Blog Archives
I haven’t updated this in a while, not that there hasn’t been anything to update, it’s that I’ve been pretty busy.
In the past several months, I decided my trap vertical antenna in the backyard is a piece of shit. While operating in the 13 Colonies special event, I felt like I would have fared better yelling to people than using the radio. And playing some JT-65 after that made me think that the vertical is either sending everything straight up with no possible shot of reflection, or straight down in the ground. Not to mention, the guy behind me hates the thing. I think it pisses him off that he (not in my “community” can’t get the HOA to do anything about it. I haven’t been exactly secret about it’s existence, it is just that I don’t have a tower and a vertical hidden behind some trees isn’t in full view of my neighbors or the street. Well, except that guy, and he doesn’t count because he doesn’t pay into our neighborhood HOA. The HOA president has made it clear to me that the HOA will not get involved unless someone in the HOA has complained and nobody has.
My master plan was to finish a trap dipole antenna the weekend before the ARRL Sweepstakes and try to get on and at least make it half-way to a sweep. By finish, I mean that I’m going to build traps for 10, 15, 20, and 40 meters, tune the antenna, put it in the attic, and run cable down the ventilation shaft in the middle of the house.
So I learned a few things. One is that there is no way in Hell to do this without a good antenna analyzer. Another is that you should use the site that says “I constructed my traps using good quality RG-58/U coax scavenged from a discarded 10BASE-2 Ethernet cable.” should be used as guidelines. I don’t care how good quality of 10BASE-2 cable, no network administrator has used that shit since 1990!
Anyway, I found 100 feet of RG-58 to try this with (and at a damn good price). I realized almost immediately that this wasn’t going to work because damn good price is code for shit quality – the braid is aluminum. When I saw that, I immediately thought “WTF???” and tried to solder it just to make sure it wasn’t silver-colored copper or something else. Nope. Aluminum.
So I tried to make traps out of it using crimp connectors, which could have worked, but the crimp connectors don’t work too well on braid.
The following weekend was spent partially in Columbus for a meeting (on Saturday). Not being one to wake up at 4:30 AM for a long meeting, I went up on Friday and had even arranged another meeting at 2:30 in the afternoon. After that meeting, I dropped by Universal Radio and thought about buying some RG-58. Since they didn’t know if it was copper or aluminum braid, I bought RG-8X. With copper braid 🙂
Then came a weekend of winding traps. Ironically, this was on the weekend of the ARRL Sweepstakes. After having much difficulty, I found this awesome little piece of software by Tony Field, VE6YP. It is a coax trap calculator. Coax traps are a pain to make because the higher (than normal, or relative to most things a ham would build) Q. So after finding references to the capacitance per foot of “normal” RG-8X and inputting the other parameters, I found some combinations of PVC plumbing fittings and numbers of turns that would work. Of course the final traps I built, for 40 meters, were off, so I had to make a fix to those (and thank God I didn’t have to re-wind them, as I had run out of the coax I bought at Universal).
The following long weekend (Thanksgiving in the US) was spent with fixing turkey, pumpkin pie, and those 40 meter traps. I also tuned the antenna and hung it in the attic. That’s where I’m at. I tried to run the feed-line (that shitty RG-58 with the Aluminum braid, thanks to some crimp PL-259s). It’s stuck in the wall. I’m not sure how it is stuck, but I’m guessing there is a wire nest right between two sheets of OSB separated by the 2×8 flooring. Don’t ask me why there are two sheets of OSB. Normally there would be one on the top and nothing on the bottom (there’s drywall on the bottom of those same 2x8s where it’s above the living spaces, but there’s no need to have it below the floor in that area, especially with it being only a 2′ x 3′ space.
So I’m sitting here thinking “how do I get this damn wire down?” I really don’t want to pull it back and re-run it, but I may have to. I’ve been wondering if I can grab it with something, but it is 8 feet up the wall (guessing).
On the vertical, I think I’m going to leave it up for a while. It’s fuglier than sin, but since my neighbor supposedly (key word!) called the township who called the FCC a year ago but the only person to talk to me was our HOA president (the township zoning admin talked to the president and the HOA president told me all this), I’m not foolin’ with it. If they want me to do something, try talking to me. I’m not really a bad guy.
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I registered KE8P as a vanity and it was approved today. This site, AC8JO.us will still work for a while though, as I just don’t feel like (or have the time) changing things over.
I am considering building a frequency counter. In part of that, I’ve been learning and playing around with logic chips. I started by playing with a few decade counters and setting those to count based on pulses from an Arduino. As I continued, I felt the Arduino was too slow and replaced it with a 555 timer used as an astable multivibrator and only used the Arduino as a power supply. Then, just to mess around, I put a photoresistor on it and used it to adjust the frequency. Below are the Fritzing image and a video showing how it works.
Since I’m not an electrical engineer and they teach nothing about oscilloscopes in traffic engineering classes, I’ve been viewing lots of videos about using scopes on YouTube. After seeing W2AEW’s video, I thought I’d get an Arduino and make a “poor man’s TDR” (as he calls it) by having the Arduino output pulses.
This is really quite simple. Too simple.
So simple it didn’t work.
Initially, it looked pretty good. I don’t know about the accuracy of the Arduino, but I imagine that it is good enough. The problem, I’m guessing, is the current. An Arduino is pretty limited (40 mA), so pushing it through a cable and expecting it to be able to act like the video might be pushing it.
Anyway, for the sake of showing, here’s what I did…
The Arduino Sketch
The Circuit
It’s pretty simple. Plug the scope probe into pin #7 and ground the scope probe ground to the Arduino.
The Results
Without any coax or with a ~6 foot piece of RG-58 open at the other end, I can see the step from the pulse. But when I connect a 50-ohm dummy load, the voltage drops.
Without a load:
With a load:
Note the difference in voltage between the two. I had the scope set to DC for these to keep the baseline the same, and the voltage per division was 1V.
Back to the drawing board.
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This post is about the recently-built and the to-be-built projects I’ve been working on.
Recently Built: RF Sampler
First off, the recently-built. I recently built an RF Sampler. This little device allows me to connect a rig under test to my oscilloscope. The schematic is quite simple, as it is basically a voltage divider that divides the voltage between an internal resistor and a dummy load. Below are the pictures.
And what are pictures without a video to show it works?
The schematic for this is at http://www.qsl.net/k6ls/rfsampler.html. Also note this video from W2AEW (which is an expanded design of this).
Recently Built: Octopus Tester
Another item I recently built is an octopus component tester. This is a simple tester that makes some basic tests on electrical components, like capacitors. You can’t get the value of capacitance (etc) from this, but you can see if it works by hooking it up to the tester and checking it on an oscilloscope. I built this into an Altoids tin.
Below is what a capacitor looks like on the scope.
More information on this can be seen on W2AEW’s video.
In The Pipeline
I have one item in the pipeline, maybe two.
One of them is a Time Domain Reflectometer. There are schematics for that in the ARRL Handbook. This would help me test coax. I may jump to an Arduino-based pulse generator first.
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Friday was my first full 3 mile run. I had thought that Wednesday was the first, but after looking back at the track on the computer, I found that it was 2.75 miles. I’m not too happy about that.
My runs are 5 minutes walk warmup, 3.0 miles run, and 5 minutes walk cool-down. After the walk warmup on Friday’s run and a few hundred feet into the running portion, I pressed the status button on my earphones to hear the distance remaining. 2.74 miles. W. T. F?
I quickly stopped my workout on Endomondo and deleted the 5 minute warmup and restarted the workout. This time, after a few hundred feet, Endo said 2.99 miles remaining. Much better!
Towards the end of my run, I did have to make a route adjustment because of the Reds’ fireworks show for that evening closing part of the sidewalk for setup, but since the Reds beat the Pirates and continued their climb in first place, I’m okay with that.
It is now 6 days to my first 5K of the year, The Brian Rohne Memorial Run.
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I saw a commercial on the news recently that struck a cord. It was for a phone app that “keeps your family safe in a storm”. I then saw an ad for the same app on that local news station’s Web site.
I’m a trained weather spotter, a member of the local Weather Amateur Radio Network, and a member of the local ARES/RACES chapter. I know NEVER to rely on a cell phone during a disaster. We had earthquakes in Cincinnati that caused NO DAMAGE and the cell phone network got slammed (because of everyone tweeting/etc about the quake). If that’s the case, what do you think the cell network would do in a tornado? We saw it on March 2nd – it went down.
The only safe thing to do is to have a weather radio!
I have a Reecom radio I bought from Amazon. It works well, and I was able to configure it to only do alerts for Clermont County (my county) and only for major warnings – it would blink (but not sound an audible alarm) for flood warnings (which do not affect my home) and severe storm warnings (important, yes, but I usually already know about those).
If you want to go one better…
If you want to go one better, you can get a scanner and listen in on the ham radio ops (we’re on 146.88 Mhz and 147.375 Mhz in Cincinnati during severe events). Of course, you’re only getting part of the story because police use their own radios to report (you can get scanners for that, too), and weather spotters can also use their telephone to report weather events.
Should you not download the app?
I’m not saying not to download it or use it. If you’re in the office or at home and your cell phone is using wi-fi (and you have power and Internet), you’re probably fine. I’m saying that once those lights go out, you should already have a weather radio. Don’t let one of these phone apps give you a false sense of security.
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Everyone on Twitter that follows me (@ac8jo) knows I’ve been running. This is not a new thing to me, but unlike people like N8TFD and KB2HSH who can run marathons, I can’t.
Anyway, for the second time, I’ve embarked on the Couch to 5K plan with the intent to prepare for the Brian Rohne Memorial Run, which is a fundraiser for a scholarship and the NKU Cross Country team (and Brian Rohne is my late older brother).
This time things are a little different. For starters, I’ve looked harder at the C25K plan and realized that the times in the routines are not for me. I run too slow for those times, so I started using the distance intervals in Endomondo Pro. This makes things a lot harder, but also a lot better at preparing me for a 5K. I’ve noticed that I’m running a lot farther during my runs. I’m not a fast runner, but that will come in time. For now, I’d really like to be able to nail that 5K.
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Over the past week, I did a service event with CARES (Clermont Amateur Radio Emergency Service) roving around at the county fair. This was done in conjunction with the county sheriff’s department, who likes to have some extra sets of eyes around.
An event like this involves a lot of walking around, and doesn’t always lend itself to a normal “go pack” that would fit in a backpack, since the added weight would feel really heavy (no matter how light). In addition, since we’re talking about a fair, there is a lot of people and amenities around, so we don’t have to be in “survival” mode. However, during the week (on just about every day), we’ve been hit by strong thunderstorms, and my night at the fair was no exception.
Prep: Attire
During the days here, the temperature has been hitting the 90s, so shorts and short sleeves was the order of the day. We have vests to wear as well. Fortunately, our vests have pockets on the inside and outside (a definite plus!). The vests also have a pocket in the back that was excellent for a rain coat. Of course, I had shoes on, but the not-very-smart thing I did was use my nicer running shoes (instead of the older running shoes I use when I mow the lawn). Either way, comfortable athletic shoes were the best to go with.
Prep: Stuff
The things that worked was my Wouxun dual bander, speaker/mic. I had a battery pack with AAs in my back pocket.
The thing that could have worked better was my earphones that I was using with the speaker mic – I had a stereo set and one side did not work. Also, the cord was way too long.
What did not work at all was the water bottle I brought. I had one that was refillable, and being out and away from the truck meant that I had to carry it with me. I should have brought a disposable bottle with me that I could dispose of when it was empty (there was no good place to refill the bottles).
I also had a small notepad, two maps of the grounds, a pen, and my EMA ID card (along with my normal driver’s license and amateur radio license). Most (if not all of that) should go without saying.
Prep: uh… prep!
This goes without saying, but MAKE SURE YOUR RADIOS ARE CHARGED! Nothing makes you look worse than having your battery die in the first hour. I recommend having two radios, both charged, and also having a spare (charged or AA) battery pack.
Make sure your frequencies are in memory, and set the radios to that memory prior to turning off the radio when charging (most will remember the frequency). This goes double for radios like Wouxuns that are notoriously known for being difficult to program in the field.
Landing
When you get to the location the first and obvious thing is to check in (following the protocol of your group).
Remain observant. I was there when I almost needed to call for a medical unit (fortunately it came out to be nothing).
Be where the people are. My partners in fighting crime (the other CARES ops) saw a fight and because they were where the most people were (at the grandstand watching the demolition derby). That doesn’t mean to ignore the rest of the complex, just make sure those places are covered (another great reason to wear bright-colored vests, as it makes it easy to see where others are).
Next up: HFP race event.
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