Forum Posts

Donald Giles
Dec 10, 2020
In Show off !
So far, AL7CR and I have launched 3 flights using the ZachTek PICO transmitter. Our first two were successful (for beginners) with the first one ending up somewhere near Hudson's Bay Canada and the second one went all the way to the IRAN/AFGHANISTAN border before we lost contact. We had anticipated that these two flights would be lucky to make it to the state line! Our third flight contained some major changes which we are still considering. We used two Chinese clear party balloons attached tail to head using our heat sealing roller machine. Until this time we had only used a single balloon per flight. Also, I split the free lift between the two balloons which was probably the wrong thing to do. We lowered the solar panels about another 10 degrees thinking that Fall would not provide the same amount of sunlight and that a lower angle would capture more solar power. We thought we needed some more altitude in order to avoid WX problems and that 2 balloons would provide that. The launch of the the flight was quite nerve racking in that, although it was perfectly still, the balloons did not want to rise and had a difficult time clearing the trees on a ridge to the north of the launch site. Our other flights were up and away gaining altitude quickly. Secondly, the balloon went north from our place and drifted for about 40 miles until it turned and came south again and finally went east. It crossed Texas and we lost contact with it near the Louisiana border. Again we think weather was a factor since we were only at 26,000' or so. So, we are now planning our 4th flight. Dean, AL7CR, assembles the hardware at his shop in Oregon and ships the transmitter and antenna to me here in NM. We think NM is a favorable launch site since we are at 7,000' elevation here. I figure out the free lift tests and basic testing of the transmitter. They have always worked very well. Then we decide on a launch day and if the weather cooperates we let it go. We have always only used 20 meters for WSPR transmissions. We are making some changes to the antenna system that will hopefully cut our payload weight by 6 grams or so. We are using much lighter weight antenna wire and fishing line than on the previous flights. This change will give us the additional 5,000' feet or so, we think. The lighter wire requires some serious thought about stress on the mounting points and the soldered attachment to the PCB. Dean has a stress free design in mind which we will incorporate this time. He is an aeronautical engineer and comes up with some interesting ideas. Currently, we plan to wait until after January 15, 2021 to have a more favorable sun angle. You have to think of everything in this hobby but that is what makes it interesting.
Third flight and future plans content media
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Donald Giles
Oct 19, 2020
In Show off !
ON Sunday, 18, October at 14:00z we launched our second attempt at a PICO balloon flight. The launch was perfect since it was quite still but at about 1,000' we caught an easterly blowing wind and the balloon took off due east and has not stopped since. The data indicates that it is in the middle of Alabama today and still on a due east path. After being off all night, the transmitter came on at 14:20z this morning and has been flawless since then. We are using Chinese clear party balloons that are 36" diameter. We modified the solar panel mounting by adding styrofoam to the bottom and controlling the angle with the B- connection leads. It seems to work very well. The Zach Tek Pico transmitter is doing exactly as it is supposed to do. LU7AA website converts the power field into altitude in meters. That comes in handy. We have picked up 10,000' in this flight vs. the first one. We have "real" helium now and not the party balloon helium/air mix which limits the attainable altitude. All in all this experiment is going well. We have 3 more transmitters and plan to make slight changes to improve our performance and reach 25,000 to 30,000'. WSPR net call sign: KM5XK APRS.fi call sign: KM5XK-12 Don, KM5XK
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Donald Giles
Oct 12, 2020
In Show off !
AL7CR and I, KM5XK, launched our first attempt on Saturday morning and now two days later it is probably in Canada near Hudson's Bay. (It is not awake yet) The clear Chinese balloon carried our PICO transmitter only to about 10,000' (3,000 m) due to the fact that our helium is the poor variety party balloon air/helium mix. It is hard to find the good stuff in our area. The balloon rose from central New Mexico and went SE into the next grid square then it turned north and crossed I40 into DM75 where we lost contact. We thought it was a goner but the next day it came alive and indicated that it was in the Dakotas and headed for the border. The wind prediction maps show that it should be at the top of Hudson's Bay today then travel south back into the USA near Maine. We are tracking with LU7AA in Argentina and, of course, WSPR net. We thank Harry for his efforts with this product. It gets the job done.
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Donald Giles
Feb 17, 2019
In Show off !
While commissioning my LP4 board I thought it might be convenient to have a truth table that reflected the status of the control circuits for each LPF position. Here is what I came up with. Q1 Q2 R1 R2 R3 LPF-A 0 0 0 0 0 LPF-B 1 0 1 0 1 LPF-C 0 1 0 1 0 LPF-D 1 1 1 1 1 Q1=pin 7 on J4 Q2=pin 8 on J4 I know this is elementary to most users but, for me, having a schematic and truth table saves some time when tracing the signal paths.
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Donald Giles

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