Date   

Re: Group storage

Alan G4ZFQ
 

What this shows is the difference between past usage of groups like this and the present.
The Softrock group has for 14 years done much the same as this group, supported kit construction. It has 8500 members, is now in it's twilight years, little used.
The present groups.io statistics show
Using 170MB for photos storage
Using 1.2MB for attachments storage.
Using 149MB for files storage.
There has never been cause to delete files... People just did not post them or made an external link.

I guess it's smartphones?

73 Alan G4ZFQ


Re: RX Module - I/Q balance question #rcvr

Alan G4ZFQ
 

* What was needed it was re-soldering of IC1 (SMD one)
Lexa,

Well done, a tricky job.

Anyway I am surprised that system with such serious "fault" was somehow working - I thought that in SDR everything has to be 100% to have some output -

No, there are two outputs, I+Q.
I could say that there is no difference if you use I or Q, all signals are received!
BUT Both I and Q outputs are required to separate signals from below the Local Oscillator from those above the LO.

73 Alan G4ZFQ


Re: Group storage

Floyd Hollister <fhh11@...>
 

Jack,

$2200/year sounds way too high.  How much storage would that supply compared to what you are using now? If the cost was $220 /year, I think the membership would opt for it.

Many good points have been made about the need for purging files of useless or outdated material is a good one but it requires someone to do it.  

There must be some affordable way that Group data can be stored and retrieved using a good search engine.   

73, Floyd K2DUV


Re: RX Module - I/Q balance question #rcvr

Lexa, OK1DST
 

I/Q balance problem SOLVED!

What was needed it was re-soldering of IC1 (SMD one) where probably one of outputs has bad contact. It was little bit "surgery" but with success :-)
Now I can see only valid traces and I/Q balance automatic system is working etc...

Thanks to all for advices and help - here or directly!

Good luck and 73!

Lexa, OK1DST

P.S.: Anyway I am surprised that system with such serious "fault" was somehow working - I thought that in SDR everything has to be 100% to have some output - learning more, again - thanks, Hans! :-)


Re: RX Module - I/Q balance question #rcvr

Erik Kaashoek
 

Thanks, I tried rocky before but could not get it to work, tried again and now I can observe the I/Q unbalance. 
Phase: Lineair from -1 (-48kHz)  to +1 (+48kHz)
Amplitude: Error below 0.2%, dot cloud over full audio range (noise limit?)

I should have matched the filter capacitors
--
Erik@Home


Re: QCX 20 No output...New build

Paul
 

Hi Jim

Thanks for taking the time to answer my question.
Just so I don’t make any “newbie” incorrect assumptions here is what I have done following your suggestion.
Using a separate multimeter one probe on the negative 12v input.
2nd probe checked for continuity on all 3 points of Q6 with the radio powered off.
To clarify I am looking at the back of the board with the BNC connector top left.
I think I am right with my pin layout, pin1 top, 2 middle and 3 bottom?
Readings are
Pin1 0 ohms 
Pin2 .47 ohms
Pin3 open circuit

Thanks again Paul

From: <QRPLabs@groups.io> on behalf of James Daldry W4JED <jim@...>
Reply-To: "QRPLabs@groups.io" <QRPLabs@groups.io>
Date: Saturday, 26 January 2019 at 21:05
To: "QRPLabs@groups.io" <QRPLabs@groups.io>
Subject: Re: [QRPLabs] QCX 20 No output...New build

Hi, Paul

Q6 either is open, its collector is shorted to ground, or both. Check for zero ohms to ground from the collector. It should check open. If short, you either have a "whisker" short or one or more shorted FET's. If the collector reads shorted to ground pull the FET's and see if the short goes away. Once the short is cleared you'll need to replace Q6.

Jim W4JED

On 1/26/19 3:19 PM, paul.hadfield@... wrote:
This is the first kit of any kind I have built and everything has been a vertical learning curve.
On completion everything appears to work as expected just no power out.
I have checked continuity and re soldered all toroids, and they are fine.
Using the built in power meter I have checked for output at Q1,2 and 3 as suggested in the manual. No output at these points.
Having spent most of Saturday afternoon searching through posts to point me in the right direction I have been looking at the voltages with Q6.
Now I think something is wrong here but but not sure, and don't know where to begin correcting the situation if it is wrong.
Using the built in V meter I am seeing
Pin1 Emmiter , 11.45v key on or off
Pin2 Base, 11.1v key off and 7.46v keydown
Pin3 Collector 0v key on or off.

Any help would be appreciated as I would love to get it all working 100%

Paul


Re: Got my QCX 40 working but very low volume in the headphones

Alan de G1FXB
 

Don,
Bobs question is a good one....
If the targets & feel of gained during alignment was that descried in the manual, It's a confidence check that the RX stage is performing correctly while using the known built-in test equipment.
It is common to have to repeat the trimmer adjustments several times as they are interdependent.
Alternatively when tested a typical build yielded Receiver MDS of -121 dBm (0.2 µV), and at least 50dB of unwanted sideband cancellation
if you have access to equipment, how does yours compare?.

as per the manual write-up the built in AF stage is optimised to drive cell phone style ear buds, expect to add external af amplification to drive difficult loads / speakers etc

If in your previous kit building experience you expect the QCX to behave / sound like a classic SA602 / LM386 lineup it will not, it has a very low self generated noise /  large dynamic range & IP3
Described as Weak signals will come out of the silence, rather than being in the noise?

Alan

On 26/01/2019 22:18, Don Huffstetler via Groups.Io wrote:
It was aligned by a great builder

Don



-----Original Message-----
From: Chopper <bob@...>
To: QRPLabs <QRPLabs@groups.io>
Sent: Sat, Jan 26, 2019 2:09 pm
Subject: Re: [QRPLabs] Got my QCX 40 working but very low volume in the headphones

When you went through the alignment procedures, did you get the expected max or min values or just the highest and lowest points. 


Re: RX Module - I/Q balance question #rcvr

Alan G4ZFQ
 

better than 40 dB "ghost"  surpression on the whole 192kHz audio  band is considered good!
Erik

I've no figures but Skimmer uses the same IQ adjustment as Rocky http://www.dxatlas.com/rocky/Advanced.asp It compensates across the bandwidth, not in one place.

73 Alan G4ZFQ


Re: I Burned Up My U3S

Al Holt
 

I had that happen on an older rev PC board and a couple of traces connected to the processor had to be repaired due to over current. I used some thin gauge 'wire-wrapping' wire, but thought maybe one of those conductive ink PC repair pen might also work. I replaced the processor with a new one.

The Si5351 was also bad. Replacing the chip was a bit tedious, but can be done. It's going to depend on your skill level, tools and patience.

I sourced replacement parts from Mouser. Flashing the ATMega chip was a good learning experience! Good luck with your repair!

--Al
WD4AH


Re: RX Module - I/Q balance question #rcvr

Erik Kaashoek
 

And be aware that getting better than 40 dB "ghost"  surpression on the whole 192kHz audio  band is considered good!
You can get 70dB surpression on one frequency but never for the total
--
Erik@Home


Re: Group storage

Alan Richmond
 

Is the cost of extra storage a one-off cost, or an annual one?

Alan

GU3ONJ


E & O E


Re: RX Module - I/Q balance question #rcvr

Lexa, OK1DST
 

Hi Erik,
great idea to go w/o output transformers! I will try asap.
And I was not sure if I can get output with only one channel, it is new to me and also good to check!

Thanks for now and I will report later on....
73
L. -dst-


Re: RX Module - I/Q balance question #rcvr

Alan G4ZFQ
 

I am not able to perform automatic I/Q balance with my RX module and looking for any advices/experiences. I am quite sure I made T3 correctly with correct orientation and phasing (as unit seems to produce correct I/Q signals). I do not know if there can be some other source of so big phase/gain shift to be out of range of this automatic algorithm in CW skimmer or...?
Lexa,

Perhaps you could do Eric's modifications https://groups.io/g/QRPLabs/message/30208

unit seems to produce correct I/Q signals
I wonder why do you say that?
Skimmer has a very good phasing system, I would expect some sort of balancing to show even with the cheap transformers.
If Eric's modifications do not help check all voltages on the ICs. If there are large variations it may point to a fault.

73 Alan G4ZFQ


Re: RX Module - I/Q balance question #rcvr

Erik Kaashoek
 

I'm also using the RX module as a SDR rx either standalone or as the IF for higher frequencies
This is what I did, it may help you or not.
First check you have actually I AND Q output. If one channel is not working you will get output but many "ghosts" 
I removed the output transformers. There where big frequency dependent amplitude differences between the two transformers and I was unable to get to acceptable phase/amplitude balance.
I also remove the filter capacitors (R3-R6) and replaced them with 2.2nF capacitors to get a more flat output, minute differences between the original capacitors again made balancing the whole audio band impossible.
--
Erik@Home


Re: Prog Rock board voltages

Alan G4ZFQ
 

I did, and got +5.3V, and +3.7V, at the locations specified. Are these within spec?  And, if not, what needs correcting?
Hans has said before that the voltages are somewhat higher than nominal. I'm not sure about measuring resistances when fitted, other paths might be involved. If you use the formula for the regulator it comes out at around 5.15V. The 3V3 also calculates at around 3.6 so your readings are as expected.

73 Alan G4ZFQ


Re: I Burned Up My U3S

Hans Summers
 

Hi Mike


73 Hans G0UPL 

On Sun, Jan 27, 2019, 01:02 n0mpm <morgamp52@... wrote:
So even after I wrote myself a note to use 5volts on my new U3S, I got excited and cooked it with 12v !!
I know the ATMega is cooked, but wondering if everything else may be OK...I hope the 3.3 voltage regulator saved the Si5351A, and I checked out the LCD and it survived.
Questions:
1.  What else may be a gonner?
2.  I have a spare ATMega from a QCX.  Can I reflash it for the U3S or are the code plugs different?

At least I have plenty of snow to shovel to keep me busy if I have to order parts!
Mike. 


Re: I Burned Up My U3S

@CurtisM
 

Mike

I built a faulty power supply, and in my case only the controller was zapped. Research my call here to find Hans reply. I ended up ordering a spare basic kit to have spare parts, as well as a programmed controller. Of course if you have the right IC and tools, go for it.

Curt


Re: I Burned Up My U3S

Curt M.
 

Ugh....I think you just convinced me to install a little buck board inside of my U3S. I have a U3S that I use as a 5w beacon that requires 13.8v and I now have (2) QCX’s that are also powered with 13.8v. I have to keep telling myself to be careful with the other U3S that I use for WSPR and QRSS that runs on 5v because I’ll smoke it if I plug in one of the cables without the buck board on it. 

So if it’s any consolation you may have at least helped someone out. Hopefully you’ll be able to get yours back up and running. 

Curt M.


Re: Prog Rock board voltages

KI7MWA
 

Measuring R1 and R2, in the board, I'm getting 0.968kOhms and 2.82KOhms, which, should be giving me 1.25V(1+(2.82/0.968)) = 4.89V.  But I'm not good enough at reading schematics to conclude whether or not my measurements are being affected by some other part of the circuit (e.g. the LM317LZ).

I'm inclined to try adding some parallel resistance to R2, just to see if I'm understanding the voltage regulator part of the circuit.


RX Module - I/Q balance question #rcvr

Lexa, OK1DST
 

Hi friends,
I just finished Reciever module with ProgRock kit as LO.

My intention now is to use it as SDR rx for IF output from my K3 and TS-850 and use with CW skimmer.

So I have LO on 8.195x4, rf input directly to T3 (w/o band-pass filter) and cennected I/F out from K3 - everything seems to be OK.
CW skimmer is decoding signals but there are some "ghosts" from opposite sideband. Need for I/Q balance adjustment.
I jump into I/Q balance window (as part of CWSkimmer application) and no data there :-(  (there are empty graphs for phase/gain).

So I tried to connect PM-SDR unit (same levels, same input frq etc,, same cabling and sound card for I/Q,...) and I can see data plots in Phase/Gain graphs and calculated balance. And traces on CW skimmer are w/o ghosts and all is perfect.

So at summary - I am not able to perform automatic I/Q balance with my RX module and looking for any advices/experiences. I am quite sure I made T3 correctly with correct orientation and phasing (as unit seems to produce correct I/Q signals). I do not know if there can be some other source of so big phase/gain shift to be out of range of this automatic algorithm in CW skimmer or...?

Thanks for any advice...
73!
Lexa, ok1dst