QCX microprocessor startup

[email protected]

A frequent subject, dont see a path for me to pursue. Built qcx kit, December 2017 ship, group 2 board, made the three mods suggested (did RF choke pin 20 to 7 instead of Schottky). Start up was perfect all steps worked fine, heard signals, 20 meters,? noticed only 1.5 watts on transmit but assumed I would get to that later with output tweaking of toroids etc., otherwise fine. Turned it off, turned it on, nothing. Brightest screen just gives me the two rows of squares, etc. Voltage measurements compared to the table are all over the place. Checked 20 MHz osc. with scope, works fine. 5v, 12 v, seem to be where they should be, clk 0 and 1 are 9 mv with a dvm, no scope on that, various odd voltages on ICs etc, but assume without the LCD and microprocessor no point in worrying. None of the issues I have read about so far seem to get me started. I did replace both small chokes with my own older type (look like a 1/4 watt resistor) since both easily self destructed on removal, but no mods, no fancy step. Just need some direction and I will go there I guess.?
Cap
W0CCA

Re: wire jumpers PCB #u3s rev.3 #u3s

#21214

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Hi Martin,

On 28/01/2018 22:00, Martin Wilens wrote:

In the manual?assembly_u3s_r3_a4.pdf on page 10 there are several circled in yellow, the lowest is not clear to me.
Are the unnamed pinnes above +Pa +5V and Heat parallel with +Pa +5V and Heat? In that case I can connect the unnamed pins all three together and have the +5V pin free for the powersupply..

Flip the PCB over and you will see the unnamed terminals are on the same tracks as a named ones.
Short answer
yes you can connect +PA, +5v and Heat altogether. The unnamed terminals provide a method of creating tidy links
at the same time? allowing an easy method of reconfiguration should your requirements change at a later date.
See the diagram on page 11

Long answer,
It has being found since writing of the document:-
if you are using the OCXO option, using the same 5v supply as the MCU to feed the large current demands of the heater circuit
is generally not recommended and may give rise to frequency drift on your transmissions.
Even minute voltage fluctuations on the MCU and synthesiser supply voltage supply will give rise to this .
It is recommended to feed the Heater circuit from a separately stabilised supply due to its high current demands.

For the very best frequency stability then consider powering the +PA voltage from a separate regulated supply.
It also gives you an opportunity to utilise a higher voltage regulator to increase RF power out if desired.
(Subject to adequate heat sinking of the PA device(s)).
See the section entitled 'Higher power output' near the bottom of page 16

Hans has produced FAQ and notes and there many threads on this forum regarding problems & solutions to the different causes of frequency drift.

@Hans: is it possible to create a scematic drawing? including W0, W1, W2, W3, RF RFi and RF0?
It would be a bit more clearifying (at least for me)

read the section on 'Hardware Requirements' Starting near the bottom of page 10 first.

Then if you use a DVM / VOM meter to trace the links you should find, Links W0, W1 & W2, W3 are in parallel to the relay position RLY0 changeover contacts.

The rule is if you are not fitting a relay in this position as you are not using the optional relay switch PCB then you should add the links
to maintain continuity from the PA to the U3S on-board LPF and then again onward from the LPF to the RF pin.
Fit a relay, fit no links as this will override the function of the relay contacts!

The antenna connection required for the U3S in it's simplest form,? is to the RF Pin when no optional relay switch PCB is in-place.
As shown on the diagram on the bottom of page 15.

If you are using the optional relay switch PCB, there are several different filtered RF connection options, to terminal pins or different onboard connector options.
This is described in that modules assembly instructions.

Presently the only time a? 'kit builder' is required to make any connections to the 2x5 pin Backbone connector,
that interconnects the stacking modules is when using the 5W PA Option .
As detailed in that modules App Notes.
(which contains the signal pins RFI(n) & RFO(ut) you mentioned)

Thanks

I hope that helps to clarify your questions.
regards Alan

Re: r33 36k resistor

#21213

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As to enclosures, I didn’t get to it quick enough and my 14 year old ham made one out of Lego’s. Only temporary I hope.

Don ?WB9STS

Show quoted text

On Jan 27, 2018, at 1:54 PM, bill1973ham@... wrote:

Thanks everyone for your replies. I dug deeper into that junk box and came up with a carbon resistor and it measured 36 k exactly so i used it. now I am torn between finding a box or mounting every thing on the board. I guess I will put everything on the board for now.
Thanks again.?
Bill N8WS

Re: Display flashing U3S

#21212

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Hi Mario,
Have you tried squeezing the two boards together,
in rare instance the interconnecting plug / socket can oxidise and cause a poor connection?

Also as noted in the assembly manual,
the PCB stand-offs supplied require an approx 1mm spacing be made between one half of the connector
and pcb to ensure a good connection of the connector.

regards Alan

On 26/01/2018 21:46, df8dl@... wrote:

Show quoted text

Hi all,

running my U3S for many weeks without problems. After this time, the display starts flashing. This behavior starts in the right part of the display, than the hole unit shows the problem . (It wasn‘t possible to read something).? I changed the device and it works perfect for some days. After this time? the new display shows the same problem again. Any ideas? Thank you!

Vy73 Mario DF8DL

U3S error 5

Wally Wolfe

#21211

I assembled the kit (rev 4) without problems, tested per the manual with ~.5 watt output, installed gps module and got good locator,? calibrated WSPR and was received and decoded properly on my higher end ham rig.? Well regulated linear power supply.? There was much joy.? Set up with a good 1.2:1 dipole antenna and left it running overnight.? Next morning, display reads Error 5 (or maybe it is Error S).? Doesn't respond to the buttons, no RF out, still lights the gps LEDs but display stays at Error 5.? Nothing looks like it let the smoke out, no burned traces on the boards that I can see, IC2 on the TXCO gets warm but not excessively warm.? I suspect something scrambled in the processor, but I don't know how to test that.? Ideas?? What next? Help!

Wally
KF7EB

wire jumpers PCB #u3s rev.3 #u3s

#21210

In the manual?assembly_u3s_r3_a4.pdf on page 10 there are several circled in yellow, the lowest is not clear to me.
Are the unnamed pinnes above +Pa +5V and Heat parallel with +Pa +5V and Heat? In that case I can connect the unnamed pins all three together and have the +5V pin free for the powersupply..

@Hans: is it possible to create a scematic drawing? including W0, W1, W2, W3, RF RFi and RF0?
It would be a bit more clearifying (at least for me)

Thanks

Re: key short the first dash

#21209

Thanks Alan, sounds like the thing to do on the short term until the bug is worked out with the keyer.

Re: key short the first dash

#21208

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Hi A1aop,

The solution to differing standards of key wiring has being reported before.
The solution for straight keys / Keyers is to build a short adaptor lead, a 3.5mm line mono jack socket connected to just the Tip & Sleeve
of a stereo 3.5mm jack plug and all is resolved, with the correct selection also in setup menu.
And you can retain the use of the key with your previous radio(s) interchangeably.

Hope this helps, Alan.

On 28/01/2018 19:04, A1aop via Groups.Io wrote:

Show quoted text

Having the same problem no matter what paddle I use. Haven't tried an external keyer since the mono cord from the keyer shorts the rigs jack, unless I'm doing something wrong.

Re: key short the first dash

#21207

Having the same problem no matter what paddle I use. Haven't tried an external keyer since the mono cord from the keyer shorts the rigs jack, unless I'm doing something wrong.

making mods to the clock kit #clock

#21206

The clock and GPS kits are neat. Of course, I can't leave well enough alone so I am working on a portable gps/clock powered by four AA batteries with front panel switches to turn off the GPS and backlight and pots to control contrast and backlight brightness. From the various data sheets, it looks like the GPS board needs about 35mA while acquiring a signal and 25mA while tracking and the clock board, with the backlight turned off, needs 5mA. I think that the backlight requires 150mA at full brightness but different data sheets seem to say different things so I am not sure, So, question one:? can anyone confirm my estimates with measured currents used by GPS and clock kits?

Second question: since the GPS board uses 74ACT08s to drive the signal lines, I can drive more than one TTL load with the 1PPS and TxD lines, right?

Third question: I am guessing that the clock kit iinterrogates the GPS to get the GGA data frame. Is there any reason why I can't passively listen for decode that frame with another device?

73 de bill K7WXW

Re: key short the first dash

#21205

Hans, is there a solution to my problem?

success!

#21204

I've got 20m QCX S/N 924 working. I was getting the line of blocks, and L5 was showing 20MOhms. I replaced it with a 100uH on hand and fixed the problem. I've aligned it but it's late now. No mods -- maybe later.

Looking forward to putting it on the air tomorrow.

73

Bill

KA3BMU?

Re: AM Broadcast Interference QCX

#21203

Thanks Jerry,

All great ideas. I will try them.

I tend not to ground the filter since I don't always have it in line, I sometimes MW dx. Shack is on the second floor, though I do have a ground line down to the yard. So far I've made solid QSOs in spite of the interference, since most of us hard core CW guys have the built-in filter between our ears, hi.

73

Jerry N3HAM

Re: AM Broadcast Interference QCX

#21202

Yes the interference goes away. Looking to eventually case it up, I do have a tin that it fits in, just need to figure a way not to butcher it up. It would make a nice companion to my PFR3 for park portable.

Re: AM Broadcast Interference QCX

#21201

They are listed at 50K, but not sure it's that high according to a search on the station. Think they may actually be going off air and selling the transmitter site for developement. Last community group meeting mentioned something about that area, and I'm gathering more info. My other HF rigs not as bad with the BC interference. My FT990 has some issues with FM though, some images sporadically throughout the HF range. I live near a very large antenna farm,the proverbial Radio Hill, where most of the FM and TV broadcasters have teir towers.?

Re: Ultimate3S : huge frequency drift

#21200

Thanks all for your answers. These confirm the issue I experience?is not due a technical failure / malfunctioning?but more due to structural reasons, which I'm going to investigate.
73 and thanks for your help,

Ga?tan, ON4KHG

Re: Receiver thump

#21199

Happy dance? ? sure was too quick to replace that 10 pf

989.16uf works much better.

Sure getting skilled at replacing parts especially this one

Many tx for your support

P

Show quoted text

On Jan 27, 2018 2:13 PM, "John Pagett" <john.pagett@...> wrote:

Phil,

Are you working on the right capacitor?

The 10uF (microfarad) is a black electrolytic capacitor.

You have to replace it with 100nF (nanofarad) - otherwise known as 0.1uF (microfarad).

10 and 100pF capacitors are much smaller values.

Apologies if I'm teaching you to suck eggs..

73
John
G4YTJ

Sent from my iPad

On 27 Jan 2018, at 19:04, Phil Moorey <pmooreyca@...> wrote:

No cigar. Removed the 10 pf cap, installed a 100pf but no luck
There is a change? ?it seems the start of the cw note is where problem is

On a dash its more noticable? once the first dash has started the rest are clean and clear. I believe i can even have a very slight pause between dashes and its still clear,

I must be barking up the wrong tree.
Using apple ear buds, iambic b, semi break in, is better than full break in.

Getting good at replacing components but dont want to do it too often.

Appreciate your support

P

On Jan 25, 2018 3:51 PM, "Frank PA7F" <F.e.vandijk@...> wrote:
Phil, you have to remove the 10 uF cap. See message thread #20843.

Frank PA7F

Re: Might be useful for testing etc - The LED-O-METER

#21198

Thanks Alan.

I deleted the old message because there is no edit menu on this group, so some readers may be confused.

Revised message is here? - /g/QRPLabs/topic/signal_trace_for_qcx_u3/9406138?p=,,,20,0,0,0::recentpostdate%2Fsticky,,,20,2,0,9406138

73 de Andy

Re: r33 36k resistor

#21197

Thanks everyone for your replies. I dug deeper into that junk box and came up with a carbon resistor and it measured 36 k exactly so i used it. now I am torn between finding a box or mounting every thing on the board. I guess I will put everything on the board for now.
Thanks again.?
Bill N8WS

Re: Might be useful for testing etc - The LED-O-METER

#21196

开云体育

Great idea Andy,

Build it in a disused clear biro pen.

It should get used more often than a screwdriver in the tool kit.

regards Alan

On 27/01/2018 19:14, Andy G0FTD via Groups.Io wrote:

Show quoted text

Just been reading about constructors trying to trace RF in their circuits.

Here's a neat trick to help fault find, the LED-O-METER.

All you need is 2 x 1N4148 or similar diodes (any old diodes will do really), and any old LED.

See the photo -

The LED-O-METER has a little flying tail to it (a bit of wire !) which you tap on to any point on the PCB to see if there's RF there (at least a few hundred milliwatts).

Or use it as a field strength meter with a longer wire attached, or with a simple connection to the output to tell you that your U3 / QCX ot any tx is transmitting.

Sensitivity can be controlled by using series capacitance or resistance in series with the flying tail part.

The LED-O-METER is a single ended devicce, no need for an earth.

73 de Andy