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And here is some information about using a GPS to set the clock on a Raspberry Pi…
One of the items that Jamey mentioned during his presentation is the desire to increase the display resolution of the RPi to better accommodate WSJT-X. Here’s a thread that I found that talk about how this can be done. I have not had a chance to try the idea in the thread but I thought that this information might be helpful.
Hi Bill,
You are on the right track with the idea that you can “measure” the effectiveness of your vertical antenna by using an antenna analyzer to measure its impedance. For this approach to be accurate, you’ll want to make the measurement as close to the feedpoint of the antenna as you practically can. As the length of the coax cable between the antenna and your analyzer grows to more than a few feet, it will begin to distort the measurements somewhat.
An “ideal” 1/4 wavelength vertical with a good ground system will have an impedance of about 25 ohms. As the efficiency of the ground field decreases, the impedance will increase towards 50 ohms. You will see a capacitive impedance if the vertical radio is “short” compared to a 1/4 wavelength on the frequency that you are measuring and an inductive impedance if the vertical radiator is “long”.
Radials are difficult on a boat as the associated wires will tend to end up in the boat’s propeller or drive. I don’t have any experience with putting antennas on a boat but the idea that you mentioned in a previous post of using copper sheeting on the inside of the hull to couple the ground side of the antenna to the antenna seems “right” to me. The idea is to create a capacitor using the boat’s hull as the insulator and the “saltwater” on the outside of the full as the opposite plate and ground. I would expect this approach to work quite well. It might be possible to do this with strips of copper sheeting laid as radials inside the hull as well.
I hope that this helps you,
Hi Bill,
Welcome! We’re glad to have you join us as an Internet Subscriber. We hope that you enjoyed Bootcamp.
The best thing that you can do to improve the performance of your vertical antennas is to improve the associated ground plan.
Scott, NE1RD just wrote a good article about radials and that may give you some good ideas about how to improve the first of your antennas. Here’s a link to Scott’s article.
It sounds like the setup in your boat will be more challenging. Water (especially salt water) can be an excellent ground plan if you can figure out how to couple the ground side of your antenna to it.
I hope that this helps you and again, welcome! Please continue to post here and we’ll try to help you.
Best and 73,
[caption id="attachment_77410" align="alignnone" width="1476"]
Raspberry Pi Case with Fan[/caption]Hi Hamilton,
There are lots of good case choices. Here’s one that we’ve used with some good results.
This is the 4B version of the case that we used for our video players at HamXposition.
Have fun!
You can also view the Pileup Operating Video that is part of this Tech Night on our Video Collection page. Its the last video in the archive labeled Instructional and Demonstration Videos.
Hi Greg,
It’s great to hear that you’ll be able to help with Boxboro. Dave K1DLM is doing the schedule and I’ve forwarded your note to him. You should hear from him sometime during the next few days.
Looking forward to seeing you at HamXposition!
Fred
Just a note on this presentation. If you look at the PDF of the slides in the archives at the bottom of our Tech Night page, you’ll find a couple of tables with links to Rohn’s specs and much of the gear we used on our towers. Also, you can find Matt, KC1xx who did the work on our towers at –