Date   

Re: no minimum / zero volume on QCX - resolved

Brien Pepperdine <brianpepperdine@...>
 

Allison wins this round of Jeopardy tonite! tnx I think all is good again.

While it did appear that the ground lug of the pot was at ground potential... I had been trying to be very careful around the soldering and mechanical contacts of the new pot since the old one had been pulled out and I did not want to compromise the solder hole and solder connection if I could avoid it, so I guess the solder connection was just that much not robust enough. I had 'burned out' the pot's wiper previously when inserting a necessary jumper to C22 from the wiper (lost that hole/trace to one leg of C22 when removing old electrolytic - installing new 1 uf cap).

I put some more solder on the connection of the pot ground lug.. which I been trying to avoid in case I had to remove pot or make any other remediations before it seemed OK to put back together. That bit more solder did the job.. maybe the connection was just too tentative - meter readings SEEMED to indicate the lug was OK with respect to ground - but I guess not.

Anyhow, now I have minimum audio and I can turn the strong stations down in volume. I will check it out further tomorrow when 40m returns to service - too late in the evening now.

tnx agn es 73 de

Brian VE3VAW

---------- Original Message ----------
From: ajparent1/KB1GMX <kb1gmx@...>
Date: November 29, 2019 at 7:07 PM

That suggest the ground side of the pot is not actually connected to ground
(soldering) or the pot has an internal open to the grounded end of the
resistive wafer.  IF you measure under 3 ohms from the wiper to ground
end at minimum volume try measuring from the ground lug itself to
board ground as that should lead to your failure.

Its possible when you remove the original you damage the ground
trace or though hole.

Allison
------
Please reply on list so we can share.
Off list email goes to trash, I had to due to scrapers.


 


Re: no minimum / zero volume on QCX

ajparent1/KB1GMX
 

That suggest the ground side of the pot is not actually connected to ground
(soldering) or the pot has an internal open to the grounded end of the
resistive wafer.  IF you measure under 3 ohms from the wiper to ground
end at minimum volume try measuring from the ground lug itself to
board ground as that should lead to your failure.

Its possible when you remove the original you damage the ground
trace or though hole.

Allison
------
Please reply on list so we can share.
Off list email goes to trash, I had to due to scrapers.


no minimum / zero volume on QCX

Brien Pepperdine <brianpepperdine@...>
 

I had to replace the volume pot on my QCX due to damage when trying to remedy issues after replacing C21 and C22 electrolytic 10uf caps with 1 uf caps.

The new 5K pot does NOT provide a minimum/zero volume. Max seems fine but some signals need a further reduction in volume and even with the pot turned to low setting (CCW) there is still too much volume. Certainly not zero (which it should be, right?)

I get about 3 ohms at low point and 5K to high point from both sides of wiper (so signal input and at ground to wiper) each side of the pot.

I am leaving it for now... other things to do for now rather than ruminate or poke, but I thought I would ask The Collective.

tnx

Brian VE3VAW


Re: QCX 20 off frequency

George Korper
 

I have reset to defaults. Is this an alignment issue? The problem is on transmit. 


On Fri, Nov 29, 2019, 3:00 PM Chopper <bob@...> wrote:
Check out the freq adjustment section of the manual on page 100.  That is where you would adjust it.


Re: QCX 20 off frequency

N3MNT
 

Check out the freq adjustment section of the manual on page 100.  That is where you would adjust it.


QCX 20 off frequency

George Korper
 

Hi All,
I just assembled a second QCX 20. The first unit is working well and made contacts,etc.
The second unit transmits 2 KHZ up the band  and likewise receives 2 KHZ
down the band. I have checked for solder joints, etc. and the receiver works but
the second stage of alignment is not working well. This unit has the 1.01 firmware.
Need help before I troubleshoot without narrowing this down.
Thanks,
George


Re: #qcx40 #problem no audio #qcx40 #problem

James Daldry W4JED
 

Hi, John

Section 6 of the manual deals with trouble-shooting. Starts at page 126 in the original manual. One thing to check, before getting too deep, is the resistance from the volume control wiper to each end of the control, on the foil side. Some of the volume control pins were barely long enough to connect to the board, and could disconnect with handling. Make sure that the center connection will sweep to zero ohms with both ends of the control. If that isn't the problem, then go around each of the "little square chips" and measure the voltages with the built-in meter. Report back with any voltages that are more than 20% off the voltages in the troubleshooting chart.

Good luck.

73

Jim W4JED

On 11/29/19 2:02 PM, john.rogers via Groups.Io wrote:

QCX Enthusiasts,
My QCX 40m suddenly stopped producing audio...
Front panel display is OK.
There is no sound from the antenna.
There is no side tone.
Keying the paddle produces clicks--one click for each dit or dah.
Headphones check out fine.

What could have gone wrong?
Where should I start troubleshooting?
It was working fine.
Regards,
John
AC2SG


Re: CW or CW-R

James Daldry W4JED
 

Hi, Guys

Since, unlike with single sideband, you are throwing out a single carrier rather than a sideband, you can use whatever you're comfortable with. As long as your sidetone is the same pitch as the signal you are listening to, your signal will be where the other guy's is. I'm most comfortable with CW-R, since it results in a received pitch that rises with clockwise rotation of the tuning control. Whichever you choose, the carrier frequency will be what the display says, as long as you are listening at 750 hz. That's the frequency of the sidetone. Tap the key, match the pitch, you're right on top of the signal.

73

Jim W4JED

On 11/29/19 3:19 PM, Gary Bernard via Groups.Io wrote:
CW for all bands


-----Original Message-----
From: Mike via Groups.Io <mikeymustang2000@...>
To: QRPLabs <QRPLabs@groups.io>
Sent: Fri, Nov 29, 2019 1:14 pm
Subject: [QRPLabs] CW or CW-R

Group,
On 40 meters...what is the appropriate  choice CW-R or CW?
Thank you!
73's
Mike WA3O 


Re: CW or CW-R

Gary Bernard
 

CW for all bands


-----Original Message-----
From: Mike via Groups.Io <mikeymustang2000@...>
To: QRPLabs <QRPLabs@groups.io>
Sent: Fri, Nov 29, 2019 1:14 pm
Subject: [QRPLabs] CW or CW-R

Group,
On 40 meters...what is the appropriate  choice CW-R or CW?
Thank you!
73's
Mike WA3O 


CW or CW-R

Mike
 

Group,
On 40 meters...what is the appropriate  choice CW-R or CW?
Thank you!
73's
Mike WA3O 


Re: Saving battery current #mods #qcx #supply

Ronan Cantwell
 

Simply replace the existing 7805 with a Recom r-785.0-0.5.  It's pin compatible and fits neatly where the 7805 was. Then reduce the the backlight supply current by changing R48 to 1.8 k (yep, seems high but it works fine). I've done this to both my QCX kits. Current draw on receive is now  a VERY respectable 73 mA.

Cheers, 
Ronan MM0IVR


Re: #qcx40 #problem no audio #qcx40 #problem

N3MNT
 

Did you update to the latest firmware 1.02?  If so what is your side tone set at ( Menu 4.8) Try 750.


#qcx40 #problem no audio #qcx40 #problem

john.rogers@...
 

QCX Enthusiasts,
My QCX 40m suddenly stopped producing audio...
Front panel display is OK.
There is no sound from the antenna.
There is no side tone.
Keying the paddle produces clicks--one click for each dit or dah.
Headphones check out fine.

What could have gone wrong?
Where should I start troubleshooting?
It was working fine.
Regards,
John
AC2SG


Re: QCX firmware update- row of boxes when programmer connected

Alan G4ZFQ
 

On 29/11/2019 17:53, Hannu OH1HAQ wrote:
Thanks for the reply! So you recon it's safe to power up the programmer?
You have cut off the QCX 5 volt pin.
But have you got the programmer cable connected correctly? The 5 volts from the programmer should go to the missing pin.

73 Alan G4ZFQ


Re: QCX firmware update- row of boxes when programmer connected

Hannu OH1HAQ
 

With sweaty palms I tried it, and the update worked great!


Re: QCX firmware update- row of boxes when programmer connected

Hannu OH1HAQ
 

Thanks for the reply! So you recon it's safe to power up the programmer?


Re: QCX firmware update- row of boxes when programmer connected

Richard G4TGJ
 

The programmer is probably holding the processor in reset and so it never clears the screen.
--
73
Richard
G4TGJ


QCX firmware update- row of boxes when programmer connected

Hannu OH1HAQ
 

hI!

Trying to update the firmware with chinese USBAsp. (https://www.ebay.com/itm/Wire-AVR-Programmer-USBasp-USB-ISP-ATMEGA8-Support-Win7-64Bit-5V-ATMEGA128-6PIN/232327462892?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2648

I clipped the 5V pin off from the QCX just to be sure. ( bottom left corner when looking from the front) I the checked that the programmers gnd pin is on bottom left corner of the connector when the key of the connector is up.

Connected the the programmer but did not yet plug it in to pc.
I'm getting one row of boxes on the qcx display. Disconnecting the cable from the programmer put things back to normal. 

What gives?


Re: Multiband QCX

John VA7JBE
 

There are a few people who've tried to multband the QCX before, and it seems to be pretty easy.  In regards to the receive chain, T1 and the bandpass filter are the crux.  Some people have gotten around it by switching in more capacitance as needed to change the BPF peak (my favorite example of this is a varactor diode with a trimpot to really dial it in.)  Others have replaced the iron powder core with ferrite and a simple trifilar winding to maintain the balanced input but eliminate the BPF.  Still others have unbalanced the input entirely (like Guido PE1NNZ did: https://groups.io/g/QRPLabs/message/38064).  I seem to recall somebody else adding a socket to T1 so they could plug in different modules, but I'm afraid I can't find a reference.  Most approaches seem to work reasonably well and nobody has reported a significant degradation of performance so far.

Good luck!
John VA7JBE


Re: More paddles and keys ...

Mike Easterbrook
 

Thanks Martin 
Next time I'm in the area I'll take a look if still in need.  Found almost matching item today in Handyman Centre (Lucky Plaza) but very tight fit on the M3. It'll be a struggle but may work
Mike 9V1LX 

On Fri, 29 Nov 2019, 14:06 Martin Rath, <martin.rath@...> wrote:
Hi,

Marina Square mall and i12 Katong mall both have music instrument shops. Should be pretty easy to find.

73’s 9V1RM 

On Fri, 29 Nov 2019 at 11:19, Mike Easterbrook <mike.easterbrook.2012@...> wrote:
Hi Eric
Thanks for the tips.  Never thought of taking the DIY to the next level - shame on me! 
Now I need to find a local source of piano wire (in 9V/9M) 
Thanks again Mike 

On Fri, 29 Nov 2019, 05:18 Eric KE6US, <eric.csuf@...> wrote:

They aren't difficult to wind. K&S Metals has small dia. piano wire. Use an ordinary screw as a form. I usually go with a screw the next size down from what I want as they tend to unwind a little. You can also wind them on dowels and bamboo skewers. I do this often when I need one right away for development, then replace it later when I have time as the commercial ones have much nicer finish winds on the ends.

Eric KE6US


On 11/27/2019 6:36 PM, Mike Easterbrook wrote:
Thanks for the suggestion Niels. That was one source of springs I hadn't thought of. Those that I've checked so far are either wrong ID for the 3mm screw or wound in wrong "sense" .

Continuing to look. Closest I've found is tensioning wire for net curtains but all I can get here are too small ID
Mike

On Mon, 25 Nov 2019, 19:34 Niels Jalling, <niels@...> wrote:
Take a look inside a ballpen from your pile of old pens.
73 de
OZ9NY Niels