After my very successful SOTA activation of San Pedro Mountain the previous weekend, and the San Francisco Radio Club Angel Island expedition at the same time, the club decided to do another SOTA activation on Saturday November 14th. Antonis AA6PP, Jeff KK6JJZ, Rick K6TOR, David KN6HFV, and myself went up to the top of Mt. Davidson and activated the peak under the club's callsign W6PW.

It was a beautiful day, very clear after the rains the previous evening. We had a total of five stations. Antonis AA6PP and Jeff KK6JJZ ran the HF voice stations, trading off on 40, 20, and 15 meters during our activation. Rick K6TOR ran HF CW, and Dave KN6HFV ran the UHF station on 445.525 MHz with his HT and an Elk Antennas 5-element log periodic antenna.

Here is Antonis AA6PP running one of the HF SSB stations with an Elecraft KX2 transciever, AX1 multi-band whip antenna, powered from a Bioenno 4.5 Ah LiFePO4 battery. Notice the antenna counterpoise on the ground, stretched out in front of him.

I was using the same ...

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Summits on the Air (SOTA) combines two of my favorite pastimes, amateur radio and hiking. The objective is to climb to a nearby peak, then contact as many people as you can on the radio. While most SOTA peak activations are on HF, my only portable gear at the moment is a few HTs.

On Saturday Nov 7th, I activated San Pedro Mountain, which is 1058 ft tall. It's located in Harry A. Barbier Memorial Park in the hills above San Rafael, next to China Camp State Park.

I took the Knight Dr route, from Tom AI6CU, hiking along the Ridge Fire Road. The hike up took about 45 minutes, and some sections of the trail were very steep. I arrived on top about 12:30pm, ate a quick sandwich, and cooled off.

The radio equipment I was using was a 3-element Arrow II yagi antenna, and my trusty Icom IC-T7H handheld transceiver. RF output was about 1 watt, and the gain of the antenna was about 5 dB. Unfortunately, I only had a metal broomstick to hold the yagi ...

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The SF-HAB group got together in the beginning of August to do another high-altitude balloon launch. The purpose was to test out a new 3D GoPro camera to see how well it would perform at altitude. We also had a LoRA transciever onboard, which we are thinking about using as a remote cutdown device that we would fly on future launches.

The jet stream in July was really unsettled, so we delayed for a few weeks while the winds picked up a bit and shifted heading. Watching the predictions from HABHUB gave us a good idea when to launch. This was one of our predictions before launch.

Unfortunately, I really goofed up when doing the launch predictions. As you can see in the above screenshot, I used the default ascent rate of 3.5 m/s, which is about 680 ft/min. We normally target 1000 ft/min, so this prediction has the balloon going much further than what we were looking for.

I realized my mistake and ran some more predictions, plus the winds changed slightly overnight, so we ...

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After the success of the KD4STH launch in September, we decided to do it again! A new group formed for San Francisco High Altitude Balloons (SF-HAB), and we started scheming. The hardware and time stars finally aligned on Sunday March 8th, and we decided to launch from the Berkeley Marina. Unbeknownst to us, this was only a few days before the whole world shut down due to COVID-19. Great timing!

The balloon was a Kaymont 3kg balloon, and we used an entire K-sized tank of hydrogen for lift. Unlike some previous launches, we didn't use weights to carefully measure/specify the ascent rate, we just used the whole tank. During the chase, we calculated our ascent rate at about 1400 ft/min, which was faster than our target of 1000 ft/min. Faster ascent means the balloon is not being pushed around by the wind as much, but it will burst at a lower altitude if the balloon is overfilled. Since this was a 3kg balloon, it was not overfilled.

The primary mission of this launch was to fly a ...

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