By Roger Egan (VA3EGY)
This was our first Transmitter Finding (aka Fox Hunting) activity of 2021 and despite difficult times, we are pleased to see that a few of you were willing and able to participate. We hope to see these numbers grow over the coming months.
We wanted to experiment with a higher power transmitter this time to provide the community with a different and in some ways more challenging experience.
Roger VA3EGY, Harrie VE3HYS and Rob VE3RXH spent a Saturday earlier in the month, confirming the fox setup and propagation range. We drove around town taking S-meter readings at various locations. We learned a few things then and more during the actual event which we will share in this article.
We had 6 active participants and a few more who sent emails or posted to groups.io to confirm they could hear the fox but had decided not to participate this time.
Three people found the fox (Jeffrey VA3PEW, Michael VE3WMB, and Thane VA3TTM) and some shared their approach and challenges which we so appreciate and which they have agreed we can share in this article.
Where was the fox?
The fox was hiding at Scouts Headquarters, 1345 Baseline Road, Ottawa. There is already a radio shack there as part of the Scouts Museum. Harrie VE3HYS with help from Thane VA3TTM, and new HAMs Tom VA3TXL and Dave VE3FCQ, installed a new permanent tower with several antennas on it last fall for future activities including Jamboree on the Air (JOTA)
The setup:
A mid-1970’s Kenwood TR9000 VHF rig (http://www.rigpix.com/kenwood/tr9000.htm) transmitting at one watt over 90 feet of LMR400 feedline to a 42-foot tower and 4-foot mast with a Diamond V2000 (https://www.diamondantenna.net/v2000a.html) antenna (6.2dB gain) on 147.57 MHz mounted on top.
Fox Propagation Range:
From testing, we could hear the fox as follows:
- east to at least Hwy 174 and Montreal Road;
- south on Woodroffe Ave to past Barrhaven;
- west on Hwy 417 to Tanger outlet and;
- north from March Road, along Carling; Ottawa River Parkway to parliament hill
Houston…we had a problem:
Despite extensive testing, thanks to Harrie VE3HYS, Rob VE3RXH and Roger VA3EGY, we discovered the fox would intermittently stop transmitting and then restart on its own or with some assistance. It did this at least 3 times over the 3 days of the event. We still don’t know why.
The unit was on a power supply with automatic cutover to battery so the issue must be either an RF or static interference with the circuit or a software glitch in the controller.
We now have a 2nd controller so we can compare performance and hopefully work this out before our next event. Our apologies to those of you that reported you almost found it and then it disappeared. I guess it was behaving a lot like a real fox in that regard.
Participants Feedback
Jevin VA3JEV from the Ottawa Valley QRP Society. We are very happy to see more participation from the QRP group. Many thanks to Norm VE3LC for posting an advertisement on the Ottawa Valley QRP Society and the OVMRC groups.io pages. Everyone is welcome of course!
Jevin has a DF loop as per these plans he shared. https://qrm.guru/how-to-locate-the-noise-source-building-df-loop/ Thank you Jevin. I plan to build one of these myself to see how it works.
Jevin let us know that he could not get a decisive null with this antenna because there was just too much signal from his QTH. Next time, we suggested he might want to use a tape measure Yagi antenna from plans on the internet (http://theleggios.net/wb2hol/projects/rdf/tape_bm.htm) with most parts available at your local hardware store for around $40. There is a really good youtube video by KB9VBR on how to build this antenna at https://m.youtube.com/watch?v=BmHoQrDfw-0&noapp=1. And, an offset attenuator, like the kit we built as a club project last winter from KC9ON as a kit (https://kc9on.com/product/fox-hunt-offset-attenuator/) for about $20 or assembled (https://kc9on.com/product/fox-hunt-v6-smd/) for about $40. Maybe we will do a bulk purchase again if we see enough interest. Drop me an email at va3egy at gmail.com and let me know if you are interested in building a tape measure antenna, an offset attenuator or both.
Wray VA3EO reported: “I tuned my desktop 2M rig to the frequency and the fox came booming in. Wow what a signal! Anyway, I disconnected my indoor antenna and still picked it up through my coax. My HT even picked it up in my basement. So, my guess is that the fox is either in my garage at 21 Quinterra Court or possibly on VE3YY’s balcony on Uplands Drive. With all the reflections in the house, my coax loop sniffer does not do much good.”
I am sharing Wray’s feedback with thanks to Wray for being so specific about his experience in hopes that it will help others who were not able to get out this weekend, to prepare for the next one.
It’s one thing to have a fox transmitting on a few milliwatts that you have to drive around until you can hear it within maybe a 1-2 km grid, but with 1 watt, you really need to invest in some basic equipment (directional antenna and an offset attenuator) to be able to see a peak or a null in the signal for direction and a radio with an S-meter to know when you are getting closer or farther away from the fox. In Wray’s case he was fully 6km from the fox and the signal was just too strong without an ability to attenuate it.
Dave VE3FCQ, a new HAM in 2020, got his license to follow in his dad’s amateur radio footsteps. Dave bought one of our available offset attenuator kits and borrowed a Yagi. I don’t think he found the fox but he sure gave it a good try. I think he was out twice over the weekend.
There is no shame in not finding the fox, it takes practice to develop the skills and you definitely learn some new techniques and tricks every time. Feel free to reach out and tell me what you tried and I may be able to offer some of my own tips. I am not an expert but definitely willing to share as others have done to help me get started.
Jeffrey VA3PEW emailed us on Saturday afternoon. Jeffrey is a keener and has not missed a fox hunt in the past 3 years. Now Jeffrey is a software engineer and I think this background goes a long way to inspiring his problem-solving approach. On the one hand, he does not have an attenuator or a directional antenna. Instead, he uses his mobile rig with a hatch mount omni-directional antenna and uses his s-meter to develop a matrix of signal strengths that leads to a possible grid where the fox might be hiding. He said next time he wants to think about how the antenna placement on one corner of his vehicle is affecting the ground plane antenna gain pattern to further refine his plotting. Here is his email…
“Is the fox in the apartment buildings at the corner of Baseline and Merivale?
At first, I didn’t think I was going to figure out anything more specific than “Nepean” since the signal/range was much strong this time, but then I remembered I could add an +0.010MHz offset and then that signal dropped into a range that gave me more information, but I kinda had to discard the mental propagation map I had in my head at the time and start over…
But with that technique, I was able to narrow it down to that intersection. I didn’t notice any particular bias in any direction or shadows caused by buildings, so I figure it must be near the top (or on the roof?) of a tall building… I used Google Maps in 3D mode to see which buildings were the tallest in the area and did my lookup of ham addresses (via http://web1.foxhollow.ca/ccd/, doing searches like ” ottawa”) to see if there’s a correlation.
Perhaps the QTH of David Robert Parks VE3AV or Everett E Stevens VE3CYO?
Here is Jeffrey’s driving trace with numbers overlayed to indicate where he started (coming from Kanata) and each successive segment as he tried to narrow down his search area.
Jeffrey says he drove 47.6 km over 52 minutes and ultimately his guess was just a couple hundred meters from Scouts HQ. An awesome effort!
Michael VE3WMB, who also loves a radio finding challenge, lives in Central Park area which is right behind Scouts headquarters. Here is what he had to say on Sunday evening in just one short paragraph…
“Unfortunately, the beacon was down when I went out for my walk this afternoon, so I was unable to get an additional outdoor fix. This thing is really close, and it seems that I am getting some reflections making it seem at times like it is everywhere. However, I was able to get a rough direction from an upstairs bedroom, so I am going to make an educated guess that the beacon is located at the Scouts Canada Building on Baseline Road.”
Well Michael, you are absolutely right! Congratulations and thanks for sharing this picture of your rig display which shows a clean signal and a strong ERP with antenna gain.
And saving the best until last.
Thane VA3TTM, sounds like he had the most fun of all and gets an “A” for effort as well as the best ending for his fox hunt adventure. Here are some excerpts from what he shared with us…
“It took me a lot longer than I expected it would.”
I was not able to hear it from three of my attic mounted antennas, so at 2:00 pm Sunday, I drove to the top of Corkstown hill. I could hear it there with static with just my baofeng with the rubber duck.
I pulled into the ski trail parking lot to connect an 8 element Yagi, only to find out that it was using an RCA connector instead of an “F” connector. My 75-ohm to 50-ohm transformer has F on the 75-ohm side and SMA on the 50-ohm side.
I continued down Corkstown hill toward Moodie drive, where I lost the signal. I got the signal again briefly when I crossed the Queensway at Moodie.
I could not find an F to RCA, so switched to my 4 element Yagi and went back to Corkstown hill with the small Yagi connected to one radio, and the rubber duck connected to another.
I was not able to pick up the signal with the Yagi at Corkstown hill, so I drove to Moodie, and then went to Carling Avenue. (editorial note – this might have been one of the times the fox stopped and restarted intermittently).
On Carling, I could get the signal on the rubber duck, but I did not want to try to drive while holding up the yagi, and each time I pulled off Carling to park, I lost the signal.
When I got to Merivale Road, just using the rubber duck, the signal seemed to be clearer to the south than to the east.
So, I started to drive South on Merivale. When I got to Baseline Road, I started hearing the signal from the radio with the Yagi, even though the yagi was on the seat beside me pointed to the floor.
I decided I needed some place to park so I could get out of the car and wave the Yagi around.
So I went to scout HQ. There I could receive the signal on all sides of the building, and in all directions. I assume that the signal could be bouncing off all the tall buildings in that area. Where did you have the fox? Was it vertically polarized or Horizontal?
Editorial – Thane – thank you for this wonderful account. We all agreed that as far as we are concerned you found the fox.
One of Harrie’s Scout students borrowed a Yagi and spent some time searching. He actually started at the Experimental Farm which is very close but then headed to Carlingwood Shopping Centre parking lot. Harrie will have to spend some time with this fellow to help him get ready for an awesome experience next time.
I’m sure there were a few more of you that were out for a bit looking or using your beam and discussing locations on the OVMRC groups.io page, VE3VIG and VE3KMV come to mind.
In closing…
Congratulations to all who gave it a try and to Michael, Thane and Jeffrey for providing the rest of us with some things to think about between now and our next event.
If you would like to hide the fox in a future event, please get in touch with me at va3egy at gmail.com.
And a big thanks to Neil VE3PUE for creating and maintaining our website at https://ardfottawa.ca where you can find more information about equipment and upcoming events as they are planned. If you would like to be notified of upcoming events, please subscribe to our email list on this website.