Josef “Jeff” Sipek

The jeffpc Amateur Radio Fox

There is already a number of different fox hunting designs out there—both commercial and hobbyist built. Therefore there is no practical reason to make another design, but educational and entertainment reasons are valid as well.

So I made one.

I put together a project page which talks about the project a little bit but mostly serves to point at the source, binary files, schematic, and a manual. Since it doesn’t make sense for me to repeat myself, just go over to the project page and read more about it there ;)

Finally, this is what the finished circuit looks like:

As always, comments, suggestions, and other feedback is welcome.

September 2022 BCRA Fox Hunt

This post is about a Wikipedia article: fox hunt organized by the Bristol County Repeater Association in September 2022. (Information about the last/next fox hunting event.)

Unfortunately, I didn’t get to participate in the BCRA June fox hunt because it conflicted with the ARRL June VHF contest. As a result, I was rather excited to participate. Just like last time, Holly joined me.

Our goals were:

  1. Find the two foxes.
  2. Find the foxes quickly enough so we could head back home and enjoy a little bit of Arlington Town Day.
  3. Wipe the floor with our competitors—namely KM1NDY and AA1F.

We were going to keep the last goal to ourselves, but during the fox hunt check-in at 9:45am, Mindy threw some shade in our direction…so, I guess that’s the kind of game we’re playing. ;) (For the record, Marc and Mindy were accompanied by Jeremy. So, they had three hams on their team.)

This time, the two foxes were within a 5-mile radius of Church St in Wikipedia article: Swansea. I like this. A 5-mile radius is still a lot of ground to cover but avoids having to drive for a long time.

For the most part, this hunt was like the last one. I used the same Alinco handheld with the same home-built yagi. I jotted down the measured vectors on a map on my iPad. The major change since last time is the addition of a second radio—a GT-5R Baofeng handheld with a small loop antenna I threw together a few nights ago. I’m not sure how much it helped, since the Baofeng is both poorly shielded (and therefore picks up strong signals) and kind of deaf (and therefore doesn’t pick up weaker signals).

Inspecting the map while enjoying breakfast in a Dunks parking lot a couple of miles north of Fall River, we concluded that we should start the hunt near I-195 in Fall River. That way, we could quickly get to the other side of the river if it turned out that both foxes were on the other side.

(The higher resolution map resulted in my annotations being kind of small when zoomed all the way out. The ~2MB full-sized image shows them better.)

The first vectors were rather disappointing. The first fox (which we dubbed the red fox), seemed not too far away but not very close. The second fox (blue), was very weak and apparently on the other side of the river. Well, that’s what we got from the Alinco+yagi. The Baofeng+loop got nothing.

Driving to stop number two, Holly picked up a little bit of the red fox’s second transmission. This was encouraging—the loop wasn’t completely useless and hopefully we were getting closer to the fox. Unfortunately, the first and second red fox vectors disagreed a little too much. So, we drove a bit further to see which direction it would confirm.

At stop number three, we concluded that either the red fox was down near the water or somewhere on the other side of the river (but not too far past it). Recalling the back-and-forth driving we did during last year’s hunt, we decided that our next stop would be near the bridge, which should tell us which bank the fox is on.

The signal got a whole lot stronger at the fourth stop. So much so that we thought that the fox must be in or near the nearby cemetery or park. This is why you can see stops 5–8 so close together on the map. After getting a very strong signal (even with 16dB of attenuation) at stop number 8 (and not having too many convenient places to pull over) I started to circle the various blocks looking for parking lots where someone could park for the 4+ hours of the hunt to act as a fox. While I was circling, Holly was trying to use the loop antenna and looking at the map.

Soon enough, we happened onto a parking lot for a strip mall. We drove around the lot, not seeing the Jeep we were expecting. So, I pulled into a spot to regroup and get another yagi vector when I noticed that a car on the other side of parking lot had two antennas on the roof. Sure enough, it was Skip’s Jeep.

We were the third ones to find it. (I didn’t actually note down the time, but it was something like 11:15-11:25, so somewhere between an hour and hour and a half since the start.)

You can see that I stopped jotting down blue fox’s vectors after the 4th stop. That is because we concluded that it was on the other side of the river and because it was weak, it was probably far enough that we’d just continue getting essentially parallel vectors.

Next stop (#10) was Home Depot. Well, their parking lot. It is large and it is easy to get out of the car and swing the yagi around. The signal was stronger, but that’s all the new information we got. So, looking at the map, we picked a spot about halfway between the Home Depot and the edge of the 5-mile circle.

There was not a whole lot in the vicinity of stop #11, so we just pulled over on a side street. Unfortunately, due to a timing error on our behalf, we missed one transmission. So we had to wait for the next one delaying us 5 minutes. The vector we got was confusing. It pointed north, but was weaker than the Home Depot one. On a gut feeling, we chose to ignore it and continue west. Just as we were going to get into our car, we were approached by a woman who lived in the house near which we stopped. After I explained that we were doing a ham radio fox hunt, she wished us luck and headed back inside the house.

Our penultimate stop was the parking lot of a middle school in Warren. There, we got confused because we heard the blue fox transmit 2.5 minutes early, and then right on time. After briefly considering that someone was transmitting a fake fox signal, we decided to trust the vector and follow the RI-136 north, hoping to stop around the middle for another vector.

While driving up RI-136, I started looking for a good place to stop…when suddenly I noticed a blue pickup with a “BCRA” sign in the window. A quick turn into the adjacent parking lot and a little bit of parking lot hopping later, we pulled up to Kevin’s truck at 12:01. We found out that we were the second ones to find his fox, and that earlier, due to a technical issue, he transmitted off-cycle.

After chatting for a few minutes, we headed home, walked downtown, and got tasty burgers and beer.

So, to recap: we found both foxes, we found them in 2 hours and 1 minute, got to enjoy the Arlington Town Day, and last (but definitely not least) I think we wiped the floor with the KM1NDY team. ;)

Edit: Mindy wrote her own blog post about the fox hunt.

BCRA Fox Hunts (2021)

This post is about two of the Wikipedia article: fox hunts organized by the Bristol County Repeater Association in 2021. (Information about the last/next fox hunting event.)

July 31st, 2021

This was my first fox hunt of any kind. To improve the chances of success I teamed up with KM1NDY and AA1F. They participated in at least one BCRA fox hunt before, so they knew what to expect. (You can read KM1NDY’s thoughts about the hunt on her blog.)

The “parameters” of the hunt were simple: find the transmitter transmitting every 5 minutes from somewhere within 5 miles of exit 13 on MA 24.

Everyone likes to talk about gear, but at least in my opinion it is much more important to have a good strategy than to invest in specialized gear. That idea, combined with not knowing whether I’d like fox hunting or not, meant that I was going to use what I already owned. That meant WA5VJB’s cheap yagi and an Alinco DJ-G7 handheld. As far as non-radio gear is concerned, I brought my iPad to use for an annotated map.

I already talked about the antenna in my ARRL June VHF contest writeup, so I won’t repeat myself here. I got the Alinco handheld because I wanted a handheld with a third band. That narrowed my options down a lot. Since I heard good things about the Alinco and having a 1.2 GHz capability seemed cool, I went with it, even though the Boston area doesn’t have any sort of 1.2 GHz activity.

We decided to meet up at Wikipedia article: Massasoit State Park. That made it easy for me to do a POTA/WWFF activation after the hunt.

My co-conspirators were running a bit late, so I got to make the first “measurement” from the park parking lot alone. You can see it on the map labeled as #1:

As you can see, I went relatively low-tech on the map annotation. I just took a screenshot of a reasonably zoomed map and hand-drew the 5 mile circle. Then, during the hunt itself, I just eyeballed the direction of each measurement and noted it down.

When KM1NDY and AA1F arrived at the park, I shared with them my measurement. After a brief discussion about where to go next, I hopped into their car and we headed west to get back to the highway.

I won’t bore you with turn by turn retelling of the whole trip. I will, however, mention a few observations. In no particular order:

  1. Even the eyeballed arrows on the map are more than sufficient to get an idea where the transmitter is.
  2. The built-in attenuation in the Alinco handheld is super convenient, and pretty much all that I needed.
  3. Knowing the fox can help a ton—E.g., Skip (KB1CNB), acting as the fox, is known to like coffee shop parking lots, so looking there first is wise.

October 23rd, 2021

Between this and the previous BCRA fox hunt, I got a chance to do some on-foot fox hunting thanks to K1MJC who hid a fox several times in nearby Wikipedia article: Waltham. This time, I decided to try the hunt by myself (well, with Holly) and left KM1NDY and AA1F to fend for themselves—or “once our partner and now our competitor” as KM1NDY put it in her writeup.

This was a bigger hunt. The radius was 10 miles centered on the Veterans Memorial Bridge in Fall River and there were two transmitters!

Given the size, I decided to make a better blank map. I stitched together a couple of screenshots and then drew 5 mile and 10 mile circles. This turned out to be mostly useless since both foxes were within the 5 mile circle and we hadn’t even picked them up before entering the inner circle. Just look at the annotated map:

I didn’t even bother to try to capture all the information on this map because of how close everything was. When I got home, I ended up redrawing the map to show all the detail based on the above map, notes I made on the side, and what I remembered.

As you can see, we started off getting measurements for both foxes, but soon afterwards thought that we were relatively close to the blue fox. After driving between the two banks of the river far too many times, we gave up on the blue fox and tried our luck with the red fox.

Hunting the red fox was pretty straightforward, and before long we found Skip (KB1CNB) in his car playing the role of the fox. Skip told us that the other fox (blue on our map) was on the other side of the river. This sort of helped. So, we headed across the river.

Looking at the map now, it is clear which measurements were real and which were erroneous, but it is much harder to sort it all out when you are driving around not knowing where the fox is. :) We got really close at stop #20 where we got two equally promising directions. Sadly, we followed what turned out to be the reflection instead of the real one because we assumed that the blue fox was, much like Skip’s, a car in a parking lot. It wasn’t. The fox was on a step ladder in someone’s yard. We were clued in to this when someone mentioned it on the BCRA repeater.

I should know better, but I’ll promise anyway to write about my fox hunting strategy at some point in the future.

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