Date   
Re: 11. Potentiometer tuning for the Ultimate3

Steve MW0KST
 

Gents, almost exactly the same problem here -  just boxed up my U3S and tried to add pot tuning. The freq only goes up, and control is very severe. I used a 4K7 pot and 470R resistors.

Any update on this would be great.

73 Steve MW0KST

Re: QCX RF Power Ramps Up

 

Mike, if that fails to fix, you may want to look at this and see if it is the issue and solves it: http://qrp-labs.com/qcx/qcxmods.html#pa

Re: Internal RF power probe not working?

 

I used antenna matched at 50 Ohms, BUT, since I found PA transistor(s) blown as well as part of IC3, I am awaiting IC3 part to fix, then I will see if it works as the 50mW could have thus been a correct reading!

Re: QRC WSPR Beacon Mode Decode Issue

Alan G4ZFQ
 

I decided to look at the signals with "Argo" to see how the shifts look, see below for results.
What controls WSPR shifts?  I assume that shift control is in software
Chris,

That looks about right although the CQX has those long unshifted lines. Looks strange, is it like that on every transmission?
The shift is all in the firmware.

73 Alan G4ZFQ

Re: QCX RF Power Ramps Up

Alan G4ZFQ
 

My 30 meter kit is up and running.  Have made some fun QSO’s and WSPR reports.  I notice that the RF power output ramps up on keydown from about 2 watts to 3 watts over a period of about 3 seconds.
Mike, Others have noticed this, it is possible that it is caused by mismatch due to high inductance in the LPF. Try a turn off L1, 2, 3 or maybe two if an improvement is noticed.

Some have changed the capacitors but they are good quality and have not been replaced in isolation. At the same time they reduced the turns.

73 Alan G4ZFQ

QRC WSPR Beacon Mode Decode Issue

Chris Kovacs
 

Hi All,

I have been reviewing decoding issues threads here as I just completed my QCX transceiver  and installed  firmware 1.0.0d.  The little rig checks out fine except for WSPR beacon mode.

Basically,I am seeing issues with stations not being able to decode  beacon frames.  Only a couple of stations can decode the signal when I've tested on air.  When using my Ultimate 3 WSPR transmitter (300mw), I get over a dozen stations that are decoding.

I set up a local receiver and attempted to decode the WSPR signal from the QCX xcvr.  I had very little luck and only able to decode once or twice.  I then connected the GPS module to see if it changed the symptoms which it did not.

I decided to look at the signals with "Argo" to see how the shifts look, see below for results. 

What controls WSPR shifts?  I assume that shift control is in software and hardware does not come into play, is that a correct assumption? Has anyone else looked at the WSPR signals? 


QCX WSPR  Beacon Mode:




Ultimate 3 Transmitter:




73,

Chris, w0anm

QCX RF Power Ramps Up

n0mpm
 

My 30 meter kit is up and running.  Have made some fun QSO’s and WSPR reports.  I notice that the RF power output ramps up on keydown from about 2 watts to 3 watts over a period of about 3 seconds.  Is this to be expected or is it time to start tinkering?

Thanks,
mike. n0mpm

Re: RF Output

Marc Katz
 

Looks good

Tnx Mike

Marc WB2MSC

On Nov 10, 2017, at 11:31, Michael Lloyd <mikell@...> wrote:

These guys are a good source of QRP antenna tuners. In the UK. I've bought some of their kits and I'm in the US

https://www.sotabeams.co.uk/

73
NE5U

Mike

November 10, 2017 at 9:37 AM
Great idea!

They make “Antenna Tuners” for mobile use and they’re not too costly.

Have to look around beginning with the site you mentioned.

Marc






Re: U3S-19 in the air...struggling for altitude

James Zelazny jr <wtfbsyt@...>
 

Halden,
The flight page map vanished on me for some reason.I just tried to fix this but the payload seems to have stopped transmitting.My guess is that the solar angle is not enough to power the system for very long so far up North...at least I hope that is what it is :)
Everything looked fine and it stopped @ 15:48.Looking at the data I see voltages dropped a bit.It will shut down @ 3.49v and was last read @ 3.54v.
Needs to travel South hopefully tomorrow.
I used 4 balloons as they are new types I like very much,but undersized.Tried only 2 on my last flight and only achieved 4000m and felt 4 will help a bit more in this regard.Seems to have added just over 1000m which is better but not great.My choices were slim with balloons since I think Qualatex have declined over the years.These 29" balloons are 1000 times better quality and rather chance low altitude flight over a complete failure.Losing payloads to poor balloon quality makes no sense to me.The data uploads is using the special firmware in which I am not able to help with.I think you will need to wait for Han`s U3B`s to become available before obtaining this firmware.Best bet is to ask for more info here.The people there have many methods for tracking - http://webchat.freenode.net/?channels=highaltitude
Most are using this site for tracking balloons - https://tracker.habhub.org/#!mt=roadmap&mz=5&qm=1_day&mc=53.46751,-9.26514
There is a site if you want to try payload stuff,but they are nothing like what the U3B will be once available.You may find this fun to play around with.
http://radio-signals.com/forum/
Jim

Re: How hot should that 7805 be?

Barry Mercer
 

Thanks for this.   I’ve already attached a heatsiink to the component to help with heat dissipation. Knowing it’s good to 125C makes me feel much better ... maybe if I get a teeny weeny kettle, I can brew a cup of coffee while WSPR does it’s work. 

Barry 

Re: Discrepancy in the manual regarding L4

Hans Summers
 

Hi Jim

L4 is T37-2. Thanks, I will correct the error in the manual. 

For reference:

The 37 or 50 refer to the toroid (outer) diameter in 100's of an inch; so 37 means 0.37 inches (9.4mm) and 50 means 0.50 inches (12.7mm). 

The -2 and -6 refer to the material mix. -2 cores are painted red, -6 cores are painted yellow.

In the QCX kit:

L1, L2, L3: T37-6 (40, 30, 20 and 17m versions); T27-2 (60 and 80m versions)
L4: T37-2 (all versions)
T1: T50-2 (all versions)

73 Hans G0UPL 

On Nov 10, 2017 18:45, "Jim Sheldon" <w0eb@...> wrote:
After section 5.10 of the construction manual (theory of PA operation) was called to my attention yesterday and carefully reading that section again, I noticed that L4 is mentioned there as a T50-2 core while in the actual construction section it's listed as a T37-2 as are L1, 2 and L3.  Is this a typo in 5.10 or is L4 really supposed to be wound on a T50 sized core?  I'd think the larger core would definitely interfere with the underside of the LCD display board.

W0EB

Re: RF Output

 

These guys are a good source of QRP antenna tuners. In the UK. I've bought some of their kits and I'm in the US

https://www.sotabeams.co.uk/

73
NE5U

Mike

November 10, 2017 at 9:37 AM
Great idea!

They make “Antenna Tuners” for mobile use and they’re not too costly.

Have to look around beginning with the site you mentioned.

Marc






Discrepancy in the manual regarding L4

Jim Sheldon
 

After section 5.10 of the construction manual (theory of PA operation) was called to my attention yesterday and carefully reading that section again, I noticed that L4 is mentioned there as a T50-2 core while in the actual construction section it's listed as a T37-2 as are L1, 2 and L3.  Is this a typo in 5.10 or is L4 really supposed to be wound on a T50 sized core?  I'd think the larger core would definitely interfere with the underside of the LCD display board.

W0EB

Re: Internal RF power probe not working?

Marc Katz
 

Did you use a dummy load? Hans taught me that that’s the only way to get an accurate reading. Unless your antenna is right on at 50 ohms then the reading will be off like mine was. Marc

On Nov 5, 2017, at 04:10, VK5EEE <vk5eee@...> wrote:

I did try using it with, as advised in the manual NOT to, the DC shorted for the DVM to read the DC volts. Now I removed that short, and have the probe from Pin 2 to the RF output at the right side of C28. It measures only 0.05W when I transmit. That can't be right as I've been having DX QSO and WSPR to Europe. Could it be that something is damaged in the RF power system? Maybe D4 and/or C42 would have become damaged?

Re: RF Output

Marc Katz
 

Great idea!

They make “Antenna Tuners” for mobile use and they’re not too costly.

Have to look around beginning with the site you mentioned.

Marc

On Nov 10, 2017, at 09:00, Paul Jorgenson KE7HR <ke7hr@...> wrote:

Build (or buy) a matching circuit (some call them antenna tuners when they are really just impedance matching circuits). It will keep from abusing the final amplifier with high reflected power.

Maybe start at: http://www.qsl.net/wb3gck/tuner.htm

Then, branch out from there. High SWR is not an insurmountable problem.

---------

Paul KE7HR


Re: U3S-19 in the air...struggling for altitude

HF
 

Congrats, James!
I'm trying to learn as much as I can about pico HA floater balloons while I await the U3B's debut.
1.  Why 4 balloons for only 9.5g payload? An experiment of some sort, but I wonder what. (Q for James)
2.  My Chrome browser no longer displays the qrp-labs tracking maps for any balloons (stopped working a few weeks ago), but IE will display it for some but not this one.  The text update for U3S-19 appears in the map window on both browsers.  Has something changed in the way the qrp-labs tracking site displays the maps?  What adjustment do I need to make in my browser settings? (Probably a Q for Hans)
3.  U3S-19 link doesn't appear in the list of balloons on the qrp-labs tracking site.  Just a minor inconvenience.
4.  Once ready to launch a balloon, how does one arrange for its data to appear on the qrp-labs and/or aprs.fi tracking site? 
Halden NR7V

Re: U3S-19 in the air...struggling for altitude

James Zelazny jr <wtfbsyt@...>
 

Nice trajectory in my opinion should it be accurate -

Re: Power output on 20 meters.

Daniel Ekman SA2KNG
 

On Fri, Nov 10, 2017 at 7:31 AM, John PD7MAA <pd7maa@...> wrote:
I used the mod by DJ2QV.

The lower C33 was a workaround of the real problem, described here: http://qrp-labs.com/qcx/qcxmods.html#pa
It would be nice to know if this fixes it in your unit, as well as recovering some gain in the receive path.

Re: U3S-19 in the air...struggling for altitude

James Zelazny jr <wtfbsyt@...>
 

Alive and well.
Altitudes are best since launch @ over 5100m with speeds increasing.Heading North to North East and like this trajectory a lot.This is much better than flying over the mid Atlantic where clouds are more dense with storms.With such low altitudes,it will need a lot of luck keeping above clouds.I think the cooler North will help much better in this regard.But not an expert with this theory.
N2NXZ-11 - https://aprs.fi/#!mt=roadmap&z=5&call=a%2FN2NXZ-11&timerange=86400&tail=86400
Jim,N2NXZ

Re: RF Output

Paul Jorgenson KE7HR
 

Build (or buy) a matching circuit (some call them antenna tuners when they are really just impedance matching circuits). It will keep from abusing the final amplifier with high reflected power.

Maybe start at: http://www.qsl.net/wb3gck/tuner.htm

Then, branch out from there. High SWR is not an insurmountable problem.

---------

Paul KE7HR