Date   
Re: U3S /5W PA on 2M

KEN G4APB
 

Yes, 0.5W is all I managed to achieve out of the '5 watt' PA. Was more 'acceptable' than the 20mW barefoot that I was getting before I added the PA.
I did try a 2N4427 driver instead of the BS170 and got almost 1 watt out but it (2n4427) overheated and blew during experiments. I have not changed any caps. There comes a point in experimentation when I stop and just use the kit. 

If anyone can do better, lets hear from them...

73 Ken G4APB

Re: #QCX Broken ATmefa328P and data #qcx

Y Ichikawa
 

By the way, there are 10m/12m in BAND select, but can not you use this?
Of course it is after designing and changing the LPF.

Afterwards, as usual, when you turn on the power, it remains box display.
However, pressing the tuning knob a long time came to start.
But I think that this is not the original specification.
Although I displayed Band Select, I set it to 17 m by turning the tuning knob and can not set it even by pressing Select button.
If you turn off the power without setting it, it becomes 0.000.00 MHz.
I can not return to the initial state because (7.8 Factory rst) on the setting screen can not be displayed.
.

Please help me.

Can't transmit with RIT #qcx #firmware

Richard G4TGJ
 

I think it's a known issue that when you have set RIT you can't transmit. Has this been fixed? I've got 1.00e firmware and it's not in the version history for 1.00f. At the moment RIT is useless.

Re: U3S /5W PA on 2M

Alan de G1FXB
 



On 10/08/2018 10:50, Info wrote:

Ken,

You are saying 0.5W out of the 5W PA board?

That is not acceptable


It's perhaps more acceptable when put into the correct context.
How is the PA Kit advertised on the QRP Labs site?

5W HF PA

It can be used as the basis for you to modify, change and experiment, changing the surrounding RF de/coupling capacitors & inductors & PA device to allow use at VHF.


Alan

I have that same fet on my Ukrainian transverter, and get nearly 10W out

of it.

I will order a 'proper' fet for the U3S.  I agree that the 5W PA transformer is wrong for 2M.

You did not mention it, but all the caps involved with the circuit should not be 0.1uf.  I changed

mine to 1000pf.  Even the one from the synthesizer.

73

Glen K4KV



On 8/10/2018 05:35, KEN G4APB via Groups.Io wrote:
Sorry, that should say single WIND toroids, not single turn!!

Ken G4APB


Re: U3S /5W PA on 2M

Info <info@...>
 

Ken,

You are saying 0.5W out of the 5W PA board?

That is not acceptable.  I have that same fet on my Ukrainian transverter, and get nearly 10W out

of it.

I will order a 'proper' fet for the U3S.  I agree that the 5W PA transformer is wrong for 2M.

You did not mention it, but all the caps involved with the circuit should not be 0.1uf.  I changed

mine to 1000pf.  Even the one from the synthesizer.

73

Glen K4KV



On 8/10/2018 05:35, KEN G4APB via Groups.Io wrote:
Sorry, that should say single WIND toroids, not single turn!!

Ken G4APB

Re: U3S /5W PA on 2M

KEN G4APB
 

Sorry, that should say single WIND toroids, not single turn!!

Ken G4APB

Re: U3S /5W PA on 2M

KEN G4APB
 

Hi Paul,
I have a U3S with OCXO and 5watt PA running on 2m.
Mods are;
1) Single BS170 U3S PA with single turn toroid (not trifilar).
2) BS170 PA running at 9volts. Output connection to LPF cut and connected directly to 5watt PA input (no LPF). Bias set for this device max out then backed off a little to prevent overheat. I always have small heat sink on these devices too.
3) RD15VF1 device on the 5watt PA (note different pin layout instructions). SINGLE turn 10turn toroid (not trifilar as supplied).
4) Po from 5watt via fed back to 2m LPF input (and relay switched board in my case).
4) Bias set on this device for just taking a few mA with no RF drive.
5) 13.5 volts to 5 watt PA.
6) In menu, SHAPING set to 10  140.
7)  Po = 0.5 watts on 144MHz.

Warning, heat from the PA will cause frequency drift. You need to physically separate them, and maybe try a few other frequency stabilising tricks as well.

73 Ken G4APB

Re: QCX from 9.6V supply - worth trying? (plus low voltage sidetone issue)

John VA7JBE
 

Hi Seth,

If you'd like to use just 4 NiMH AA cells then you might try the Ikea Ladda cells (basically eneloop pro cells, 2450 mAh, 4 for <$10) paired with the DC-DC boost converted designed by DK3IT for his SOTA go-box.  This will bump you up to 12V for at least a few hours, given the low consumption of the QCX. 


DC-DC filtered boost converter

https://github.com/mfhepp/gobox-power

Ikea Ladda AA batteries
https://www.ikea.com/us/en/catalog/products/70303876/

Re: 3D printed case

Glen Sr
 

Jess. I will take the case if still available. Glen N8WE

-----Original Message-----
From: Jess Gypin
Sent: Wednesday, August 8, 2018 11:12 PM
To: QRPLabs@groups io
Subject: Re: [QRPLabs] 3D printed case

Still up for grabs.

On August 3, 2018, at 2:30 PM, Jess Gypin <ontarget1911@...> wrote:

I have an excess 3D printed case that I will send to some one for postage.

Jess AE0CW

Re: Blew up QCX with GPS - repair advice?

Alan de G1FXB
 

Another possible if heat-sinking hasn't / doesn't save it,
is to perhaps lessen the dissipation of the PA*.

The easiest being reducing the input voltage while using high duty cycle modes
 such a WSPR ??

* Class E output stages by their nature can be subseptable to component failure through excessive Vs caused by many external factors.
Inc antenna mismatch etc.


Alan

On 08/08/2018 23:36, Alan de G1FXB via Groups.Io wrote:

Is the warning contained in section 4.24 Beacon menu in the assembly manual relevant?


Alan


On 08/08/2018 23:24, BobVA wrote:
On Tue, Aug 7, 2018 at 06:04 PM, Kent Vanderploeg wrote:
Just following up on my progress and to see if Bob has had any luck getting his going again.
  I'm afraid I'll not be much help.  Replacing Q1-Q6  got me back to about 3.5w into a dummy load on 20m at 14v (not a great wattmeter, so take that with a grain of salt).
    I then reconnected all the WSPR bits but unfortunately forgot to peak my small loop on the WSPR frequency before transmitting (it was close, but...), so that took out the finals yet again (shorted this time).
     I replaced just Q1-3 and Q6 again which got the RF back, and then *carefully* set it and the antenna up for WSPR.  It transmitted happily for a couple of hours, putting out about three watts. 
   Then some other failure ensued that resulted in a blank display.  After a cycling power I had no RF again, so I'm beginning to suspect I've either got another fault in the radio that is causing the finals to fail, or it *really* doesn't like something about my antenna setup. 

  73,
   Bob


Re: QCX 40 - Need help with BPF alignment

jmcf2005@...
 

Hi Richard,

Yes, the windings on T1 are all in the same direction, as I followed the procedure in the manual. I scraped off the enamel and checked continuity before soldering. After soldering I checked it again by touching the probes onto the solder blobs.

Thanks,

John

Re: QCX 40 - Need help with BPF alignment

Alan de G1FXB
 

Hi John,

Something to bear in-mind I'm doing this blind as I have not built a QCX,
people who have, need to correct my statements if wrong!

H'Mmm
C1 seems OK.
TX Power OK.

Overall the peaks seem low, past discussions have indicated people report scaling factors of 8/9, but as you say its dependant on AF gain position for all but C1 alignment.
There is a voltage table at the end of the Assembly Manual, section 6.4
The measurements were made using the QCX inbuilt DVM which has a lower I/P impedance than most stand alone meters.
At first sight the table is a little strange because it doesn't start at IC1 but the order it is made, sets the basic requirements and then follows the signal path through the different circuits.
For sake of convenience it would be best to use the inbuilt, unless you have any concerns to its accuracy.
Oscilloscope trace & levels can be found on the https://www.qrp-labs.com/qcx/qcxtrouble.html troubleshooting web page. If you have access to a scope, through a friend if necessary.

A quick bit of background,
What version kit have you, Firmware revision?
The kit otherwise went together OK and raised no queries?
If possible a couple of photo's of top & bottom of the PCB just incase it's possible to spot something.

Alan


On 09/08/2018 21:26, jmcf2005@... wrote:

Hi Alan,

Thank you for your help. Following your suggestions, here’s what I found;

  1. I checked the continuity of all the windings on T1, as well as L1, L2, L3 and L4. All were good.

  2. I checked the Peak BPF and while adjusting it noted that with C1 fully meshed, the maximum amplitude was 4, with 6 large segment bars on the scale. As I rotated C1 to fully open, the number of bars increased from 6 to 13. It didn’t look like a sudden jump.

  3. I then checked the phase adjustments with the volume set at about 50%.

I-Q Balance was an amplitude of 6 with 50% of the bars

Phase Lo was 5 with 50% of the bars.

Phase Hi was 6 with 50% of the bars.

I checked the transmit power with a meter into the dummy load and it was exactly 4w.

You also mentioned doing voltage checks. Are there any instructions somewhere on the procedure for that?

Thanks again.

John

 

 


Re: QCX 40 - Need help with BPF alignment

Richard G4TGJ
 

The voltage check procedure is in the manual. The given voltages assume you are using the built in meter. If you use an external DVM you will find that some of the readings are much higher. This is because the internal meter has quite a low impedance and will pull some of the voltages down.

Are you sure all the windings on T1 are OK? Firstly, are they all in the same direction? If you followed the procedure in the manual then they should be OK. Then you need to be sure that the wires are correctly soldered. I found that although I got correct continuity by probing the ends of the wires, they weren't actually soldered properly to the board. I had to apply more heat to burn off enough enamel. Even if the windings aren't quite right you should be able to hear something.

Re: QCX 40 - Need help with BPF alignment

jmcf2005@...
 

Hi Alan,

Thank you for your help. Following your suggestions, here’s what I found;

  1. I checked the continuity of all the windings on T1, as well as L1, L2, L3 and L4. All were good.

  2. I checked the Peak BPF and while adjusting it noted that with C1 fully meshed, the maximum amplitude was 4, with 6 large segment bars on the scale. As I rotated C1 to fully open, the number of bars increased from 6 to 13. It didn’t look like a sudden jump.

  3. I then checked the phase adjustments with the volume set at about 50%.

I-Q Balance was an amplitude of 6 with 50% of the bars

Phase Lo was 5 with 50% of the bars.

Phase Hi was 6 with 50% of the bars.

I checked the transmit power with a meter into the dummy load and it was exactly 4w.

You also mentioned doing voltage checks. Are there any instructions somewhere on the procedure for that?

Thanks again.

John

 

 

Re: QCX 40 - Need help with BPF alignment

Alan de G1FXB
 

One other thing,

Whilst adjusting C1 can you see it approaching a peak, from fully meshed Or is it a sudden "all or nothing" peak?

(The trimer is polythene construction, and thus requires careful application of heat during soldering otherwise it's possible to melt the dielectric.)


Alan


On 09/08/2018 17:45, Alan de G1FXB via Groups.Io wrote:
If it were me, rather than the order perhaps it should be.....

1/.    Continuity check the windings of all the toroids.
            (The LPF is not only for the TX it is also in series with T1 BPF on receive. And needs to pass the alignment signal (and off air signals) builders not having stripped the enamel sufficiently has caught people out in the past)
           
2/.    If that tests OK, carry on to the Phase adjustments do they show  good response?

3/.    Is TX Power OK?

4/.    Finally, Voltage checks, to see if they give a pointer to a stage that requires further investigation.

Alan




On 09/08/2018 17:10, jmcf2005@... wrote:

Hi,

I just finished building my QCX 40 and I’m having problems with the BPF alignment. I found that it peaks with a maximum amplitude value of 4 with the bars almost to the right of the display. At that point the C1 plates are fully open.


I read a recommendation that it’s best to do this step with a dummy load attached, so I used the QRP Labs dummy load.  This time I found the maximum amplitude value was only 3, with the bars again all the way to the right and the C1 plates still fully open at that point.

Per the instruction manual, I removed 5 turns from the secondary 3 winding of T1. However, doing that hasn’t changed anything, as I’m still getting the same results as above, with the peaking occurring when the C1 plates are fully open.

As I live in an apartment, I tried connecting the QCX to a magnetic loop antenna outdoors both before and after the change to T1, but no signals were received. I don’t know if that’s just due to my location, so I intend trying again in a more open location over the weekend.

However, I’d like to try to see if there’s anything else I need to due to sort out the BPF alignment before then. Any help or advice would be appreciated.

Thanks.

John

W6KJL



Re: QCX / 17m Ordered

Mark G6PMN
 

many thanks for posting up the photo Bill, much appreciated. 

73 Mark G6PMN 

Re: QCX 40 - Need help with BPF alignment

Alan de G1FXB
 

If it were me, rather than the order perhaps it should be.....

1/.    Continuity check the windings of all the toroids.
            (The LPF is not only for the TX it is also in series with T1 BPF on receive. And needs to pass the alignment signal (and off air signals) builders not having stripped the enamel sufficiently has caught people out in the past)
           
2/.    If that tests OK, carry on to the Phase adjustments do they show  good response?

3/.    Is TX Power OK?

4/.    Finally, Voltage checks, to see if they give a pointer to a stage that requires further investigation.

Alan




On 09/08/2018 17:10, jmcf2005@... wrote:

Hi,

I just finished building my QCX 40 and I’m having problems with the BPF alignment. I found that it peaks with a maximum amplitude value of 4 with the bars almost to the right of the display. At that point the C1 plates are fully open.


I read a recommendation that it’s best to do this step with a dummy load attached, so I used the QRP Labs dummy load.  This time I found the maximum amplitude value was only 3, with the bars again all the way to the right and the C1 plates still fully open at that point.

Per the instruction manual, I removed 5 turns from the secondary 3 winding of T1. However, doing that hasn’t changed anything, as I’m still getting the same results as above, with the peaking occurring when the C1 plates are fully open.

As I live in an apartment, I tried connecting the QCX to a magnetic loop antenna outdoors both before and after the change to T1, but no signals were received. I don’t know if that’s just due to my location, so I intend trying again in a more open location over the weekend.

However, I’d like to try to see if there’s anything else I need to due to sort out the BPF alignment before then. Any help or advice would be appreciated.

Thanks.

John

W6KJL


QCX 40 - Need help with BPF alignment

jmcf2005@...
 

Hi,

I just finished building my QCX 40 and I’m having problems with the BPF alignment. I found that it peaks with a maximum amplitude value of 4 with the bars almost to the right of the display. At that point the C1 plates are fully open.

I read a recommendation that it’s best to do this step with a dummy load attached, so I used the QRP Labs dummy load.  This time I found the maximum amplitude value was only 3, with the bars again all the way to the right and the C1 plates still fully open at that point.

Per the instruction manual, I removed 5 turns from the secondary 3 winding of T1. However, doing that hasn’t changed anything, as I’m still getting the same results as above, with the peaking occurring when the C1 plates are fully open.

As I live in an apartment, I tried connecting the QCX to a magnetic loop antenna outdoors both before and after the change to T1, but no signals were received. I don’t know if that’s just due to my location, so I intend trying again in a more open location over the weekend.

However, I’d like to try to see if there’s anything else I need to due to sort out the BPF alignment before then. Any help or advice would be appreciated.

Thanks.

John

W6KJL

Re: QCX / 17m Ordered

Bill, W3WTD
 

Here's a photo of my QCX-17.  Output power is as advertised.  T1 is spaced to as to fit the mounting holes.  Things may get a little tighter when I start on the QCX-40 that arrived last week....

73, Bill W3WTD

Re: Need help

Jack K9VLX
 

I removed the BS170’s and the lC3 and powered up but didn’t get any data in the display. It looks like there’s more problems. Looking at IC1 it looks like more than my ham fist should handle so I think ordering a new QCX would be the best way for me to go. .......... sorry this posted by accident I hadn’t finished. Thanks Alan,Jim & Willy for you expert help, I will be adding the PA protection in the next one.

Jack K9VLX