Field Day 2017

Setting up for landing on runway 35 at KTIW

Just like last year, the weather was absolutely great for field day this year. I was lucky enough to be high up in the air this year and worked a lot of stations on 146.52 and 146.55 FM. Thanks to everyone who was patient in the pile-up. It’s tricky to do this in the air when there are so many stations that can hear you, but not each other.

VFR Flight from KMMV to KTIW (Direct Flight Path). Cruise altitude 10,500 ft.

Confirmed Contacts

Call sign, Location

  1. Operating as N1QQ, 1C/OR
  2. KF7UOQ
  3. KC7TAK, Beaver Creek, OR
  4. KK7PR, Bald Peak, OR
  5. N7DB, Sandy, OR
  6. KG7FOP, Sheridan Peak, OR
  7. KK4IBO, I-5 Northbound Exit 21
  8. W7HRY, Silver Star Mountain, WA
  9. WA7ASF, Troutdale, OR
  10. W7PRA, Corvallis, OR (100+ miles)
  11. KI7FCI, Vernonia, OR
  12. WA7LK, Enumclaw, WA
  13. K7KID, Naselle, WA
  14. K7BPH, Brush Prairie, WA + (op. KG7IED)
  15. AE7ZC, Beaverton, OR
  16. KC7VH, Southeast Portland, OR
  17. K7BH, Vancouver, WA
  18. Crossed Washington-Oregon Boarder, Hereafter Operating as N1QQ, 1C/WWA
  19. KK7PR
  20. KF7VWA, Woodland, WA
  21. W7PIG, Camano Island, WA (150+ miles)
  22. W7RC, Ridgefield, WA
  23. KA7AUY, Salem, OR
  24. WA7AIA,
  25. KG7SJY, 5 miles N. of Battleground, WA
  26. KG7RQJ, Coupeville, WA (150+ miles)
  27. VE7VVC, Vancouver, British Columbia, Canada (225+ miles)
  28. W0MUD, Astoria, OR
  29. WB7OSC, E. of Amboy, WA in the Gifford Pinchot Nat. Forest
  30. N7RIG
  31. KI7F
  32. KI7DFG, Montesano, WA
  33. KF7HQR, Enumclaw, WA
  34. K7SMA, Northeast Portland, OR
  35. N7KE, Redmond, WA
  36. AC7CL, Silverdale, WA
  37. NE7NE, Shelton, WA
  38. K7EZI, Port Ludlow, WA
  39. KC7IGT, Renton, WA
  40. K7LED, Marrowstone Island, WA
  41. KB7NMU, Yelm, WA
  42. AD7BF, Everett, WA

Happy Field Day 2016

Happy field day from Seattle! Unfortunately my schedule has been very busy lately, and prevented me from doing anything particularly exciting for field day this year, but I did get the chance to operate for a little while from Kerry Park in Seattle. It was a beautiful day to be outside, as you can see below.

Field Day from Kerry Park
Field Day from Kerry Park

Weather Station and the Raspberry Pi

USB to RS-485 Adapter
USB to RS-485 Adapter

One of the weaknesses with my weather stations was that they did not have the ability to accept incoming connections. This made remote debug a bit difficult, if not impossible. Basically, you program the thing, and hope there are no glitches. Surprisingly, this worked for many years with the occasional reset, but I finally decided to spend some time making some improvements to this aspect of the weather station system.

Originally, my weather stations consisted of an outdoor unit, which acted as a hub for all the outdoor sensors. The hub communicated with an RS-485 to Ethernet bridge (Arduino+Ethernet shield) inside the house near the router. This allowed long runs, and the ability to easily chain multiple hubs together on the RS-485 bus. I decided to keep the RS-485 bus model, and built a USB to RS-485 bridge to replace the Arduino and Ethernet shield that I used previously. The new USB adapter uses an FTDI chip and is compatible with most Mac, Linux, and Windows computers out-of-the-box. I was really happy to avoid the use of drivers. This adapter also features transient protection and other features that most cheap USB to RS-485 adapters do not have. This was important considering the long cable run out to the weather station. And, because the weather station hub runs at 3.3V and uses little power, the entire system can be powered from the USB port which provides 5V down the line.

I took this new USB adapter and hooked it up to a Raspberry Pi. Using a Python script I whipped up in a few minutes I was able to completely replace the functionality of the older Arduino-based system. While I haven’t added any new functionality yet, the Raspberry Pi allows for a lot more possibilities with its huge memory space, and the ability to SSH and VNC into it remotely. This solves the old problem of remote troubleshooting, which was basically impossible before. Local logs are also generated using the Python script to record errors and weather data in the event of an internet outage or other failure. I’m very happy with this improvement.

Grid Dip Meter

Grid Dip Meter
Heathkit HD-1250

A grid dip meter is, in it’s simplest form, an oscillator. One function of this device is to determine what frequency, or frequencies, a particular LC circuit is tuned to. This is accomplished by placing the device in close proximity with the LC circuit under test. Inductive coupling between the meter and the circuit being tested allows the resonant frequency to be measured. When the frequency of the meter is tuned to the frequency of the LC circuit under test a dip will be observed on the meters indicator. More information about how to use this device can be found on YouTube in a video by Alan, W2AEW.

HD-1250 Grid Dip Meter
Inside the HD-1250

I thought it would be interesting to take this little meter apart and see what’s inside. While most of us are familiar with how to use one of these meters, and what they look like on the outside, I’m guessing that unless you’ve assembled one of these nifty devices yourself that you won’t be quite as familiar with the parts inside.

In the photographs you will see some familiar components. The large device with the moving interweaving plates is the variable capacitor. This capacitor, along with the inductive probe chosen sets the frequency of the oscillator. Other big ticket items include the battery on the left, the variable potentiometer to set the gain of the front panel meter seen with the small thumb-wheel attached, and the single-sided circuit board on the bottom.

Grid Dip Meter Circuit Board
HD-1250 Circuit Board

I admire the simple sheet metal construction of these Heathkit devices. Their simplicity certainly contributed to their low cost, and high availability that made the Heathkit line so popular. I found the method they used to create a tapped mounting hole in the edge of the sheet metal to be particularly clever. This is a technique I could certainly use in the future.

The single-sided pcb in this meter looks like it was likely drawn by hand. This semi-artistic method of pcb design has gone by the wayside in favor of modern CAD software, but you can still learn a lot by studying these designs. I can appreciate the quality of the work here, especially considering it was done on paper.