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Re: At what point is U3S fully calibrated

Alan G4ZFQ
 

wspr will cope so long as you stay away from the band edges, QRSS needs more stability so ideally needs the TCXO
It depends when the drift occurs Peter.
If the drift is more than about 4Hz during a TX period that is borderline for WSPR. The TX time is when heating may affect frequency. I've no idea how much drift affects QRSS?

Long before the TCXO was introduced there were many ways people used to stabilise the crystal. Many posts about methods and references like http://www.qrp-labs.com/images/appnotes/AN001_A4.pdf

73 Alan G4ZFQ


Re: At what point is U3S fully calibrated

M0PWX
 

Have you done the TCXO mod? Or just using the std 27mhz XTAL as the reference oscillator?

 

This message shows how much the XTAL drifts FW: Upgraded my U3s with TCXO :) (groups.io) even when the GPS module is added for calibration

 

Whether you can live with the drift depends on what signal you are TX, wspr will cope so long as you stay away from the band edges, QRSS needs more stability so ideally needs the TCXO

 

For the mod look at this message Upgraded my U3s with TCXO :) (groups.io)

 

The part you need is QCX+ TCXO (qrp-labs.com) you will need to either buy a spare SIS SYNTH Si5351A synthesizer module kit (qrp-labs.com) or be able to rework your existing board by removing the 27mhx XTAL and C2 (0.1uf cap) then solder a new cap onto the tcxo board then solder it through the holes where you removed C2 from, then add the link wire as in the post

 

NOTE:- the TCXO runs at 25mhz so you need to change the ref freq from 27mhz to 25mhz in the menu’s of the U3s

 

73

Peter

M0PWX

 

Sent from Mail for Windows

 

From: Alan G4ZFQ

 

> I am still getting .037 after calibration.
> What amount would indicate it’s calibrated?

This is the figure on the left immediately after calibration?
If so it means the adjustment was 37Hz, possibly showing too much drift.
What are your calibration settings?

73 Alan G4ZFQ




 


Re: At what point is U3S fully calibrated?

M0RON
 

Mine usually says "=" after calibration, with 0 drift reported on wspr so I'd say that it's fully calibrated. 
Getting spots on wspr depends on more factors than just a zero calibration though. Have you ever had spots? Are you producing rf? Tx frequency? Tx time slot? If you could provide more information then we may be able to help you. 
Andy 
--
The universe is made up of Protons, Neutrons, Electrons but contains only one M0RON.


Re: At what point is U3S fully calibrated

Alan G4ZFQ
 

I am still getting .037 after calibration.
What amount would indicate it’s calibrated?
This is the figure on the left immediately after calibration?
If so it means the adjustment was 37Hz, possibly showing too much drift.
What are your calibration settings?

73 Alan G4ZFQ


Re: QCX challenge #qcx_challenge #qsoparty

ON7DQ Luc
 

Don't have a QCX on 80m (yet), but would be pleased to give you a 1-point QSO of course.
Post ur qrg on the sked page and I'll be there ...

Fieldday: I'll be operator at ON4OS/P for a few hours on Sunday.
73
Luc ON7DQ


Re: Trimmer tool for adjusting trimmer capacitors

ON7DQ Luc
 

cheap and simple ...
I use a piece of PCB a few mm wide,and abt 10 cm long
remove all the copper, and file the tip to the needed shape
If it wears out, I just make another one ... and I don't have to wait for Amazon or other source to ship it ;-)
73
Luc ON7DQ


Re: Trimmer tool for adjusting trimmer capacitors

Hans Summers
 


Hi all

I *used to* have a nice set of ceramic screwdrivers. However, one by one over the years, they have all either got broken, or lost under the piles of debris and unfinished projects and other miscellany here at QRP Labs HQ... 

Now, I just use a cheap all-metal screwdriver, one that comes in those cheap sets of 6 mini screwdrivers from poundland, dollar store or whatever. It always works fine, never any issues with BPF Peaking (or of course the trimmer resistor adjustments). Why? Because I did all the PCB Layouts such that the metal screw of the trimmer capacitor is grounded. So touching it with a metallic screwdriver has negligible effect (yes proximity of metal to tuned circuits alters them a bit but toroids are inherently largely self-shielding and in practice I have not noticed any proximity-detuning). 

73 Hans G0UPL
http://qrp-labs.com


Re: QCX 50w amp receive problem

Timothy Fidler
 

If Q5 has shorted as you put it then there will be next to no voltage on the drain because of the two 10 k dropper resistors on the way to that drain.

Many people operate the  PA from a separate PSU from the 12 V psu powering the Qcx mini . If that is so there is no guarantee the grounds are at the same ground 
or even that the  PA 's PSU os grounded at all.  If that ground is -2.4 V low with respect to the ground of the  MIni then that  Q5 mosfet would turn on... it all depends on contact resistances and so on because the two psus are nominally inter grounded via the key enable line plug  black wire.  (at the instant before it is plugged in of course they are not necessarily so ).  If you have a PSU for the PA which is a switcher you will often find that infact the ground connection betwen the two is the AC Neutral line and the earthing connection in your house wiring SB.  


THe US may not use the MEN system so  in that case I have not a clue how your house wiring neutral links and so on work. 


Measuring the  0 Volt  line of the Qcx and the PA when powered up and NOT connected with respect to a common known good earth like a copper piping system might show you if there are issues to look at.  In the worst case a zero volt strap between the respective PSUS will ensure continuity of the zero volt line (without the Amp enable cable being in place)  


Do yourself a favour and put  470R resistor in the  active line of that cable. I suggested this to someone else who had a completely different issue.  He ignored me an pulled the power on his PA while the Qcx was powered up and destroyed the Qcx.  I asked him why he ignored that advice  (he had an early revision Qcx mini with the suspect regulator).  His advice was  that he thought that was only for hot plug and hot unplug issues.  I asked him why puling the power on the PA with the Qcx connected was not a hot unplug......

 

 


At what point is U3S fully calibrated?

jrc198820@...
 

Last checked I was getting .037 after calibration.
What amount would indicate it’s calibrated and I should be getting spots?


Re: QCX-Mini doesn't Auto-set time with GPS #gps #qcx #troubleshoot

David (W5CWT)
 

Ok, I may have an issue with my cable. It's not apparently shielded very well. I scoped at the output of the board and got a slightly cleaner signal and a good decode. Still has a number of spikes when the signal switches. I'll try to solder a new cable and see if that helps. 


Re: QCX-Mini doesn't Auto-set time with GPS #gps #qcx #troubleshoot

David (W5CWT)
 

On Wed, Sep 1, 2021 at 01:26 PM, Mont Pierce KM6WT wrote:
On Wed, Sep 1, 2021 at 11:21 AM, Mont Pierce KM6WT wrote:
This is 5v logic, so you need to set your probe to 1x.  You should see 5V or 2.5V per division.
See pics on my previous post #68528 (click here).

My scope is showing 2V per division, and the pick signal is at 5V.

(wish my scope had serial data decoder...  Very Nice).


73
km6wt

 Thanks! So, my probe was on 10x. Changed it to 1x and modified the scale. New photo included below. Still, very noisy and no solid decode by the scope. Haven't cracked open the QCXmini to check IC2 yet.


Re: Trimmer tool for adjusting trimmer capacitors

Jim Allyn - N7JA
 

I'm with the other Jim:   get the ceramic screwdriver set.  I bought mine from ebay, because if at all possible, I will not do business with Amazon.  (Most of you probably know why, if you don't know and would like to know, ask me.)  I saw a set of ceramic tweakers probably 40 or more years ago, but never found any for sale until recently.  The current set isn't as good as what used to be available, some of the tips aren't ground properly, some of the tips aren't set in the handle properly, and that sort of thing.  So what?  Buy two sets if you have to (I did).  I also bought a set for a friend who has a masters in Electrical Engineering, current knows little about RF, but wants to design and market radios.  So I thought I'd save him the trouble of either not knowing about ceramic tweakers, or knowing about them but not having any.  If he ever spends any significant mount of time with cheap plastic tweakers, he'll realize what a favor I did for him giving him this set.


Re: QCX challenge #qcx_challenge #qsoparty

Martin DK3UW
 

Hi Christi and Zdenek, that sounds like a QCX party on 80 m next time.

Next weekend is Field Day time in SSB I will participate with a friend. FT 817 80 m Long Wire and 12AVQ for the higher bands.
I am curious to see how QRP will work in SSB. Using DL0EU as callsingn.


Re: QLG3-enclosure, a work in progress #gps #enclosure

David Fine
 

Roelof,

Going back and looking at the panels I made, you are correct.  I also had the paper laminated before attaching to the front panel.  Haven't done that in a while so my brain was not working as fast as my fingers.  Anyway, it makes a nice looking front face.

73,
Dave, W0DF


Re: Trimmer tool for adjusting trimmer capacitors

radiostationx
 


Re: QCX-Mini doesn't Auto-set time with GPS #gps #qcx #troubleshoot

Mont Pierce KM6WT
 

On Wed, Sep 1, 2021 at 11:21 AM, Mont Pierce KM6WT wrote:
This is 5v logic, so you need to set your probe to 1x.  You should see 5V or 2.5V per division.
See pics on my previous post #68528 (click here).

My scope is showing 2V per division, and the pick signal is at 5V.

(wish my scope had serial data decoder...  Very Nice).


73
km6wt


Re: QCX-Mini doesn't Auto-set time with GPS #gps #qcx #troubleshoot

Mont Pierce KM6WT
 

On Tue, Aug 31, 2021 at 10:40 PM, David Chenault wrote:
I've added photos. Any suggestions?
Very Nice Scope.

This is 5v logic, so you need to set your probe to 1x.  You should see 5V or 2.5V per division.

Your pic shows it's displaying 200mv per division.  That's what mine looks like if my probe is on 10x instead of 1x.


73
km6wt


Re: Question about customizing the QLG2/QLG2-SE serial data #clock #gps

Mont Pierce KM6WT
 

On Tue, Aug 31, 2021 at 11:57 PM, Alan G4ZFQ wrote:
NaviTrack has that command built in but most of the other commands need it to be used like a terminal program.
It's a little easier than a terminal program.
The text entry box has the command prefix, you add the cmd#,parm1,parm2...  and hit send.
It calculates the checksum for you as it sends it out the serial port.




Before I got NaviTrack running, I created a few dos .txt files with commands and checksums.  Then I just copy a .txt file to the com port from the dos command prompt to send it.  This is actually a bit easier as I don't have to remember the command #s and what parameters to use... 

To calculate the checksum, I used the NMEA Checksum Calculator webpage (click here).


On my setups I am asked when I start the program which, I suppose, is the same as running as Administrator.
That's cool...   Mine does not prompt...  not sure why.  


I have seen no way of saving settings. I do not think a supercap will help, it loses baud rate settings if it is powered on and another seemingly unrelated command is sent.
Yes.  When I send command 115 to select GPS satellites only, it resets the baud rate back to 9600.  It's probably doing some kind of internal reset to clear out unselected satellite tracking data.


Thanks,
km6wt


Re: Trimmer tool for adjusting trimmer capacitors

 


Re: Trimmer tool for adjusting trimmer capacitors

 


--
Julian, N4JO.

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