Date   
Re: DDS VFO - No Heartbeat

Alan G4ZFQ
 

The PPS led is flashing and I enabled the GPS setting on the VFO settings.  But I do not
have the heartbeat symbol.
Michael,

I do not remember seeing it.
But do you have to set the display? As on Line1 of the operation document.

73 Alan G4ZFQ

Re: Low RF power output -- would this fix the problem?

Hans Summers
 

Yes, plated through-hole. I find it convenient to solder to the top, sometimes, without cleaning out the hole.

73 Hans G0UPL 

On Dec 1, 2017 5:52 PM, "Alan G4ZFQ" <alan4alan@...> wrote:

I don't actually have one of these devices, but is it feasible to put
in the likes of stiff "Vero Pins" in the holes for the coil wirres to
be soldered to, so you aren't soldering direct to tracks that may lift
if you fiddle with them too much?

Chris,

I do not have one either. But you are not just soldering to a track. The coil mounting points will have a plated-through hole (Maybe Hans can confirm) which is quite robust. The only time I have damaged one of those was when I attempted to clean out the hole to refit something "properly".
A pre-tinned wire will only need a quick dab of the iron to make a good joint.
However if you can find something that is a tight fit then that would not be a bad idea.

73 Alan G4zFQ


Note Hans' post here.  https://groups.io/g/QRPLabs/message/17970
It is not necessary to get the wire through the hole, just solder to the
top.



Re: Low RF power output -- would this fix the problem?

Alan G4ZFQ
 

I don't actually have one of these devices, but is it feasible to put
in the likes of stiff "Vero Pins" in the holes for the coil wirres to
be soldered to, so you aren't soldering direct to tracks that may lift
if you fiddle with them too much?
Chris,

I do not have one either. But you are not just soldering to a track. The coil mounting points will have a plated-through hole (Maybe Hans can confirm) which is quite robust. The only time I have damaged one of those was when I attempted to clean out the hole to refit something "properly".
A pre-tinned wire will only need a quick dab of the iron to make a good joint.
However if you can find something that is a tight fit then that would not be a bad idea.

73 Alan G4zFQ


Note Hans' post here. https://groups.io/g/QRPLabs/message/17970
It is not necessary to get the wire through the hole, just solder to the
top.

Re: One more comment on QCX toroids - number of turns

w7aqk
 

Hans and All,

 

Well, my 40 meter QCX is only putting out a little over 2 watts using the turn count from the manual.  Shouldn’t it be closer to 4 watts?  That measurement was made using a dummy load and an Elecraft W1 power meter.

 

Dave W7AQK

 

 

 

From: Hans Summers
Sent: Friday, December 1, 2017 6:56 AM
To: QRPLabs@groups.io
Subject: Re: [QRPLabs] One more comment on QCX toroids - number of turns

 

Hi Steven

 

Thanks for the info. I am not ignoring it. But I need to find some time to look through all the documentation and try to find out why the differences. Interestingly there aren't ever complaints about low power on 40m... even if the inductor turns are too many! 

 

Let me get back to you on this one when I have had a chance to look at the docs. 

 

73 Hans G0UPL

 

 

DDS VFO - No Heartbeat

Michael Monteith
 

I purchased a DDS VFO kit along with the QLG1 GPS.  The firmware on the VFO is 1.01a. 
The PPS led is flashing and I enabled the GPS setting on the VFO settings.  But I do not
have the heartbeat symbol.   Do I need a firmware update or something else I'm missing?

Thanks
73, Michael
KM4OLT

Re: schottky diode now another question!

Willi, OE1WKL
 

Grinder is the result of an unfortunate translation from German. In German the term "Schleifer" is sometimes used for the center pin of a potentiometer, which should be translated as "slider" in this context, because this element "slides" along the resistors surface. But "schleifen" can also mean "to grind" ("eine Axt schleifen = to grind an axe), and as a result the "Schleifer" became a grinder.... ;-)
Vy 73
WIlli, OE1WKL

Re: Low RF power output -- would this fix the problem?

Chris Wilson
 

Hello Alan,


I don't actually have one of these devices, but is it feasible to put
in the likes of stiff "Vero Pins" in the holes for the coil wirres to
be soldered to, so you aren't soldering direct to tracks that may lift
if you fiddle with them too much? They might allow easy removal of the
transformer for changes or fault finding with an increased margin of
safety for the PCB?

Friday, December 1, 2017

Removing the LPF toroids is difficult.
Bob,
Note Hans' post here. https://groups.io/g/QRPLabs/message/17970
It is not necessary to get the wire through the hole, just solder to the
top.
"I do it all the time"
73 Alan G4zFQ
--

2E0ILY
Best regards,
Chris mailto:chris@...
--
Best regards, Chris Wilson (2E0ILY)

Re: schottky diode

Al Holt
 

BTW, this situation is a good reminder for me. I'm taking the Extra Class exam this weekend and I've found it's always important to read the WHOLE question before jumping at an answer. :-) It's also important to read the whole answer on this type of multiple choice test.  The saying goes, "Put mind in gear before opening mouth," and certainly social media proves that day in and day out!

Re: One more comment on QCX toroids - number of turns

Hans Summers
 

Hi Steven

Thanks for the info. I am not ignoring it. But I need to find some time to look through all the documentation and try to find out why the differences. Interestingly there aren't ever complaints about low power on 40m... even if the inductor turns are too many! 

Let me get back to you on this one when I have had a chance to look at the docs. 

73 Hans G0UPL

On Fri, Dec 1, 2017 at 5:24 AM, Steven Dick <sbdick@...> wrote:
Nope. The original article referred to mix 6 (yellow) for 40 meters.  I used a calculator which also indicated the turns called out in the QCX manual should be correct. However, I tested the L1, L2, and L3 toroids with my LC-200A and got closest with 21 turns for L2 and 19 turns for L1 and L3.  I have confidence with my measurements as I have built many a filter with it, and verified measured results against simulations with a network analyzer.  There are a lot of variables here and it’s best to try to get accurate inductance values using some of the various techniques discussed in other posts before mounting them on the PC board. It’s easy enough to adjust number of turns as needed before mounting them. In my experience in winding many toroids, most inductance values were usually on the high side based on theoretical number of turns, but YMMV
 
-Steve K1RF
 
From: Al Holt
Sent: Thursday, November 30, 2017 8:29 PM
Subject: Re: [QRPLabs] One more comment on QCX toroids - number of turns
 
I have a feeling the original article, which I quickly glanced at, might all be based on Mix 2 (red) toroids. The QCX uses Mix 6 (yellow) for LPFs. And if memory serves me correctly Mix 2's require more turns for a given inductance.

At the time I built my 40m QCX I used the software program mini Ring Core Calculator to double-check the windings count. It's a great program and seems to always agree with QRP Labs' LPF charts. I also found they're within a turn of being the correct value. The LPFs are designed to work on the 2nd, 3rh and above harmonics and aren't going to affect the fundamental frequency very much.

--Al
WD4AH

Virus-free. www.avast.com


Re: schottky diode now another question!

Hans Summers
 

Hi DK

I quoted Peter DL6DSA's comment directly. I have no idea but I assumed "grinder" is a direct translation from German. I found it more convenient to not try to alter any text, just quote it as given. We all know what he means!

73 Hans G0UPL


On Fri, Dec 1, 2017 at 4:09 PM, DK <donaldphilbin@...> wrote:
Hans,

Thank you for your prompt and very informative reply! 

I have another question, this time Peters DL6DSA’s LCD Contrast improvement modification. Peter writes:

"I have found a simple solution for improving the adjustability of the R47 contrast potentiometer in the QCX: By adding additional resistance between the grinder of the R47 and GND, 

The grinder? I don’t think we use this term ( as applied to a potentiometer; a sandwich but not a potentiometer )! 

Is the grinder the “wiper” often the center pin of the potentiometer? I really enjoy learning the differing terms we use for a common hobby. 

I have the 30  M kit which I will build as soon as I return stateside.

Thanks!

D.K. KD6TK 

On Dec 1, 2017, at 19:52, Hans Summers <hans.summers@...> wrote:

Hi Al

That is true, about the main reverse polarity protection diode. However he's not asking about that one, he's asking about the diode in this modification: http://qrp-labs.com/qcx/qcxmods.html#pwrup

73 Hans G0UPL

On Fri, Dec 1, 2017 at 3:48 PM, Al Holt <grovekid2@...> wrote:
It's the lower voltage drop. If a 'regular' silicon diode is used the drop across it is about .6V. The drop across the Schottky is more like .4V. This puts a slightly higher voltage on the PA FETs and a little more power out.



Re: schottky diode now another question!

DK
 

Hans,

Thank you for your prompt and very informative reply! 

I have another question, this time Peters DL6DSA’s LCD Contrast improvement modification. Peter writes:

"I have found a simple solution for improving the adjustability of the R47 contrast potentiometer in the QCX: By adding additional resistance between the grinder of the R47 and GND, 

The grinder? I don’t think we use this term ( as applied to a potentiometer; a sandwich but not a potentiometer )! 

Is the grinder the “wiper” often the center pin of the potentiometer? I really enjoy learning the differing terms we use for a common hobby. 

I have the 30  M kit which I will build as soon as I return stateside.

Thanks!

D.K. KD6TK 

On Dec 1, 2017, at 19:52, Hans Summers <hans.summers@...> wrote:

Hi Al

That is true, about the main reverse polarity protection diode. However he's not asking about that one, he's asking about the diode in this modification: http://qrp-labs.com/qcx/qcxmods.html#pwrup

73 Hans G0UPL

On Fri, Dec 1, 2017 at 3:48 PM, Al Holt <grovekid2@...> wrote:
It's the lower voltage drop. If a 'regular' silicon diode is used the drop across it is about .6V. The drop across the Schottky is more like .4V. This puts a slightly higher voltage on the PA FETs and a little more power out.


Re: output power QCX

MartienPA4H
 

Hi Hans,

Thanks for the explanation. You are correct simulating the whole circuit is a bit difficult as Coss varies during the RF cycle. Therefore I only simulated the low pass section (many topics on that one as well) and found that this one gives about 0.2dB insertionloss and 23 dB returnloss. Perfect! I calculated by hand the resonance of the L4 circuit using the 50 pF as this Coss value seems to be used by other class E experts (like in this link  http: //www.wa0itp.com/classeampdesignrevb.xls    )   Just trying to understand how the circuit works. 

73 Martien PA4H

73 Martien PA4H

Re: output power QCX

Hans Summers
 

Hi Martien 

I just ordered the QCX so it will probably take some time before I can start building and testing. In the meantime I have been looking into the schematics and the links on page 112/113 concerning the class E PA. I also noted that there are quite a few topics about output power in this group as well. According the papers of Paul Harden, the combination of L4/C30 with the Coss of the three BS170's should resonate at the Tx frequency. However if I do the math (Coss is about 50 pF with 3 BS170's in parallel) for 20 meter then the combination of 0,4uH/30pF plus 50pF resonates at 28MHz and not 14 MHz.  Am I missing something?  I also simulated the lowpass filter (I can use expensive software at my work) but this part seems to be perfect.

Coss of the BS170 is I think, a static (DC) measurement in the datasheet. In the practical real-world circuit it is difficult to model (though I am not sure - I am not adept at simulations); since the capacitance also varies during the RF cycle and depends on a lot of other factors; therefore the only thing that works is trial and error. During my development I did exactly this. I just tried many different capacitor values, and plotted the power output and efficiency curves. When I had determined a suitable optimal value, that became the value specified in the kit. The resonance is evidently very broad, therefore there is no need to make the resonance adjustable in the way that the Band Pass Filter is adjustable. 

73 Hans G0UPL

output power QCX

MartienPA4H
 

Hi all,
I just ordered the QCX so it will probably take some time before I can start building and testing. In the meantime I have been looking into the schematics and the links on page 112/113 concerning the class E PA. I also noted that there are quite a few topics about output power in this group as well. According the papers of Paul Harden, the combination of L4/C30 with the Coss of the three BS170's should resonate at the Tx frequency. However if I do the math (Coss is about 50 pF with 3 BS170's in parallel) for 20 meter then the combination of 0,4uH/30pF plus 50pF resonates at 28MHz and not 14 MHz.  Am I missing something?  I also simulated the lowpass filter (I can use expensive software at my work) but this part seems to be perfect.

73, Martien

 

 

Re: schottky diode

Hans Summers
 

Hi Al

That is true, about the main reverse polarity protection diode. However he's not asking about that one, he's asking about the diode in this modification: http://qrp-labs.com/qcx/qcxmods.html#pwrup

73 Hans G0UPL

On Fri, Dec 1, 2017 at 3:48 PM, Al Holt <grovekid2@...> wrote:
It's the lower voltage drop. If a 'regular' silicon diode is used the drop across it is about .6V. The drop across the Schottky is more like .4V. This puts a slightly higher voltage on the PA FETs and a little more power out.


Re: schottky diode

Hans Summers
 

Hi DK

The low voltage drop. The ATmega328 Spec says that the Digital Vcc and Analogue Vcc voltages should not differ by more than 0.3V. Apparently if you violate this, you run the risk of the silicon all locking up. Which is what is happening to some people. It happens because the inductor in series from 5V to the AVcc only has to charge up a small capacitor, which it does very quickly; the main Vcc has to charge up a 470uF which takes fractionally more time, and allows the voltage difference to exceed 0.3V. The diode prevents the two ever being more than 0.3V apart during the start-up. 

Note that all kits now being shipped include an extra Schottky diode which I put in, so that anyone can make this mod if they want. I think a better solution is re-routing the inductor though. No additional components needed. 

73 Hans G0UPL

On Fri, Dec 1, 2017 at 3:35 PM, DK <donaldphilbin@...> wrote:
I have read on the list under modifications for the issue with the display showing blocks upon initial startup and when powered down and immediately having the power applied allows the rig to function normally. I have read and understood the need for the diode; by why a schottky diode? Is the the low voltage drop that does the trick or is it the fast switching speed?

DK Philbin KD6TK



Re: schottky diode

Al Holt
 

It's the lower voltage drop. If a 'regular' silicon diode is used the drop across it is about .6V. The drop across the Schottky is more like .4V. This puts a slightly higher voltage on the PA FETs and a little more power out.

Re: Low audio gain and no power out with 20m QCX

Steve Nichols
 

Sorry, in my last posting I meant Q5, not Q6. That is, if Q5 fails would it mean you get no TX, but can still receive albeit at much lower levels, but the side tone is still normal.

Steve G0KYA

schottky diode

DK
 

I have read on the list under modifications for the issue with the display showing blocks upon initial startup and when powered down and immediately having the power applied allows the rig to function normally. I have read and understood the need for the diode; by why a schottky diode? Is the the low voltage drop that does the trick or is it the fast switching speed?

DK Philbin KD6TK

Re: New QCX on the air

Anatoly G
 

Hi Ron!
Thanks a lot for information concerning your measurements! Your data has nice correlation with modeling data what got by CM2000 for QCX PA. and very useful!

73! Anatoly
UT5ULX



2017-12-01 5:34 GMT+02:00 Ron Jones via Groups.Io <jonesr_99@...>:

Just finished 40 meter QCX build
Great reception!
3.42 watts out with 12 volt power
5.52 watts with 14.8 volts
Measured using Tektronix 465 scope, Output into a dummy load.
37vpp and 47 vpp respectively.
Wound toroids according to instructions, using recommended number of turns.

Ron
W9rcj