Daily Archives: 6/3/2013

A trip to the Bale Grist Mill in Napa…

IMG_3385This weekend was kind of a loss for computer/geek/rc airplane/ham radio, but it was off the charts fun for me and the missus. We did an unplanned day trip up to the Napa valley on Saturday, and then when I realized that I had left my lucky hat at restaurant, returned on Sunday to retrieve it, and ended up having a great brunch at Brix (yum) and then took a tour of the Bale Grist Mill.

The Bale Grist Mill is a fully restored, water-powered grist mill that grinds grain. We saw the sign on Saturday, and googled it that night, and decided to return on Sunday and see what the tour was all about. It was great: the miller was there leading tours, and spent about an hour talking about the history of the mill, and then allowing us to view all the intricate mechanisms inside that serve to grind grist (the seeds of either wheat or corn) into flour or meal. For a small donation, you can even cart away some of the resulting flour for yourself. Since I’ve been baking bread a bit, I decided to come away with some bread flour, buckwheat, spelt, and some polenta. I’ll let you know how it turns out.

The most interesting thing to me about the mill was how refined the design is. Our guide said that many of the elements for the mill would have been taken from the design published in The Young Mill-wright and Miller’s Guide, first published in 1795 (and available for download at the link!). Its author was Oliver Evans, who received an early (the third, apparently) U.S. patent for an automatic flour mill. It uses the power of water to move grist and grain around through a series of bucket elevators and conveyors. The mechanisms visible at the Bale mill seem rather antiquated to us today, but if one considers the times, they would have been positively cutting edge. The miller, working by himself (perhaps with some “dusties”, or apprentices), could have processed as much as a ton of grain per day. And since lanterns and the like were not allowed because of the risk of explosion, that was just as long as daylight lasted.

It was a lot of fun. If you are in Napa, consider stopping by (and donating money, they don’t receive any state funds anymore). I had a blast.

A nice little explanation of the PA0RDT Mini Whip antenna…

Like many people, I live in a development with a fairly restrictive HOA. This means that I have to be fairly careful to use largely invisible or stealth antenna setups. Because of a lack of suitable trees on my property, this means that I’ve had fairly compromised setups: I’ve gotten the most use from a simple 40m dipole which probably only averages about six meters in height.

But at least for receive there might be an interesting alternative. PA0RDT has developed a simple active antenna which has intrigued me.

Here is DL1DBC’s excellent description.

This article points out something which may not be entirely obvious until one thinks about it: antennas designed for transmission and reception have different goals. A transmitting antenna is designed for efficiency: to send as much of the input power out as radio energy as possible. In this context, short antennas have a very low radiation resistance, so other losses tend to dominate, and you lose a lot of power as heat. But receive antennas aren’t concerned with efficiency: you really just want to preserve the signal to noise ratio of the incoming signal. As long as the noise generated by the preamplifier is low, it doesn’t actually matter how efficient the antenna is. A short antenna picks up less of the desired signal, but also picks up less of the surrounding noise. So, these antennas can work reasonably well, especially on frequencies where full sized antennas are impractical such as VLF.

PA0RDT has created a simple preamp circuit, including a way to power the preamp through coax so you can easily mount this antenna remotely, say 50 feet from your house, and avoid the electrical noise that dominates many active antenna setups. A very neat solution, and inexpensive.

Some more links: Scott built one, using the more ubiquitous MPF102 and 2N3904 transistors, instead of the recommended but harder to find J310 and 2N5109 transistors.

Peter Marx got an official one that was built by it’s creator, Roelef Bakker:

You can read about Peter’s experience here.

A neat little project. Roelef’s articles (esp. the second one) linked from DL1DBC’s give lots of details. Worth looking at, particularly if you are interested in VLF/HF/shortwave listening.