Just experienced my first major tropospheric ducting on 2 meters and 70 centimeters this morning. Wow!

Tropo March 2016 144
Courtesy DXMAPS.com

Tropo Opening

Woke up at 5:30 AM and turned my IC-910H to 144.200 MHz. Heard some stations making noise and started working not only new grids but new states. By the time the band went quiet five hours later, I’d worked 5 new states and 13 new grids on 2 meters along with 4 new states and 10 new grids on 70 centimeters.

Grids and States

For 2 meters, that nearly doubled my grid count and added Louisiana, Alabama, Georgia, Mississippi, and Florida to the state count. For 70 centimeters I tripled my grid count and added Alabama, Georgia, Mississippi, and Florida. Nearly all the signals were booming in with just a few somewhat weak. Not bad either for my WA5JVB cheap yagis at 25 feet.

Tropo 432 March 2016
Courtesy DXMAPS.com

You can see the DX Maps snapshots nearby. The top map is for 2 meters and the bottom map for 70 cm. Click on the images to see the detail (and my call sign…).

I feel the bands were open far longer than we thought. We just ran out of people that we hadn’t already worked.

IC-910H Prep Work

The good news was that I was prepared for this opening. I had measured the output power of the 910H and found only 50 watts on 2 meters and 40 watts on 70 cm. I shipped it off to Matt Adrian, KD8ZB, the consummate Icom repair guy.

He reported the power was just fine. Hmmm, does that mean my power measuring gear is off? I had also sent along an Icom CR-293 high stability oscillator, which he installed. He also calibrated the output frequency. That should help with meteor scatter schedules.

Measuring Power at VHF/UHF

Early in my work with the IC-910H and VHF/UHF I had purchased a Red Dot power meter. It worked really well in measuring SWR but I was only seeing roughly 50 watts. So I needed to get a dummy load that worked at VHF/UHF to make sure the rig wasn’t responding to SWR and pulling back the power level.

In the process of looking for that, I came across a great bargain on a Bird 6154 Termaline wattmeter with built-in dummy load, good to 1 GHz. It measured the same amount, 50 watts. That’s why I shipped it all to Matt.

Power Input vs. Power Output

Once it was back, I continued to scratch my head. Mostly I suspected the power meters. Once I got over that narrow thinking, I looked at the DC power going to the IC-910H. Bingo! While the power supply, Astron RS-35, was old. It was putting out 13.8 VDC. But at the rig I was measuring 11.5 VDC. Rebuilt with 10 GA wire and greatly shortening the power cable resulted in 12.8 VDC at the rig. This brought the power output to 100 watts on 2 meters and 75 watts on 70 cm.

It’s amazing how these things work and how long it can take me to figure out these things.

Fun Times at K5ND

I’m really enjoying VHF/UHF weak signal work and this morning was a blast. Thanks to everyone who worked me and those who put up with my inadvertently QSYing on top of them…

Yet another part of my ham radio adventures.



What do you think?