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Re: Pin Confusion #u3s

N3MNT
 


This does the same thing with easier jumpers to install.


On Sat, Feb 6, 2021 at 01:11 PM, Mont Pierce KM6WT wrote:
On Sat, Feb 6, 2021 at 06:41 AM, KI7MWA wrote:
the synth board makes a connection between the +5V pin and the Heat pin...
Since the Synth board already connects the Heat track to +5V, you could also do the following:

Jumper all 3 as circled in Red below.  Thread a wire down one hole, up the next, and down again in the last hole.
Then you can apply +5V to any of the 3 pins circled in Blue.  Or even use one of those pins to power something else.



73
km6wt


Re: How do I restart the alignment process on a QCXmini?

Jim AJ8S
 

When you reset the QCX all settings are lost. I keep a text file listing the values I use for all 3 QCXs. That makes it easier to re-enter everything after doing the reset and alignment.


Re: Pin Confusion #u3s

Mont Pierce KM6WT
 

On Sat, Feb 6, 2021 at 10:11 AM, Mont Pierce KM6WT wrote:
Then you can apply +5V to any of the 3 pins circled in Blue.
Oopss... I meant "Yellow"

(should have proof read)


Re: Pin Confusion #u3s

Mont Pierce KM6WT
 

On Sat, Feb 6, 2021 at 06:41 AM, KI7MWA wrote:
the synth board makes a connection between the +5V pin and the Heat pin...
Since the Synth board already connects the Heat track to +5V, you could also do the following:

Jumper all 3 as circled in Red below.  Thread a wire down one hole, up the next, and down again in the last hole.
Then you can apply +5V to any of the 3 pins circled in Blue.  Or even use one of those pins to power something else.



73
km6wt


Re: Pin Confusion #u3s

Mont Pierce KM6WT
 

On Sat, Feb 6, 2021 at 09:19 AM, KI7MWA wrote:
if one is not using the TXCO, and one is using a 5V power supply, one could connect one's power supply to the +5V and Gnd pins, so long as one has the jumper installed for the connection between the +5V and PA pins.  Right?
Yes, correct.


73
Mont - km6wt


Re: Pin Confusion #u3s

KI7MWA
 

KM6WT:

Okay, thanks.  The purpose of the +5V-Heat pin jumper is to provide for the greater current flow needed by the TXCO oven.

And, by the same token, if one is not using the TXCO, and one is using a 5V power supply, one could connect one's power supply to the +5V and Gnd pins, so long as one has the jumper installed for the connection between the +5V and PA pins.  Right?


Re: Mini 40 Display Issue Restart

Steven Dick
 

"1.  Both mini 20 and mini 40 IC2s work in mini 20 but no backlight. "  Assuming menus in both units are set correctly for enabling backlight, if I understand this statement,  there is a problem with mini 40's IC2 relating to the LCD circuitry if IC2 from the mini 20 works WITH backlight in the mini 20, and IC2 from the mini 40 works but WITHOUT backlight in the mini 20. So IC2 is likely damaged or has a hairpin piece of wire shorting pin 14 to an adjacent pin (unlikely).  Pin 14,  does double duty.  It is used for communication with the LCD during LCD updates and it is used to control turning on Q100, the display switch  Some of the symptoms indicate no communication to the LCD which will occur if pin 14 of IC2 not working properly. Check soldering around pin 14 of the LCD on the mini 40 display module - make sure there are no shorts to adjacent pins such as short between pin 14 to 15 or 14 to 13.   If there is a short, it may have damaged IC2 by applying 12 volts to it through the 560 ohm current setting resistor when the LCD's LED is not activated by Q100.

-Steve K1RF

------ Original Message ------
From: "hamhog1" <gwgrogg@...>
Sent: 2/6/2021 10:19:19 AM
Subject: [QRPLabs] Mini 40 Display Issue Restart

I decided to restart from the beginning in troubleshooting my Mini 40.  All I have is the top row of blocks.
Using the Troubleshooting guide, I did the following:
1.  Adjusted R36.
2.  Made sure IC2 was inserted correctly.
3.  Check to be sure no bent pins.  All were seated correctly.
4.  I heard the 20 mhz crystal at 20.005 mhz on shack receiver.  Also saw on scope.
Next I swapped the display board, IC2, and controllers with my Mini 20 which works well.  What I observed:
1.  Both mini 20 and mini 40 IC2s work in mini 20 but no backlight.  Neither IC2s seem to work in mini 40 but with backlight and top row. of blocks.
2.  Both display boards work in mini 20 but no backlight.  Both display boards show top row of blocks in mini 40 with backlight.
3.  Both controller boards work in mini 20 but no backlight.  Both controller boards show top row of blocks in mini 40 with backlight.
Conclusion:  IC2 in mini 40 appears to be okay.  Display board in mini 40 appears to work okay.  Controller board in mini 40 appears to be okay.
Next I measured voltages with my digital multimeter using the voltage sheet from the manual as a guide.
1.  All readings were nominal down to the reading for left side of C45.  Showed 1.28 v instead of 2.42 v. Also C46 showed .85 v instead of 2.30 v.
2.  I did not check ICs 5-10 at this time.
3.  LCD pin 6 showed .48 v instead of 0 v.
4.  LCD pins 7-11 all showed 4.94 v which is quite high.
5.  LCD pin 14 showed 4.94 v instead of 0 v.
6.  LCD pin 15 showed 3.71 v instead of 4.41 v.
Finally I checked continuity and resistance between LCD and IC2 with IC2 removed.  It showed 0.0 ohms resistance.

Trying not to get frustrated.  It probably is something simple, but where to look?

Thanks for any help.
Gary K4VIG


Virus-free. www.avast.com


Re: #u3s #troubleshooting No Spots / not sure transmitting #u3s #troubleshooting #help #lpf

Brad G
 

This is all GREAT info for me.  Thank you very much!  And thanks for keeping me moving forward with this project.  I really like seeing my U3S work and watching what it can do.  Brad / K0WET


Re: Pin Confusion #u3s

Mont Pierce KM6WT
 

On Sat, Feb 6, 2021 at 05:19 AM, KI7MWA wrote:
Page 15 of the U3S construction manual says: "To run the transmitter using the 5V supply, be sure to connect a wire between the +5V and PA pins. This is shown by the short red horizontal line in the diagram (below)."  But, in the diagram there are actually TWO short red horizontal lines, one between the second and third pins of the 4-pin header next to the capacitor labeled C1, and another between the second and third pins of the 11-pin header at the edge of the board, the pins labeled +5 and Heat.

With no jumpers installed, my DVM shows continuity between the +5 and Heat pins.  Is this correct? Or do I have a short somewhere?

At the bottom of the U3S webpage (click here) there are two diagrams from the PCB layers showing the traces in the board.

In the left image, you can see what pins are already connected, so helps to understand how the jumpers are described in the assembly manual.

The PA track is separate and thicker, to allow applying a higher voltage to the PA only.

The +5V Heater track is thicker to allow more current.


73
km6wt


Re: Ultimate 3S #u3s

Rob Giuliano
 

Interesting.  Thanks for the idea!
I am hoping to put out about 250 mW on 10m, and whatever I get on the lower frequencies will be fine.
Halden brought up the bias changes on hs MOSFET (BSN20-7) and I think I experienced this on the BS170.
  I just want one bias setting.
My experience:
  Set bias for 40m and only transmit on 40m -> no issues
  Same bias for 20m and transmit on 20 and 40m -> no issues
  Add 15m and 10m (4-bands) and the BS170 over heats.
  Set bias for 10m -> no issues
  Same bias (10m) and let run on 4 bands - BS170 over heats.
I did not measure this bias level to see if/how much it changed - maybe next time.

Curious if you have noticed a bias voltage changes on those HF bands.  Or if the higher PA voltage makes it easier on the MOSFET?
Just using WSPR for now.  I may investigate other modes later.

Thanks again!
Rob KB8RCO


Re: Ultimate 3S #u3s

Rob Giuliano
 

Thanks Halden - Appreciate the infomration!
I will look into the BSN20-7MOSFET.  I am hoping to put out about 250 mW on 10m, and whatever I get on the lower frequencies will be fine.
I'd be interested in seeing your "PCB adaptor".  Does it allow for the case as part of the heat sink?
Also curious if the bias voltage changes on the lower (HF) bands.  It seems to do that (somewhat) on the BS170.

Thanks again!
Rob KB8RCO


Re: Qgl1 gps question

Roger Hill
 

Hi Art.
That does not sound good. But you might want to inspect the area around pin 2 of IC2 to pin 23 of the RF module for solder blobs, whiskers etc. Maybe even under the RF module.


If nothing found, I agree that a new RF module sounds like it is necessary.

Roger
8P6RX

On 6 Feb 2021, at 11:09, Roger Hill <rhill@...> wrote:

Hi Art.


So it sounds as though you have a faulty IC2 (unlikely), or a short to ground on the output side (pin 2).


You can check the short by removing power from the unit, and with your meter on 'Ohms', check from pin2 to ground...it should be a very high value. A low value will cause the symptoms you are seeing.


Possibly C4 is in backwards.

Roger

8P6RX

---
***************************
Roger Hill
***************************


On 2021-02-06 10:51, Art Olson wrote:

Eike

Think I have located the problem - no 3.3v on the pin 2 of IC2. When powered up IC2 run hot to the touch.  There is 5.1 v on pin 3 (vin). Verified R7 and R6 are correct values. I have looked for a pinout diagram for the Rf module but could not locate one so don't know the pin numbering on the module. But would seem without any 3.3v from IC2 it wont work. there is 3.3v when powered off on, I assume pin 22 of the RF module

Art
N2AJO


Re: Qgl1 gps question

Art Olson
 

Roger

Yes pin 2 is shorted to ground. Removed IC2 and checked pin 2 - still shorted. Removed C4, C5, C2 and R7 - still shorted to ground. Only connection left is to pin 23 of Rf module which seems it is shorted to ground also. Maybe time for a now gps module


Re: Pin Confusion #u3s

KI7MWA
 

N3MNT:

Okay, but on page 3 of the synth assembly manual, the PCB tracks diagram shows that pins 8, 9, and 10 are connected together...and my DVM agrees.  Pin 8 is not independent.


Re: Pin Confusion #u3s

KI7MWA
 

Another question:  The diagram on page 15 shows +5V supply voltage applied to the PA pin, with the (upper) jumper connecting the PA pin to the +5V pin.  But, with the (upper) jumper installed, the +5V supply could just as well be connected to the +5V pin on the board, because with the (upper) jumper installed the +5V pin is in common with the PA pin. 

You could argue that the +5V supply HAS to be connected to the PA pin if one wants to install the (lower) jumper between the +5V pin and the Heat pin when you want to supply voltage to the oven of the TXCO (should you be using it). 

But if the synth board itself makes a connection between the +5V pin and the Heat pin (my DVM shows 0 ohms resistance between the +5V pin and the Heat pin when the synth board is in place), why would you need the (lower) jumper?


Mini 40 Display Issue Restart

hamhog1
 

I decided to restart from the beginning in troubleshooting my Mini 40.  All I have is the top row of blocks.
Using the Troubleshooting guide, I did the following:
1.  Adjusted R36.
2.  Made sure IC2 was inserted correctly.
3.  Check to be sure no bent pins.  All were seated correctly.
4.  I heard the 20 mhz crystal at 20.005 mhz on shack receiver.  Also saw on scope.
Next I swapped the display board, IC2, and controllers with my Mini 20 which works well.  What I observed:
1.  Both mini 20 and mini 40 IC2s work in mini 20 but no backlight.  Neither IC2s seem to work in mini 40 but with backlight and top row. of blocks.
2.  Both display boards work in mini 20 but no backlight.  Both display boards show top row of blocks in mini 40 with backlight.
3.  Both controller boards work in mini 20 but no backlight.  Both controller boards show top row of blocks in mini 40 with backlight.
Conclusion:  IC2 in mini 40 appears to be okay.  Display board in mini 40 appears to work okay.  Controller board in mini 40 appears to be okay.
Next I measured voltages with my digital multimeter using the voltage sheet from the manual as a guide.
1.  All readings were nominal down to the reading for left side of C45.  Showed 1.28 v instead of 2.42 v. Also C46 showed .85 v instead of 2.30 v.
2.  I did not check ICs 5-10 at this time.
3.  LCD pin 6 showed .48 v instead of 0 v.
4.  LCD pins 7-11 all showed 4.94 v which is quite high.
5.  LCD pin 14 showed 4.94 v instead of 0 v.
6.  LCD pin 15 showed 3.71 v instead of 4.41 v.
Finally I checked continuity and resistance between LCD and IC2 with IC2 removed.  It showed 0.0 ohms resistance.

Trying not to get frustrated.  It probably is something simple, but where to look?

Thanks for any help.
Gary K4VIG


Re: Qgl1 gps question

Roger Hill
 

Hi Art.


So it sounds as though you have a faulty IC2 (unlikely), or a short to ground on the output side (pin 2).


You can check the short by removing power from the unit, and with your meter on 'Ohms', check from pin2 to ground...it should be a very high value. A low value will cause the symptoms you are seeing.


Possibly C4 is in backwards.

Roger

8P6RX

---
***************************
Roger Hill
***************************


On 2021-02-06 10:51, Art Olson wrote:

Eike

Think I have located the problem - no 3.3v on the pin 2 of IC2. When powered up IC2 run hot to the touch.  There is 5.1 v on pin 3 (vin). Verified R7 and R6 are correct values. I have looked for a pinout diagram for the Rf module but could not locate one so don't know the pin numbering on the module. But would seem without any 3.3v from IC2 it wont work. there is 3.3v when powered off on, I assume pin 22 of the RF module

Art
N2AJO


Re: Pin Confusion #u3s

N3MNT
 


From Schem.


Re: Qgl1 gps question

Art Olson
 

Eike

Think I have located the problem - no 3.3v on the pin 2 of IC2. When powered up IC2 run hot to the touch.  There is 5.1 v on pin 3 (vin). Verified R7 and R6 are correct values. I have looked for a pinout diagram for the Rf module but could not locate one so don't know the pin numbering on the module. But would seem without any 3.3v from IC2 it wont work. there is 3.3v when powered off on, I assume pin 22 of the RF module

Art
N2AJO


Re: Pin Confusion #u3s

KI7MWA
 

N3MNT: "The lower jumper connects 5V to the heater if using the TCXO."

So, in the case where one is NOT using the TXCO, the synth board makes a connection between the +5V pin and the Heat pin...just for the hell of it?

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