KK6WLD Radio Related Reports
Entry for April 12, 2017
Well propogation tonight wasn't great. Only heard W6RIP, but that was enough to still have some fun and to run some more field tests on the Beam. Assembled it in about the same spot as last week during the PAPA System New Ham Net, and checked in to PAPA 4 with KK6LMC who was running net control. My one watt was till making it clearly, so that was a good sign the antenna suffered no ill effects depspite having a bent element (I un bent it as I assembled it).
So off to the simplex net, and I aimed a little bit or right of where W6RIP's signal seemed strongest (and using my compass that seems to have ended up a hair west of North, although I'm a little suspect of that and will have to check my compass at some point). Heard a bit of scratch during a couple station's check-ins (including KI6LOV), but nothing copyable. Kevin was nice and clear, although a tad weak (sorry Kev, you got wiped out a couple times with whatever local noise bursts that seem to pop up occasionally). No relays from San Diego (doubt there's many people trying from San Diego, but you really should).
Now for the interesting field tests. I did get the antenna switch (a Diamond CX210A) so I could switch to the more omnidirectional magmount on the roof of the car. After the net, I talked to Kevin, and he told me that he couldn't hear me when I switched to the mag mount calling for relays, but I was coming in clearly with the Beam. So that called for some more testing. First off, make sure the switch isn't bad. So I tried switching the ports and keying up PAPA 4 with the mag antenna with 1 watt. No response. Switching to FULL POWER (all of 5 watts! :) ), I got a return beep from PAPA4. I remembered the net feed, so I tried again, with the nice long delayed net feed and could barely make out my own call sign. Well looks like the beam's working wonders. But as I was putting things away, I realized there's a lot of loss along the way from my radio through the car to the mag antenna. The set up goes like this:
Radio with male SMA, male/femail right angle so female SMA to female UHF pigtail. This is constant for everything. Then I had the antenna switch with UHF connectors all around. Then there's about 15 feet of RG-58 that runs through the car with male UHF connectors on each end. I've got the cable coming out the drain plug in the spare tire well (don't like drilling holes), so there's a double female UHF coupler followed by a male/female UHF right angle to head towards the back. Then the 17 feet of whatever cable comes with the MFJ-336M mag base wrapped around the bumper a few times to take up the slack.
Ok so now you know there's a lot of loss through the car. To finish the story, I went and unhooked the antenna coax from the 90 degree UHF connector under the car, and hooked it directly to the SMA-UHF pigtail on my radio. And low and behold PAPA4 responds on 1 watt for me! Have to say though, it was only slightly less scratchy on the not very instant replay than the 5 watts was going through all that mess.
So my lessons for the evening: lots of room for improvement in my car set up (will have to research switching to N connectors, and maybe get a crimper so I can chop some antenna coax length off). Also, the beam does seem to help a bit, though obviously at the cost of having to aim carefully (yes I tested when I aimed more than 45 degrees off from Kevin, he went away).
Well that's it for now. Thanks again Kevin for all the fun. Till next time. One of these days, I really would like to get a map of my actual radiation pattern on that beam. Clearly it's got at least a few dB on the SuperGainer (which I still maintain is a great antenna especially compared to TRAM 1185 that was my first magmount, but that's a story for another day).
Entry for April 10, 2017
Well it's really a follow on to the April 5th one. I figured (and Matt (KM6BSB) wanted to see them) I'd add on some of the plots from the simulation that I hadn't put up last Wednesday night as it was getting late in the evening. So for your viewing pleasure:
To get an idea of what the radiation pattern supposedly looks like, and where it's aimed. Sometime maybe I'll try to actually test out what it is in practice, but that's another weekend's project.
The modeled SWR plot is different from what I measured with the meter. Not sure what's causing the difference, and messing with the model hasn't yielded a closer fitting graph. Models are meant as a general guide anyways so PPPfffft!
NOAA's predicting some winds for Wednesday night, and some moisture. So we'll have to see if I bring out the beam again this week. Hopefully conditions will cooperate.
Entry for April 5, 2017
That said, I'm starting this page for a couple reasons. One: Matt (KM6BSB) keeps bugging me to, and two: because of tonight's Greater Los Angeles Simplex Net. Propogation was awsome, but more importantly (well probably not, but it couldn't have hurt!) was the first field trial of my home built Cubical Quad Antenna. So without much further adu, here's a couple pictures!
There's the antenna in all it's glory from the location just off the glider port that I checked into the Simplex net tonight. You can see my normal Diamond mobile antenna on the roof. I've got the Quad hooked to a Baofeng UV-82HP clipped to the arm rest on the door. The radio's spec'ed for 7 watts on UHF, but only puts out about 5 watts on a fresh battery (had one this time), and run through a female SMA right angle, followed by a SMA to SO-239 converter cable.
So there's a close up of the elements, looking back up the array from the business end. The boom was aimed for best signal from W6RIP netcontrol for tonight's Net. And in posting this picture, I realize I had the reflector on backwards. Still seemed to work pretty well though.
I based the antenna on dimensions for 446MHz, although due to construction and measurement variation, a couple of the wire lengths ended up about an inch short. The simulation using MMANA-GAL Basic seemed to show the resonance up around 448-454 MHZ, depending on which of my measurements I used. But the my Diamond SX600 seemed to give me a my low SWR point of 1.1:1 around 440 MHZ. A couple forum posts around the net seem to indicate that running wire through PVC pipe can elongate the effective length of a wire, and I'm still working through the details of that, but could explain a little bit of difference. And my wires aren't very straight, so they probably are a little longer than my measurements might indicate. In anycase that's ok, it seemed in the right ballpark, and even had a 1.3:1 SWR up at 446 MHz. But, MMANA-GAL has an optimizer function, and given the purpose of this build was an awsome antenna for the simplex net, I ran the optimization with a focus on gain. The results generated some vastly different spacings for the elements, so I took those with a grain of salt, and some gut instinct (or just random assignment) and shifted the spacing between elements. Hooked it back up to the SWR meter, the SWR seemed to be very close to 1:1 right at 446.5!. Ran a few tests in the kitchen, then packed it up the next day (today) and re-set it up out at the glider port. Checked the SWR and it was actually still about the same. Woohoo!
All in all, it was a pretty good net. I heard 15 stations, including netcontrol W6RIP, and even could just make out W6TYL up in Tarzana. I'd like to thank KI6LOV and K6JSD for their signal reports and follow up comments. And of course K1KMO and W6RIP for organizing and running the net. I should also thank the PAPA System for running the VE sessions that allowed me to get my License, and for running the New HAM net that's encouraged me to stay Radio Active (and also where I found out about the simplex net). I should also thank my housemates (who's callsigns I may include later if they choose to be included) for putting up with the mess in the kitchen as I went through multiple itirations of each of the three versions of this antenna. It's been a lot of fun. Hopefully I'll be able to make it in more often even when propogation isn't quite as good. It's been an interesting few weeks' worth of evenings and weekends filled with measuring, cutting, bending, and soldering. Learned a few things (like get a nice big fat solder tip for soldering larger wire, and my 50 watt soldering iron goes from 10-38 watts in the last couple marks) along the way. I don't know when I'll update this page again, but with some encouragement, hopefully it won't be too long in the future.
Oh, and it looks like I succumbed to the modern age. I used a bit of CSS styling for tabs since I'm super lazy and didn't feel like hammering out white space code. Next thing I know, this site will have HTML5 Video!
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