios have a button or menu to do away with the offset on a repeater, so you can talk simplex on the output frequency when out of range of the repeater.

I’ve done this by accident.

Antenna Maintenance

Fri, 22 Nov 2024 00:00:00 +0000

The home-brew yagi blows around in the wind a bit, so I brought it down this morning as it started to snow, so I could straighten and tighten the elements. I realigned it for the 985 repeater, and checked it to be giving -96dBm.

I also resoldered some radials on the 1/4-wave ground plane antenna that go knocked loose in the tree.

flag pole mast

straightened yagi

Bug with TYT TH-9800

Mon, 28 Oct 2024 00:00:00 +0000

I can set a repeater offset from Chirp, and that works fine, but it displays incorrectly in the SHIFT setting on the radio. It displays as 7.60MHz for every repeater frequency. Apparently, visiting the setting in the menus gets the really bad value (7.6MHz) applied until you leave the channel and come back.

Reversing the repeater frequencies (assigned to P1 on the microphone) shows the right frequencies. Programming it from Chirp as a split (instead of +/- offset) works, but still doesn’t show correctly in the menus.

The radio also only allows setting by 10kHz manually, so setting my 605kHz shift for W3GMS is impossible to program from the radio.

There’s already a bug filed for Chirp.

Tape Measure Yagi

Sun, 16 Jun 2024 00:00:00 +0000

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.

Antenna on the Car

Fri, 07 Jun 2024 22:45:48 -0400

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.

ISS Repeater

Mon, 29 Apr 2024 00:00:00 +0000

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.

VHF Reception

Tue, 19 Mar 2024 00:00:00 +0000

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?