U3S18 may have finally met it`s fate with Hurricane Jose storm system.
So far, about an hour behind startup time.Bit again,anything is possible today but unlikely.
Even went as far to find a visual of weather conditions in the general area.

Says very little but better than nothing.

Again,not too sure if this will be accurate.Had to leave late in the day and ran this trajectory from 3 hour old data.
It has not moved much anyhow so probably close enough.
All only if it survives tonight.

I wish to connect an external DAQ chip and associated circuitry to the U3B's onboard Atmel 328 to perform some operations and measurements the 328's internal ADCs can't do (I'm assuming that the U3B will use the same microcontroller as U3S). ?Is there a way to add a piece of user's code that the unit will call periodically? ?If yes, is there a way to save some text containing the data such that it can be incorporated into the transmitted message?

>Why are you using copper wire to solder to solar cells?
I would use wire for this application because it's flexible in more directions. ?I prefer #28 over #30 because it withstands more nicks and bends. ?Ribbon is used to make encapsulated panels because it keeps everything thin and helps keep the circuit from moving around during lamination. ?Fortunately, it's also easy for automated soldering machines to handle, as John B. noted.
Cheers, Halden NR7V

Another note.
Hysplit trajectories seem way off.Not sure why,maybe the hurricane system throws the forecast off?

Thanks Jeff,I see your spotting it on 20m WSPR often.
30m still a bit poor but maybe the solar activity will clear up and give more spots later.

Picking it up here Jim, on 20m... good signal here today.? Last couple days I might spot it once or twice.? Will try 30m for a while and see how that goes.

Hurricane is nearby but hoping like Harvey during the first few days,it will get pushed away.Need to avoid storms yet.
Trajectory for the next 48 hours -

?	?	?	?	?	?	?	?	?	?	?
?	?	?	?	?	?	?	?	?	?	?

On 9/17/2017 2:26 AM, John Backo via Groups.Io wrote:

Why are you using copper wire to solder to solar cells?
Easily available is thin 1/4" wide copper

The issue I see is not the wire, but getting the cell to take solder. Once the cell tins, anything will solder to it. Copper strips are likely made of copper wire that has been rolled flat and the thin wire is not a problem to solder to, at least that's my experience.

I'll try using some extra rosin flux carefully. I note that the flux from rosin core solder spreads out onto the surface of the cell. I hope I'm not "poisoning" the cell when this happens. I'll try to do some before/after measurements

John K5MO

7 full days in the air,6 nights.
One hour later than predicted,U3S18 gets the very first spots on 30m.

?2017-09-17 12:14?	?N2NXZ?	?10.140148?	?-24?	?0?	?FM83?	?0.01?	?N2NOM?	?FN22bg?	?1488?	?315?
?2017-09-17 12:14?	?N2NXZ?	?10.140147?	?-29?	?0?	?FM83?	?0.01?	?K9AN?	?EN50wc?	?2343?	?296?

John's suggestions are good.

Search eBay for solar cell tabbing wire, it's not expensive, is pre tinned and fluxed.

Search youtube for solar cell soldering - you will find many (many) videos on the subject.

But, always use flux, be generous, it can be cleaned off with alcohol and generally recommended is solder containing some silver and use a higher temperature for soldering than you usually would (for those with adjustable soldering irons), silver in your solder requires it and solar cells conduct heat away quite well so the higher temperature is required to reduce your soldering time and to keep enough heat where you need it to complete your joint.

cheers, Graham ve3gtc

"What seems to work for me is to apply a tiny bit of flux to the cell, then melt some solder onto my wire (I would use #28 gauge here)."

Why are you using copper wire to solder to solar cells?

Easily available is thin 1/4" wide copper, tin, tin-plated copper, and
silver strips in any length. They are used by professional solar panel makers
because they are MUCH EASIER to work with than wire.

Gauges vary, but 30 gauge is easily available.

Where to find? E-bay has them in lots of sizes. I found some very good
25' rolls in Hobby Lobby. Both copper and silver (usually in the stained
glass department).

Maybe a bit more expensive than wire, but still reasonable, and , as I have learned,
much easier to work with on solar cells. They do weigh a bit more than wire, but not much.

john
AD5YE

Thanks all for sharing how you're making your PV arrays and antennae! ?I haven't flown a balloon yet, but I work with solar cells a lot. ?Here's how I plan to make my first balloon array:
1. ?I'll dice the cells by digging a trench with a dremel(tm) cutting wheel from the back. ?Then I'll break the cell. ?Fracture should cause fewer shorts at the pn junction than a sawed edge will. ?The pn junction is at the front of the cell.
2. ?I'll measure the I-V curve of each diced cell under simulated sunlight and reject any with a fill factor (FF) less than 70%. ?FF is Vmp * Imp / (Voc * Isc) (mp means maximum power point, the pair of I-V points that give the highest I*V product). ?I'll set the light intensity so that Isc is approximately 40 mA/cm^2 * the cell area for this test.
3. ?I agree the cells are hard to solder to. ?What seems to work for me is to apply a tiny bit of flux to the cell, then melt some solder onto my wire (I would use #28 gauge here). ?Then gently press the blobbed wire to the fluxed spot and touch it with the soldering iron until it yields, very much like what Mikael wrote. ?It's best to minimize the amount of time the solar cell is hot. ?I'll test each cell after soldering to see whether the soldering ruined it.
To gather power earlier in the morning and later in the evening, I'm thinking of making a dual array on a folded surface, shaped like a gable roof. ?I'll measure the I-V curve of each subarray in partial darkness to determine whether the dark array will absorb current from the illuminated one, and if it will, install a schottky series diode with each sub-array to prevent such losses. ?Has anyone else already gone down this road?
Awaiting U3B,
Halden NR7V

开云体育

Thanks for the arrivals info Lee!

Hope you enjoy the kits! Any difficulties, bugs, etc - please let me know and I will sort it out.?

73 Hans G0UPL

On Sat, Sep 16, 2017 at 3:28 AM, Leland L. Bahr <l@...> wrote:

My three QCX kits, 281, 282, 283 arrived in today's mail.
Lee, w0vt
Coldspring, Texas

Dear all
After alignment all seems working properly receiving incoming signals from the band but an audio more or less 1 kHz is present all the time .... other question is that I'm having with 12 Volt only 0,3 W on a 50 Ohm dummy load.
Any of you guys can give me a hint ?
Thanks
Carlos
Enviado do meu iPhone

The balloon may have gone down but here is where it should be according to the last spot. I think if it will show up it could be on the 16th just after sunrise or near sunset on the 17th. ?north west of Japan

I have never used any battetries on my flights, they have all been solar only so I cant say anything in that regard.
In the picturs released on the beta u3b there looks to be some sort of solar charger on the pcb so thats probably already been taken care of, we?ll see if Hans have any input on the mather or we will se the day its up for sale.