Date   
[QCX40] And the beat goes on.....

Jess Gypin <ontarget1911@...>
 

Ok, I'm just not as sharp or something as I used to beūüėõ
Got this out together a bit ago. Turned it on, no smoke. Q1 got really hot in about 3 seconds. No display. Pulled Q3, got good input to look at Q6 and so on to see what was turning on the PA. Q6 was shorted. Changed that and all 3 BS170s in the PA for good measure. I believe the technical term is shotgunning. I can desolder and solder pretty well still. Not too worried about damaging the board.
Turned it on. No smoke, no heat. Tweaked the LCD and boot screen. Walked through the alignment, not a lot of adjustment on some things, not clear how what specifically. Band pass tweaked right to the center of the cap. Receiver worked great. All menu items working, so no logic or display problems. Thought I found it.
Tried transmitting. Got side tone and receiver quieted. No power outlet all. PA finals got really hot fast when key down, like seconds. So, sort of the same as the original problem. Been all over the board. Verified values, no bad solder joints or toroid wire problems found. A couple of stray solder things that might have been an issue, but not obvious. Cleaned a couple of things, touched up all joints, fixed iffy looking or stray solder things. No obvious bridges or issues. Checked all toroids for continuity and clean, well made connections. Looked at T1. The only thing I have not chased down is the middle 5 wrap secondary is showing a no ohm relationship with the primary. "Shorted to" but have not examined the schematic close enough to know if that is normal path between them through the circuit somewhere. No continuity between the other two secondaries and the primary.
I can't keep it on any time at all without the PA finals getting hot now again. So transmitting or something put me back to square one I think. I never did transmit the first time on purpose so not sure they are the same cause.
So, I was going to check the nand hate to see if the final is just "on" from a DC perspective, but now cannot power it up without the PA getting hot immediately. So, that is where I am. The board has been over inspected. I might be forest for the trees now. Cannot do any dynamic testing, don't want to cook something else. As far as I know the logic and receiver should be fine. I was going to go down the PA and sig gen path to see if they were stuck "on" as was well advised, but now can't. I could pull Q6 or something, but probably not advisable. Q6 is NOT shorted like the first time, probably not been turned on long enough to blow this time.
My only hunch is that it may be the final and receiver transmit, receive switch stuck, or sig gen and tx lines from the nand gate both active or stuck high, or Q? in the key shaping turned on all the time, or can you tell I pretty much don't have a clue right now??
I am kinda stuck cause I can't leave it on to troubleshoot. But I will keep looking. It is obvious that if the receiver works/worked, and I got through the alignment, transmitting causes the problem and it just stays that way.
Thoughts?? I am putting it down for now. Don't want to get frustrated beyond the enjoyment factor. Too nice a radio for that, and the receiver and other toys are too cool!

Jess AE0CW

And yes I am supposed to know electronicsūüėĶ. And no oscilloscope available. Just a DVM. We are full time RV and no workshop anymore.

Re: QCX transmit power fading

@CurtisM
 

thanks for replies.  running this on a 30 amp power supply, so no voltage droop.  power output is steady, but lower than it used to be.  only Q6 is warm.  tweaking the turns on the toroids is having no effect.  I questioned my WM2 until running my HW8 which is outputting more power than the QCX right now.  Yes same output power result with 2 different sets of BS170 finals.  I don't see anyone else reporting this behavior.

Curt

Re: QCX transmit power fading

Daniel Ekman SA2KNG
 

If it's on a good supply and not depleted batteries as Don suggested, check if any components gets hot after some transmit, besides the Q1-Q3. Perhaps a capacitor in the C25-C32 range ?

Re: QCX transmit power fading

Don Baker
 

Dropping battery voltage.

db
wb9sts



On Dec 27, 2017, at 5:35 PM, wb8yyy via Groups.Io <wb8yyy@...> wrote:

My 40m version seems to be having fading output power, literally going down with time on my 40m version.  I thought the finals were overstressed with my issues learning to use the GPS, as this dropped power from 3 watts to 1.8 watts on my 40m version.  Replacing the three MPS170 transistors gave the same 1.8 watts.  Now power is fading down to 1.2 watts, and the current seems to be dropping as well.  Is there anything in the circuit that could behave this way?  I checked all the connections in the transmit section. 

Curt

QCX transmit power fading

@CurtisM
 

My 40m version seems to be having fading output power, literally going down with time on my 40m version.  I thought the finals were overstressed with my issues learning to use the GPS, as this dropped power from 3 watts to 1.8 watts on my 40m version.  Replacing the three MPS170 transistors gave the same 1.8 watts.  Now power is fading down to 1.2 watts, and the current seems to be dropping as well.  Is there anything in the circuit that could behave this way?  I checked all the connections in the transmit section. 

Curt

Re: Battery Voltage Meter #qcx

William Martin
 

Kent,

Did you jumper pin 1 to pin 3 (B+ to DVM) ?  See page 101 and 121 (where the pins are).  You need to do this to allow the internal DVM read the battery voltage.  Turning on the battery icon does just that.   You need to jumper the pins.

Bill N7EU

Re: Battery Voltage Meter #qcx

Kent Vanderploeg
 

Thank you!  I just re-read the manual again and was coming back to post my error.  Read The Fine Manual!  

73,
Kent
W9WB

Re: Battery Voltage Meter #qcx

Daniel Ekman SA2KNG
 

You also need to jumper the tree pin connector close to the DC input, pin 1 to 3 (dvm input to +v).

Battery Voltage Meter #qcx

Kent Vanderploeg
 

I enabled the battery meter (Menu 7.2) and connected the QCX to a fully charged (13.1V) 18Ah battery.  The meter is there, but it's showing empty.  I modified Menu 7.3 from 13,800 to 12,000 to see if that would make a difference.  It did not.  Any ideas on this one?  It's not critical, but it would be nice to have an indication of battery status.  For clarity, I did these steps prior to the power-up fix steps listed below.

When I finished assembly of my 40M QCX. On power up, it only showed the top row, all solid, so I proceeded to do the recommended fix and move L5 to cross over pins 20 & 7.  Well, L5 disintegrated (lead fell out of the body) in the process, so I've ordered some replacements.  

73,
Kent
W9WB

Re: LPF frequency curves #lpf

Daniel Ekman SA2KNG
 

On Wed, Dec 27, 2017 at 10:19 PM, Bob Sutton via Groups.Io <zl1rs@...> wrote:
... but aren't the harmonics from the Si5351a already >10dB down on the fundamental, so the over all spurious emissions after the 40dB suppression of the LPF are already much greater than the 43dB required by your USA regulations?

The output from the synth is squarewave-ish, driving different PA designs in the qrp-labs product line, so not looking the same after amplification. on top of that we have coupling in the pcb, grounding and cables that leaks a bit more of the higher order harmonics past the filters.

That said, who knows what questions/problems may have arised if this optimized filter was the design in the qcx (:
If/when I rebuild my U3S to include the 5W PA, I may try these designs in the LPF modules as they're a lot easier and cheaper to mess with rather than on the qcx. Also ordering the latest design on the relay-switched board.

QCX, what a kit

Kees T
 

Hans, I am very impressed with your QCX CW Transceiver kit. Excellent design from what I can see and an impressive list of functions/capabilities. That's one way of working the kinks out of a new design .....by shipping 2500 of them ;o). 

The only "problem" encountered was the 20K potentiometer vs 50K potentiometer and that was easy enough to fix.

There are some great ideas for an enclosure on your website and I'm leaning towards the one built from PC board material and using an external magnetically attached KX-3 type paddle with the magnets recessed. That way, I also have room for some R/C LiPo batteries.

I have one on 40m and one on 20m.

73 Kees K5BCQ

Re: Firmware update with USBasp

Alan G4ZFQ
 

Is Extreme Burner AVR downloadable through anywhere but fishy third-party sites?  I can't find one so far.
_._,_._,_
The home site http://extremeelectronics.co.in/avr-tutorials/gui-software-for-usbasp-based-usb-avr-programmers/ sends you to a site that asks you to accept emails in return for the program. It's your choice. You do not have to use it.

Have you tried the USBasp on another computer in case there is some incompatibility with the first?

73 Alan G4ZFQ

Re: LPF frequency curves #lpf

Bob ZL1RS
 

Hi Paul

The doc says about the stock 40m LPF ...

"The insertion loss across the band is low and the harmonics are suppressed but not as much as the FCC regulations (Part
97.307 says “(d) For transmitters installed after January 1, 2003, the mean power of any spurious emission from a
station transmitter or external RF power amplifier transmitting on a frequency below 30 MHz must be at least 43 dB
below the mean power of the fundamental emission.‚ÄĚ

... but aren't the harmonics from the Si5351a already >10dB down on the fundamental, so the over all spurious emissions after the 40dB suppression of the LPF are already much greater than the 43dB required by your USA regulations?

The 'optlowpass' filter sure is impressive!

73, Bob  ZL1RS



Re: Firmware update with USBasp

TrueBlue
 

Is Extreme Burner AVR downloadable through anywhere but fishy third-party sites?  I can't find one so far.

Re: [FIRMWARE] Problems installing USBasp

TrueBlue
 

On Tue, Dec 26, 2017 at 10:38 pm, Alan G4ZFQ wrote:
In Zadig the main things are "List All Devices" and the USB ID

If it is not seen on any USB port (try all and with no other USB device installed) then I guess it is faulty.
With "all devices" listed in Zadig, it still shows up as the "Unknown Device" that Win7 errored-out on.  When that entry is selected and the driver package for USBasp described in the instructions is installed anyway, it doesn't fix anything and I'm back where I started.  This shouldn't be this difficult.  I'm beginning to think this is a bad unit.

Re: LPF frequency curves #lpf

Paul Jorgenson KE7HR
 

I put a couple of documents about filters and design software, in the files section. I worked through the modeling and simulation of the stock 40 meter filter and an optimum design. Then, I constructed both designs and did measurements - for those curious about how the filters work and possibly why the parts variance has caused some to have low power output. The optimum design might be a solution for you (or not).

---------

Paul KE7HR

New file uploaded to QRPLabs@groups.io

QRPLabs@groups.io Notification <QRPLabs+notification@...>
 

Hello,

This email message is a notification to let you know that a file has been uploaded to the Files area of the QRPLabs@groups.io group.

File: 40-Meter-Optimum-LPF-KE7HR.pdf

Uploaded By: Paul Jorgenson KE7HR

Description:
40 meter LPF designs constructed and measured - KE7HR.

You can access this file at the URL:
https://groups.io/g/QRPLabs/files/LPF/40-Meter-Optimum-LPF-KE7HR.pdf

Cheers,
The Groups.io Team

U3, my gizmo, has died

cwebs@...
 

Gizmo, aka  U3 WSPR, has died. It ran great for three days and I went to turn it on yesterday and sparks flew, his eyes slowly closed, his leg gave a twitch and it was all over. Postmortem  performed today............ The microprocessor is dead but I ordered a new one a few days ago. . The DDS board is toast. Ordered a new one . The GPS board is toast. Ordered a new one. . The LCD readout is toast, but I had a spare.   I am making a new power supply.The power supply was the trouble maker. Sometimes when it rains there is lighting! All I can do is laugh and do it all over again. Carl  AB1ZI

New file uploaded to QRPLabs@groups.io

QRPLabs@groups.io Notification <QRPLabs+notification@...>
 

Hello,

This email message is a notification to let you know that a file has been uploaded to the Files area of the QRPLabs@groups.io group.

File: 40 meter Low Pass Filter example.pdf

Uploaded By: Paul Jorgenson KE7HR

Description:
A discussion of QRP Labs 40 meter LPF and a different design example.

You can access this file at the URL:
https://groups.io/g/QRPLabs/files/LPF/40%20meter%20Low%20Pass%20Filter%20example.pdf

Cheers,
The Groups.io Team

Re: #qcx #qcx

RN4HGS <rn4hgs@...>
 

Thanks Jim and Al!
It turned out an interesting feature - the frequency of the noise depends on the state of the decoder cw
RX on TX on - 7017.8
RX off TX on - 7016.3
RX off TX off - 7023.2
also depends Batt show on or off...
I use HBJ 12680 battery (idk contains or not it dc converter for power out)

Oleg RN4HGS