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I've resurrected my old QRSS U2 V2.07 but having problems in getting out using WSPR mode.
Everything sets up correctly. Transmissions start spot on time (using GPS module). WSPR cycles through all the elements but there is no transmission that I can determine.
In the settings I set the DDS module Reference Frequency to 125.00MHz but upon returning to the settings, no matter after what elapsed time - whether after one WSPR cycle or many - the Reference Frequency has changed. Sometimes by a few hundred Hz and sometime by over 1.5MHz.
I've encapsulated the setup in a draft-free enclosure and with a fairly constant ambient temperature. But still the problem persists.
Is this a common problem (not that I can find much reference to it other than 'atmospheric' causes), but can anyone(s) offer a possible solution, please?
Many thanks in advance.
(Ah, you may well ask why am I using an old U2 version? Think of it as advance planning leading towards acquiring the latest kit).

Hi,

second solution - adding 10k resistor providing positive voltage to Q5 drain works as well, I got back to 1nF C33.

My power output was still low (below 20Vpp) so I removed all of the final BS170, checked the drive - nice, square 5Vpp, it was a bit distorted with the finals in place.

Decided to mount a few fresh 2N7000s (bought 50pcs some time ago) instead of BS170s. With just one in place, I got about same power output (~18Vpp). Mounted another one, keyed down, a flat line on the oscilloscope - and 0.8A of current consumption! Even after unkeying. 7805 got very hot, turns out 74ACT00 is now about 2,5 Ohms Vcc-Gnd and gets warm after connecting power. The second 2N7000 I mounted was apparently dead (shorted gate-source).

So, few days off until new 74ACT00 arrives and I get the necessary utilities to unsolder the old one, I hope the uC and Si5351 survived without damage. Also, 2SC(...) PNPs I bought do not work well in pulse shaping circuit - pulses begin very sharply and end too slowly (>10ms).

I think I spent more time than I should building it ;)

73 Olgierd SQ3SWF

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Oh!? Yeah... I missed the obvious there didn't I. I'm afraid I'm drawing a blank (no pun intended) then

73
NE5U

Mike

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Did you change the configuration to match the other LPF?
73
NE5U

MIke

When you use the GPS module the U3S can run a calibration routine, but rather than base the result on your operational transmit frequency you can specify a much higher frequency for the DDS to run at and get a more accurate compensating value at the end of the routine. I think I've got that right, but it is well documented by Hans.?

I have the park frequency set to ~130 MHz and try to run the calibration interval for somewhere between 2-3 minutes. I don't slew the offset very much and have it set for 2 or something like that.

Again, the software manual covers it pretty well.

73

Al Holt
WD4AH

I started to build the NorCal 40A Kit I bought ages ago from QRP Bob . I must have got the last one as he shut down shop?

--
Sent from Gmail Mobile

Gents,

I just finished building my first U3S and GPS receiver. Everything is
working great so far.

The operating manual is very overwhelming. I'm wondering what to use
for "CAL" and "PARK" settings for WSPR? I will only be using WSPR for
now.

Thanks
N1ESE

It's nice to see two of the major ham-oriented suppliers of these
parts, K5NWA and SDR-Kits, here in this thread. The Mitsubishi power
FETs are not available from hobbyist-friendly distributors like
Digi-Key or Mouser, so these companies are providing a valuable
service for those of us who just want a few parts. Unlike the parts
from eBay sellers, their transistors will always be the real deal.

Hi Ologierd,

I also replaced C33 (1nF -> 150pF) some time ago because I had the same issue. I did not see any oscillations since that.

It seems that many people had the same problem. Most of the dead Q6 might be caused by these oscillations because current was over 1A with no power output.

I wonder if the oscillations are specific to the 20m version (as mine and yours) or if all bands suffer from that issue.

Unfortunately one of the controller pins died during one of these "events". It is one of the keying inputs so the QCX is keying now all the time. At least I found a workaround while waiting for the replacement controller. I simply set initial keying speed to 0 and can use the QCX as receiver

73

Karsten- DL3HRT

As SDR-Kits we have supplied many genuine Mitsubishi transistors with zero complaints over the past 8 years.

Many people who initially buy on Ebay are disappointed with poor output and high current then buy the genuine article. They are then surprised how well the genuine Mitsubishi transistors works and annoyed how much time they have spent debugging their design or kit.
Shipping charges from the US are now very very high.? Our UK Airmail charges for a couple of transistors are? ?2.50 to European Customers and ?3.50 to outside Europe.? We even have a number of US Customers for that reason.

Jan G5BBL? ?

?

Hi Glenn,

I have tested the solution provided by Hans yesterday, to replace 1n C33 with 180pF - it works fine, no oscillation. I will try your solution as well as it seems a bit more elegant (retaining the original sensitivity), but...

I'm only getting 20 Vpp output on 50 Ohms which is?1 Watt!?- over 11V DC of supply on the drains, about 30V peaks while keying. Not sure what's wrong now. Drive on the gates looks correct, I removed one of the finals and it's still nearly the same output. Wondering if one of them may misbehave..?

I'll hapily use about 2-3 Watts output, looking at my previous screenshots 20 Vpp was the maximum I could pull out. Compared with FT-817 on the scope and yes, it's surely 1W output, I miscalculated the power using?wrong formula :(

But I'm closer and closer ;)

73 Olgierd SQ3SWF

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Chuck is checking out two inexpensive Chinese board manufacturers now.? Very inexpensive and fast turn around time, so time will tell if the project goes that way or needs to be improved.? He ordered boards from two suppliers and will be testing their durability.

Lee, w0vt

ability to hold the pads while heating at dam temperatures , - I wonder it depends on quality of copper clad and the micro thickness more than the quality of manufacture.

?Yes, you can say what qualty copper clad one selects.

?But we can also insist to use thicker micro as used in power supply designs.

regards

?sarma

?vu3zmv

regards
Sarma
?

On Sat, Oct 21, 2017 at 10:33 AM, <thompsonmichael724@...> wrote:

Ok, it wasn't me. I was looking and looking, haha. Thank you for the update.

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Yes.? Go to QRP-Tech on Yahoo Groups. ? There are a bunch of guys wanting to build a Norcal 40A that missed building one a few years ago.? A plain simple rig but updated with a keyer circuit.? Board has been layed out and now being tested. ? All pots and jacks are external to the board.? I think the board will be 4 x 3-1/2 inches. This is not a kit.? You supply all parts and Gerber file will be made available so anyone can order the boards from a PC Board Manufacturer using the Gerber file on file at QRP-tech.? This is a two sided board, solder masked, tinned and silk screened.? The Gerber file will be posted once all is in order.

Lee, w0vt

Ok, it wasn't me. I was looking and looking, haha. Thank you for the update.

Ok, it wasn't me. I was looking and looking, haha. Thank you for the update.

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Made a mistake.? The design is in the File Section at the QRP Tech reflector not QRP Labs.? (QRP Tech is a Yahoo reflector)

Lee, w0vt

Chuck ordered test boards from two manufacturers.? He wants to see how well the pads hold up to heat from each manufacturer.? Once the boards are proven, the boards can then be ordered using the Gerber file for the boards.? The Gerber file will be placed on this groups FILE section.?? Right now you can go over to the file section and look at the board layout.? It is a two layer board.

Lee, w0vt

On 10/20/2017 11:46 PM, thompsonmichael724@... wrote:

Wow! This is is great news! I almost pulled the trigger for a Wilderness version about ten times but waited and ultimately missed out. I'll have to keep my eyes peeled for posts from Chuck. Thanks for the info!

Mike N6MST

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Chuck ordered test boards from two manufacturers.? He wants to see how well the pads hold up to heat from each manufacturer.? Once the boards are proven, the boards can then be ordered using the Gerber file for the boards.? The Gerber file will be placed on this groups FILE section.?? Right now you can go over to the file section and look at the board layout.? It is a two layer board.

Lee, w0vt

Wow! This is is great news! I almost pulled the trigger for a Wilderness version about ten times but waited and ultimately missed out. I'll have to keep my eyes peeled for posts from Chuck. Thanks for the info!

Mike N6MST