Date   

Re: U3s Frequency drift / stability #u3s #wspr #problem

JC - EA2KV
 

Hi guys,
Back again,  let me explain the case in a better way.
The drift Im suffering is, as per this technical note: http://qrp-labs.com/images/appnotes/AN001_A4.pdf a "long term drifting",  my drift during transmision is decent.

More in detail:  
Quote from technical note.
  • Ultimate3S transmission sequence is configured such that there is a pause in transmissions at the end of each cycle, during which the GPS 1pps is used to measure the reference frequency of the Si5351A Synthesiser (27MHz crystal) and compute a correction in software.....".
Unquote.

In my case, the "computing correction in software" ocurring with every single calibration, which is normal in order to get the +/- right reference BUT, never stop moving the Ref. Freq value puting finally my TX out of any RX winddow.

Could this issue be a software problem with the ATMEGA??

Tks - EA2KV


Re: GPS Module wanted

Alan G4ZFQ
 

On 14/12/2018 11:54, mike wrote:
Saw this post two days ago and ordered one of these GPS modules. Awesome. Got it working last night after flashing the latest on three QCX's I calibrated them with the GPS. worked perfectly.
Mike,

Yuo may be interested that the VK2828U7G5LF has one of the u-Blox modules that allows you to configure the PPS to be up to about 15 million PPS! https://sites.google.com/site/g4zfqradio/u-blox_neo-6-7

73 Alan G4ZFQ


Re: GPS Module wanted

mike
 

Saw this post two days ago and ordered one of these GPS modules. Awesome. Got it working last night after flashing the latest on three QCX's I calibrated them with the GPS. worked perfectly.

Thanks for the tip!

mike/w1mt


Re: VFO/SigGen questions

N1BUG
 

Hi Hans,

Back in full operation after a few days being sick...

Thanks for the additional explanation.

For the things I am doing, I probably should use full GPSDOs, but
they are expensive. I am considering something between what I have
now and that level.

So if I have this right, 0.1 ppm would be 0.04 Hz at 400 kHz,
divided by 4 in the quadrature LO of my LF receiver for a final
stability of 0.01 Hz at 100 kHz. That would be about an order of
magnitude better than my free running crystal oscillator, a
worthwhile upgrade and good enough for anything I can do with this
particular system.

73,
Paul

On 12/10/18 11:59 PM, Hans Summers wrote:
Hi Paul

In addition to the (excellent) other answers to your question...

The 27MHz reference oscillator measurement is made to 0.01Hz resolution.

But the calculation of the Si5351A registers inherently contains its own
built-in inaccuracies and this is what limits it to 0.1ppm (actually it is
more like 0.03ppm in practice). This could be improved (if there were more
hours in a day). But this is the state of the firmware currently.

You are also correct that the error scales with frequency. But this
includes both the error of the 27MHz ref clock, and the inaccuracy of the
calculation.

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



On Mon, Dec 10, 2018 at 1:42 PM N1BUG <paul@n1bug.com> wrote:

I am trying to determine whether the VFO/SigGen would be a
worthwhile upgrade to several crystal oscillators and one inferior
TCXO in my station. I have a few questions.

Has anyone measured accuracy or short and long term frequency
stability? The operating manual says it updates the 27 MHz reference
frequency in .01 Hz steps but doesn't explicitly state how often
(every second?). App Note 006 says the accuracy is 0.1 PPM which is
worse than I would expect if the reference is updated in such small
steps. Maybe we are talking about two different things... accuracy
vs stability/drift?

Am I correct in assuming any error of the 27 MHz reference is
divided down if the output frequency is lower? Eg. if the 27 MHz
reference changes by 1 Hz, an output signal at 2.7 MHz would change
by 0.1 Hz?

Is there any issue with setting the output to 27 000 000?

73,
Paul N1BUG


Re: Side cutters #tool

David Wilcox
 

I bought my XYL a professional grade set of side cutters for her artificial flower decorating hobby....... too much invested after 45 years, and the decorations around the house look great. Got back into the radio hobby and took on a wife at the same time so she was forewarned. Only restriction is NO TOWER IN MY YARD! But, lots of wires in the air. The birds hate me.

David J. Wilcox K8WPE’s iPad

On Dec 13, 2018, at 3:31 PM, juggie@cix.co.uk wrote:

Still using a pair of Lindstrom needle nose pliers that I was given 45 years ago here, still very nice to use too. I’d be using the cutters that I was given at the same time if my xyl hadn’t sniffled them and cut florists wire with them - solved that problem though, divorced her !!

73s all, Nick



Re: Side cutters #tool

Ryan Flowers
 

Another vote for the Hakko. I bought a pair and then my wife thought I didn't, and ordered it for me! So now I have two pair. The second pair is unopened because the first one keeps going and going. I use it for all sorts of things. A great deal! https://amzn.to/2PTft3T

--
Ryan Flowers - W7RLF
MiscDotGeek.com
Multi Band BITX40 using QRP Labs Filters
The BITX40 FAQ


Re: QSX tcvr built-in Spectrum Analyzer

Qi Fan
 

Now I can't imagine how long will the wait time be for the second batch of orders.


Re: Side cutters #tool

turnsouth@...
 

Wow, thanks for all the advice, so many choices.

After reading the cautions, I wonder if it is the leads from transistors that play havoc on cutters. After a series of LED Christmas tress I built in a row this year for the XYL, I noticed they seem to be a hard steel compared to resistors and the rest.


Pictures in operation [was Re: [QRPLabs] Side cutters] #pics

KB3USG
 

On 2018-12-13 18:58-0000, m5fra2 via Groups.Io wrote:
See http://www.m5fra.org.uk/home-construction/qcx-transceiver-build/
So, I'm having issues with mine (and I'm a bit of a newbie) and one of
the things I wondered about was my decoder detecting I's, E's, H's and I
didn't know whether this was normal.

Looks as if it _is_ normal.

Thanks for publishing the picutures!

Paul
KB3USG


QCX Antenna Analyser feasibility #firmware #qcx

Pedro Henrique Kopper
 

Hello,
I was wondering how feasible it would be to implement a crude antenna analyzer in the QCX transceiver. It already has a SI5351 onboard and an exposed RF input, so it should be mostly a matter of implementing sweep functionality to the signal generator and attaching the transceiver to a resistive bridge, feeding it's output back to the RF input port.

Thanks,
Pedro


Re: Side cutters #tool

Les G3VYZ
 

I also have G8ARF :-)

I have two pairs of side cutters from RS (548-164) which have an attachment that stops the
wire offcut from flying across the room. They are over forty years old, still going strong and
are still sold by RS.


Re: #wspr U3S for 2m WSPR: How to remove the frequency-swing at start of transmission #wspr

M0RON
 

Thanks for that Hans, 
My other two u3s both have park set to 2 and 15000000 so I just set this one the same when doing initial set up.
If I set to park mode 3 this turns park mode off between transmissions if I read it correctly. I'll try it and see. I have two u3s with the OCXO kit fitted so if it works I'll switch it off on both OCXO kits.
Andy
--
The universe is made up of Protons, Neutrons, Electrons but contains only one M0RON.


Re: Shack clock contrast adjustment

KI7MWA
 

....And NOW...like Ken, I am answering my own question: having MISread the construction manual, I supposed that "no connection" was one of the intended options when, in fact, THE ONLY TWO OPTIONS specified by the manual are jumper and 220k.  It is right there on page 6..."Install one of the two choices:"


Re: Side cutters #tool

juggie@...
 

Still using a pair of Lindstrom needle nose pliers that I was given 45 years ago here, still very nice to use too. I’d be using the cutters that I was given at the same time if my xyl hadn’t sniffled them and cut florists wire with them - solved that problem though, divorced her !!

73s all, Nick


Re: Side cutters #tool

m5fra2@...
 

I also have G8FRA!

 

From: QRPLabs@groups.io <QRPLabs@groups.io> On Behalf Of Frank W1FRA
Sent: 13 December 2018 19:50
To: QRPLabs@groups.io
Subject: Re: [QRPLabs] Side cutters #tool

 

Nice callsign !  M5FRA !

 

Frank  W1FRA

 

On Thu, Dec 13, 2018 at 2:09 PM Mike W <mike@...> wrote:

Toffee hammer and 1/8" wood chisel, best cut ever. Bit of a pain grinding the
nicks out of the blade though <vbg>

On 13 Dec 2018 at 15:46, Pedro Henrique Kopper wrote:

> I've been using nail trimmers for a long time and they work great





Re: Shack clock contrast adjustment

KI7MWA
 

Sorry, wrong numerator...should be maximum 1.56 volts.


Re: Shack clock contrast adjustment

KI7MWA
 

If I am reading the schematic correctly, the three options (no connection/jumper/resistor) produce three different results:  with no connection (meaning neither R4 nor a jumper is installed), the contrast control pot is connected to ground, therefore Vcon is connected to ground (through more or less resistance), and the pot does nothing at all; with the jumper, the contrast control pot provides a variable voltage to the Vcon pin between 0 and +5 volts; with a resistor installed, the contrast control pot is one element of a voltage divider, therefore providing Vcon a voltage of between 0 and a maximum determined by the ratio of the maximum resistance of the pot to the sum of that resistance plus the resistance of R4 - in the case of R4= 220k, the maximum would be 5V * (100/(100+220)) = 3.44 volts.

In my experience, with no connection, the LCD demonstrates two states: no contrast (with the contrast control pot fully clockwise I can see characters in the blocks of dots if I look at the LCD from the side, but not if I am looking straight on), and blank (with even a slight shift of the pot, neither characters nor blocks of dots are visible).  


Re: Side cutters #tool

 

Nice callsign !  M5FRA !

Frank  W1FRA

On Thu, Dec 13, 2018 at 2:09 PM Mike W <mike@...> wrote:
Toffee hammer and 1/8" wood chisel, best cut ever. Bit of a pain grinding the
nicks out of the blade though <vbg>

On 13 Dec 2018 at 15:46, Pedro Henrique Kopper wrote:

> I've been using nail trimmers for a long time and they work great.






Re: #qcx #problem Radio newbie and QCX large audio hum... #qcx #problem

N3MNT
 

Since you said that you used a little too much heat on the audio pot, it is possible that you overheated the cap C1 as that is more delicate than the large pot.


Re: #qcx #problem Radio newbie and QCX large audio hum... #qcx #problem

Dave Redfearn
 

Paul,
When you are describing "peaking the BPF", do you mean the receiver alignment where you adjust C1, R27, R17, & R24 or are you troubleshooting low transmit output power by adding/removing turns from the low pass filter coils?

For the receiver alignment where you adjust C1, R27, R17, & R24 (8. Alignment Menu), you need to follow the instructions in the manual and not have anything connected to antenna jack.

From the Rev 3 manual: 
"In summary: the alignment tools built into the radio consist of a signal generator which injects a signal into the RF front end, and digital signal processing which adds a 250-Hz digital filter to the existing 200Hz analogue filter, and calculates the amplitude of the signal detected in that bandwidth. During alignment, the amplitude is displayed on-screen as an intuitive bar across the bottom row of the display. Using a screwdriver, you adjust the trimmer component in order to maximise or minimise the displayed amplitude.
Unplug the antenna during alignment of the radio!"

Also, since the QCX has no built-in protection for the finals, you do not want to transmit into the Loop antenna unless it has been resonated on the frequency you are using (or any other antenna for that matter).
A safe way to do this would be to use a resistive VSWR bridge in-line which can provide a 50 ohm load to the transmitter while the antenna is being tuned.
Here is an example of a resistive SWR bridge kit: https://www.qrpkits.com/swrind_case.html and an example of this type of circuit included in an antenna tuner: https://qrpguys.com/multi-tuner

73 - Dave, N4ELM