Thunderbird Hamfest 2020

I always find good deals on test equipment on the West side of town. This year’s Thunderbird Hamfest continued that streak.

I found an HP 3435A Digital Bench Voltmeter and an HP 5314A Frequency Counter at a reasonable cost (Total of $25 for the two).

They are both functional.

HP 5314A Frequency Counter
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Nano_VNA Testing

This year, one of my Christmas presents was a Nano_VNA (Vector Network Analyzer). These are like an antenna analyzer on steroids. You can check the SWR of your antenna through a range of frequencies, and get detailed information about the antenna impedance, including whether it is inductive or capacitive at a given frequency. This information is useful in developing matching networks for your homebrew antennas.

The Unit has the additional capability to inject a swept frequency range through a device and detect how much gets through the output of the device under test. So it should be great for sweeping filter networks (Low Pass, High Pass, Band Pass, Notch, etc…), as well as cavity filters used in repeaters.

The Nano_VNA covers all frequencies between 50 khz and 900 Mhz. That is a pretty good range, and covers the VLF bands, all of the HF bands, 2 meters, the 220 Mhz band and the 70 cm band.

Just to get familiar with it, I connected it to my K4HEX Hex beam, which should have resonant spots on the 20, 17, 15, 12, 10 and 6 meter bands. In addition, a friend with the same antenna told me that he uses his regularly on 2 meters with good success, so I swept that band, as well.

Nano VNA from Amazon
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Debugging ANSRTrack – Part 3

Unexplained Rotator Movement

There is one final problem noted during the inaugural flight with the new ANSRTrack Ground Station program. At a point about 30 – 45 minutes into the flight, the ground station received an APRS beacon from the balloon, on its normal 30 second interval.

The azimuth rotor suddenly rotated about 45 degrees counterclockwise from its prior position. As I looked at the screen to determine what might have happened, we received another beacon, and the azimuth control returned to where it should have been pointing. This twice. Once at about 36 minutes into the flight, and once at about 42 minutes into the flight.

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Debugging ANSRTrack Cont’

Continued Debugging effort

The next anomoly to investigate concerned the slow climb rate observed during the ANSR-122 flight. Normally, we expect about 1200 – 1300 feet per minute climb rate, but a rate of 600 fpm was observed about a half hour into the flight.

An analysis of the telemetry data from our two beacons (KA7NSR-6 and KA7NSR-7) indicate that the climb rate did indeed fall to around 600 fpm at that time in the flight.

Climb & Descent Rate for entire flight
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Debugging ANSRTrack

Tracking down some bugs

As mentioned in my previous post, there were a few anomolies when I ran the new ANSRTrack program during a live flight.

In this post, we will track down a couple of the issues:

There was a consistent error showing up at the bottom of the screen mainwindow: Update call to move rotator() failed.
This was happening consistently enough to quickly overwrite any other valid messages that should have appeared in that space.

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