Date   
Re: QCX party on Monday 27th May #qcx #qrp-dx

Peter GM0EUL
 

I did better on 40m at 1900z.  Worked two qcx/qcx qsos with Eric F5JKK and Jens DG2FDD.  Then a few minutes after the end of the session Martin called me (qrp/qrp), not a QCX but a very nice signal.  Then a couple of others but running 150 and 100 watts.

I tried calling LX/GM0OBX, who was dominating the World on 7031.9, but I couldn't remember how to get my QCX to split.  I think I was doing it right, I had both VFOs displayed but I'll need to read the manual again to make sure.  

I won't stay up for the 0300 (0400 local time here which I consider the middle of the night!)  I'm sure I'll meet some of you over the next few weeks on other activities and see you all for the next party in June.

73, 
Peter GM0EUX

Re: QSX Linear Amp BS170 Heatsinking

ajparent1/KB1GMX
 

There is nothing wrong with insuring the heat is conducted away.

However a point of note, they are not getting all that warms unless you
are driving them to excess...  However the output of the amp will be well into
the nonlinear region.
At 10W out the drive is maybe 350mw at 14mhz.

Allison

Re: Two problems with QCX 20: 'ringing' and mechanical sensitivity #problem

ajparent1/KB1GMX
 

Kevin,

Check your soldering.  You ahve a weak or cold joint or maybe one that is not
soldered at all.

The radio has no issues with microphonics (mechanical vibration of the board)
is the joints are good.  

Allison

Re: Two problems with QCX 20: 'ringing' and mechanical sensitivity #problem

Ronald Taylor
 

Kevin, one place to start looking is the solder connections to the volume pot. These are notorious for not being properly soldered to the board. Good luck

Ron

On Mon, May 27, 2019 at 16:22 ajparent1/KB1GMX <kb1gmx@...> wrote:
Kevin,

Check your soldering.  You ahve a weak or cold joint or maybe one that is not
soldered at all.

The radio has no issues with microphonics (mechanical vibration of the board)
is the joints are good.  

Allison

Re: Where can I buy floater balloon?

Joe Street
 

I agree with Bill,

This subject is getting old!  But, to answer a direct question of my post, aluminization will certainly slow the diffusuion of gas.  The deposition of metalic and various other thin films is a subject I have long experience with.  In this case the diffusion of gas through the stackup of materials is not the only consideration but such films are typically riddled with microscopic pinholes and stress cracks which would make it impossible to quantify in any meningful sense except to say that metalization would certainly help at the penalty of adding weight.

" Permeability is a function of electron cloud size, not a function of the mass of the molecule
as was suggested by one post in this thread.
(An H2 molecule has an atomic weight of 1+1=2, a helium atom has an atomic weight of 4.)

Jerry, KE7ER"


I refer you ro Grahams Law.  You can look it up.


ve3vxo ...out.

On Mon, May 27, 2019 at 6:27 PM Jerry Gaffke via Groups.Io <jgaffke=yahoo.com@groups.io> wrote:
That is indeed a very nice fact sheet on mylar.

Figure 2 on page 3 shows that  the permeability of hydrogen drops from 200 to 40 cc
of gas per 100 square inch of mylar surface area over a 24 hour period
when the temperature drops from 50 C to 0 C.
This is when going through a 1 mil (0.001 inch) thickness of mylar 
with a pressure difference of one atmosphere.  

The rate of gas loss will be linear with time and surface area. 
I assume that it would also be linear with pressure difference.
But figure 2 makes clear that the permeability drops off logarithmically with temperature.
Figure 1 shows the effect of mylar thickess on permeability, which appears to also be logarithmic.

From the graph for hydrogen we see that for a drop in temperature from 50 C to 0 C,
the permeability drops by a factor of 200/40 = 5.   
Since it's logarithmic, any drop in temperature of 50 C will cause a factor of 5 decrease
in permeability.  For a drop in temperature of 25 C, the permeability drops by sqrt(5) = 2.236
And in the general case, for a temperature change of dTemp degrees C,
the permeability changes by a factor of  5 ** (dTemp/50)
(where ** means raise it to the power of, for example 10**3 = 1000)

In Mikaels case, the temperatures we are interested in are the 20 C inside the house,
and -50 C at 10,000 meters of altitude.  A dTemp of  -70 C
So the permeability changes by  factor of 5 ** (-70/50) = 0.105
and the mylar balloon at 10,000 meters has around one tenth of the permeability
of the mylar balloon left inside the house.

All lines in the graph of fig 2 have about the same slope, so while I created that formula
from numbers read from the line for hydrogen, it will also apply to other gasses
such as helium.

Also of note, at 0 C the graph shows a permeability for hydrogen of around 40, 
the permeability of helium is around 67.   This is because two hydrogen atoms
form a molecule of H2, whereas each atom of helium travels alone allowing it to 
sneak through smaller openings in the membrane, as noted by several posts in this thread.
Permeability is a function of electron cloud size, not a function of the mass of the molecule
as was suggested by one post in this thread.
(An H2 molecule has an atomic weight of 1+1=2, a helium atom has an atomic weight of 4.)

Jerry, KE7ER



On Mon, May 27, 2019 at 12:46 PM, Joe WB9SBD wrote:
Hi Joe,

Nice fact sheet. I wonder how much the effect of the Aluminum helps block permeability, and does it vary also with temp?

I printed out that chart, and gonna try to interpolate the chart more to the left and the temps we experience during flight.

Joe WB9SBD

The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com
Hide quoted text

 

On 5/27/2019 1:01 PM, Joe Street wrote:
Hi Jerry
 
Diffusion is a very fundamental property in nature and the temperature dependence is well known but you can find the specific properties of mylar with a simple search.
 
 
Best regards
Joe

On Mon, May 27, 2019 at 12:28 PM Jerry Gaffke via Groups.Io <jgaffke=yahoo.com@groups.io> wrote:
Joe Street wrote:  "The diffusion rate of mylar is temperature dependent and decreases with temperature."

Do you have a source for that?
If true, that answers the question Mikael had in post 34692.
The question that, for better or worse, kicked off this rambling discussion of buoyancy.

Jerry, KE7ER

QCX party on Monday 27th May - 1900Z

WB5BKL
 

QCX-20 to a 40M extended double Zepp via a T1 tuner. Did not try 40M.

One non-QCX.

Also heard (but not worked) W5BW(?) and WB3KLI. Hope to try again tonight. Had fun.

cln - Nick
WB5BKL
Lake Buchanan, TX

Re: Where can I buy floater balloon?

Jerry Gaffke
 

Curiouser and curiouser.

Here's what looks like a college undergraduate chemistry text with a discussion of Graham's law.
In the exercises for the student at the end of the section, exercise #1 uses Graham's law
to find how much faster hydrogen would leak from a party balloon than helium.
  https://opentextbc.ca/chemistry/chapter/9-4-effusion-and-diffusion-of-gases/
And another:
  https://au.answers.yahoo.com/question/index?qid=20061209172707AANley3
And another, this one using Graham's law to compare hydrogen with neon:
  https://www.dummies.com/education/science/chemistry/how-to-solve-diffusion-and-effusion-problems-using-grahams-law/

Here's a PhD in fluid dynamics who says that helium leaks faster than hydrogen from a party balloon
    https://www.quora.com/Does-helium-diffuse-faster-than-hydrogen
Search for the word "party" to find that discussion.
He attributes this to the size of the molecules.
His conclusion agrees more or less with what we see in figure 2 of the mylar spec sheet
    https://usa.dupontteijinfilms.com/wp-content/uploads/2017/01/Mylar_Chemical_Properties.pdf
which is why I went with molecular size in my previous post.
 
Note that some of the texts use the word "diffusion" for molecules passing through a membrane 
or small hole, others call this "effusion" to make it distinct from diffusion of gasses in an open space.
The meaning is usually clear from the context.

Here's where it gets really curious, a quote from the Journal of Chemical Physics:
    https://aip.scitation.org/doi/abs/10.1063/1.1750133
where they discuss the diffusion of helium and hydrogen through pyrex:
"At 512°C the rate of helium diffusion is approximately 45 times that of hydrogen, and it is believed that chemical forces delay the progress of the hydrogen molecule through the silicate network."

My best guess is that the "chemical forces" involved have to do with the fact that an H2 molecule is polar and helium atoms are not.
Perhaps mylar also has polar molecules that interact with hydrogen, allowing helium to escape faster than H2 as per the spec sheet.
Some materials other than mylar (and pyrex) may not have this property, and thus follow Graham's law.
Could be worthy of experimentation.

This is now way above my pay grade, and long past time for me to park it.
If anyone has additional insight but is hesitant to post to the forum,
feel free to respond to this via private email to jgaffke at yahoo

Jerry, KE7ER



On Mon, May 27, 2019 at 05:02 PM, Joe Street wrote:
I refer you ro Grahams Law.  You can look it up.

Re: QSX Linear Amp BS170 Heatsinking

Hans Summers
 

Hi Robert
 
I hope Hans will comment and tell us what he thinks of what I have done (but thanks for your and Klaus's comments as well!).

The blue silicone pads were included in the kit because the IRF510 tabs are Drain (not Source) so are RF-hot and may not be bolted directly to the grounded heatsink. They are therefore used for their electrical insulation properties not their heat conducting properties. Indeed I am not convinced that the silicone pads will improve the thermal situation; they add a little thermal resistance of their own. But this is nothing compared to the thermal resistance internal to the BS170 between junction and the plastic surface. So whether the flats of the transistors are laid flat on the board, or the pads are used, I don't think it is going to make much practical difference to the heat transfer between the transistors and the heatsink. 

The piece of silicone pad between the large washer and the curved tops of the face-down BS170s wasn't for heat transfer either - it was just to hold them securely and to some extent spread out the pressure of the bolt compressing them against the PCB rather than all the force being applied to a single contact vector on the curved surface of the BS170s. 

I don't think there is any harm in what you did. But neither am I convinced there is benefit either... my feeling is that it just won't make any difference!

73 Hans G0UPL

Re: QCX party on Monday 27th May - 1300Z

Hans Summers
 


Hi Peter
 
I could see quite a lot going on on the RBN band map but only heard a couple of stations on 20m and 40m.  Off to a very good start when I first switched on I heard EA7/ON7DQ calling cq.  He was weak and difficult to copy 319, but he heard me and managed a basic qso on 20m.  Luc, Jaen in Spain using a QCX running 5w to (I think) a long wire.  He gave me a 519.  That's over 1246 miles (2006 km) QCX to QCX.  What's the record for a 2-way qcx call?

I don't know the record but my personal best QCX-QCX is G4GIR at 1771 miles (2834 km). 

Radios operated here are QCX-20 and QCX-40. Antenna is OCFD http://hanssummers.com/404ul

Here's a list of all my 2-way QCX QSOs. QCX both ends, no more than 5W each end; several stations were worked more than once, on different occasions; sorted by decreasing distance:

Name    Call   miles   km   Band
------  ------  ----  ----   ---
Ian     G4GIR   1771  2834   40m
Klas    SM6JWR  1625  2616   40m
Luc     ON7DQ   1605  2583   20m
Jose    EA2KV   1600  2576   40m  (2 times)
Andrey  R1CF    1591  2561   40m
Joop    PA3JD   1527  2457   20m
Eric    F5JKK   1329  2139   40m  (2 times)
Andy    DM5MU   1281  2061   40m  (2 times)
Jiri    OK1DXK  1101  1772   40m
Zdenek  OK2BQN  1017  1637   40m
Alex    9A3JH    946  1523   40m

My best DX (not a QCX at the other end) with my bareback QCX-40 with 5W output, is Tad JH1HDT at 5,788 miles (9,261km).

Needless to say, but will say it anyway... in my opinion, QCX's ROCK!
 
73 Hans G0UPL

Ultimate 3 Error: 0 Power

Adrian Rees (MW1LCR) <mw1lcr@...>
 

Hi all
I have resurrected an Ultimate 3 transmitter as I want to use it for an experiment. Upon powering it up I get the message:

Error 0: Power 

On the display. The firmware is Version 3.09c (quite dated I guess) and I have it configured for WSPR.

Any suggestions ?

Thanks
Adrian M1LCR

Re: Ultimate 3 Error: 0 Power

Alan G4ZFQ
 

I have resurrected an Ultimate 3 transmitter as I want to use it for an experiment. Upon powering it up I get the message:
Error 0: Power
Adrian,

The manual will probably tell you. My guess is that you have not set the power figure in WSPR correctly.

73 Alan G4ZFQ

Keyer lags and hangs sometimes #qcx #problem

DG2FDD
 

Hi all,

yesterday during the QCX-challenge, I noted that the keyer in my QCX40 seems not to work as it should: First, there seems to be a short lack between keypress and beginning of the beep (only in the range of 1/100th sec, barely noticeable, but still, I can "feel" it). Second, sometimes, the dit or dah comes quite a lot to late (at least a dit-length), just as if it was buffered and then played out.

My first guess was that maybe the S-meter generates a kind of timeslot for polling the state of the paddle, but deactivating the S-meter in the menu lead to no change. Second guess: bad contacts in the paddle. Cleaned them thoroughly (paper and contact solution). But that was not the problem – on a different trx (mchf), the paddle produces fault-free dit-dahs. I am not sure, if the QCX keyer always behaves like that, since it was my first serious use of it – straight key user until two-three weeks :-)

Anyone of you observed similar issues? Hints?

73 de Jens, DG2FDD

Re: #pa #u3s Extreme power curve across the bands. #pa #u3s

Hans Summers
 

Curt, Arv

I don't think there was a "widespread issue" with QCX kit capacitors. That's a bit of an exaggeration. There were some instances of capacitors which appeared to be a bit lossy, this seemed limited mainly to the 390pF capacitors in the 20m band version's LPF though I also suspect a few of the 560pF in the 30m version too. 

There were, generally, a small number - bear in mind that there are 7,496 sold QCX kits and we do tend to hear on this group, about the small percentage that don't work or that don't work as well as they should. 

There are several reasons for low power output. These include inaccurate dummy loads and inaccurate power measurement. In cases where the power really IS too low, by far the most common cause is the inductance values being too high. This can occur due to component tolerances (capacitor values and core permeability) but the most common cause is winding style. I recently added some information about low power output to the QCX FAQ http://qrp-labs.com/qcx/qcxfaq#lowpower . In most cases fiddling with the inductance values is what is needed, NOT replacing capacitors. People who go to replace the capacitors straight away are quite likely to be disappointed. One sign of lossy capacitors is when on key-down, the power output appears to rise slightly over the course of a second or two. 

73 Hans G0UPL

Re: #pa #u3s Extreme power curve across the bands. #pa #u3s

Nik
 

Hans,

I've noticed that the power output curve "dips" at 20m and then rises for 17m and 15m.  Is this what you would expect?  I've double checked the 20m lpf and rebuilt it and the results are the same, although I've used the original components.  I'm going to change the capacitors as a last resort (preparing myself for a disappointment).

This sort of tinkering is why I am an Amateur.  Hands on puzzles are great.

Looking forward to building your next kit.

Nik M1DOX

Re: QCX party on Monday 27th May - 1300Z

Don
 

QCX-40: Worked all three time slots from here in FL with my pretty compromised (HOA) antenna but, ... no joy here either.  
My trusty friend RBN heard me best in the late evening slot but sadly (a) nobody else nor (b) did I hear any of the familiar calls shown on the RBN Cluster (A Wonderful Innovation!).  Thought sure I'd hear Nick in TX but the "RF SHIELD" was apparently up in force here yesterday.  Maybe next time.
... 72 ... Don K3RLL

Re: QCX party on Monday 27th May - 1300Z

Lloyd K3ESE
 

yesterday was my first time participating, with my 20. I worked the first two, not the third, as I had to go off to play Irish music with the xyl.

I had a fine time, and in the second session, I worked 2 QCXs, and DX! ESP and FRA.

when my 40 returns from its holiday in Turkey, I guess I'll be juggling them both, on the Last Mondays.

Re: #pa #u3s Extreme power curve across the bands. #pa #u3s

Curt M.
 

Hi Hans, that was my mistake in using the term "wide spread".  That's what I get for trying to do a couple of things at the same time therefore getting my terms mixed up.  i guess at the time I was thinking of wide spread meaning something that is not very common and as I currently type these words I'm trying to think of the term for something not so common and I keep going back to wide spread.  Maybe it would have been best said, "there was a rare occurrence that some capacitors for the 20m filter were not up to spec".

Anyway, I knew what I wanted to say, just didn't say it correctly so I apologize for messing that up.

Curt M.

Re: QSX Linear Amp BS170 Heatsinking

rentwist@...
 

Thank you Hans and Allison for your comments!  I am impressed with the amp 's performance thus far (only had 10 dBm available from my bench Sig Gen), its compactness (especially since it uses leaded parts) and (of course) the price!  Well done.

I don't know if you are aware but the amp works very well as an amp for the Radioberry SDR and this is why I bought a second one to have on hand.

Finally, I would just like to express an opinion (which is sure to be an unpopular one).  When I build your kits, I am always imagining how small, compact and neat the design would be with SMT parts.  Some of us (but far from the majority I'm sure) that are comfortable with SMT assembly wish for such things.  Having said that, I am grateful to have your wonderful products available to me regardless of what component technology they use!

73,

Robert, WA2T

0300z QCX Party-Load of fun

Brian N7BKV
 

So you know, I am 65 years old and been a amateur op less than a year.  Got into radio to do QRP CW.
Understandably my on-air practices are far from polished, so forgive me for not executing the clearest code and tightest protocol.

My QTH is California, central Sierra near Yosemite National Park.

Contacts during the party 40m only:

WA6OUW, Don in Redding (northern) California  96 miles, 156 km
VA7ADI, Adrien in Abbotsford, BC  781 miles,   1258 km

Far as I know from my notes both were working QCX.

There were many others calling me back, but on at least three episodes there were mulitple QCX party stations,  numerous other ops trying to get a California contact, and massive QRN.

So please forgive my on-air feebleness if I failed to acknowledge you.  If you were trying to get through, please let me know.  And if you can recall, help me with a signal report.

And if you recall even hearing me, let me know.  And if you want to set a sked for a more sane moment, let's to it!

Thanks much.  It was intense fun.  But working 7030 at 0300z is like trying to find  your cousin at Times Square on New Years Eve.

Thanks so much to Hans and Peter for making this all happen.

73
Brian N
N7BKV
radio1@...

Re: 0300z QCX Party-Load of fun

Gary Bernard
 

I was on 40 in the third time slot. Worked W0ITT also QCX and heard WA6OUW,N7BKV and a N5. I called all of them but the QRN was terrible. If they responded I wasn't able to copy.
73, Gary W0CKI


-----Original Message-----
From: Brian N7BKV <cl@...>
To: QRPLabs <QRPLabs@groups.io>
Sent: Tue, May 28, 2019 7:48 am
Subject: [QRPLabs] 0300z QCX Party-Load of fun

So you know, I am 65 years old and been a amateur op less than a year.  Got into radio to do QRP CW.
Understandably my on-air practices are far from polished, so forgive me for not executing the clearest code and tightest protocol.

My QTH is California, central Sierra near Yosemite National Park.

Contacts during the party 40m only:

WA6OUW, Don in Redding (northern) California  96 miles, 156 km
VA7ADI, Adrien in Abbotsford, BC  781 miles,   1258 km

Far as I know from my notes both were working QCX.

There were many others calling me back, but on at least three episodes there were mulitple QCX party stations,  numerous other ops trying to get a California contact, and massive QRN.

So please forgive my on-air feebleness if I failed to acknowledge you.  If you were trying to get through, please let me know.  And if you can recall, help me with a signal report.

And if you recall even hearing me, let me know.  And if you want to set a sked for a more sane moment, let's to it!

Thanks much.  It was intense fun.  But working 7030 at 0300z is like trying to find  your cousin at Times Square on New Years Eve.

Thanks so much to Hans and Peter for making this all happen.

73
Brian N
N7BKV
radio1@...