Re: QCX burned up after connecting GPS

#21158

Was the QCX connected to the antenna at the time the GPS was plugged in?? If not, then the output transistors will be burnt out due to no load as the GPS unit will be "keying" the QCX.

There is not much that can go wrong with the GPS unit being connected as it is connected in parallel with the dit and dah keying circuit.

David

VK2JDR

Show quoted text

On 27 January 2018 at 14:44, Ted Dawson <teddydawson@...> wrote:

I finished my QCX and was enjoying it very much, I decided to build the GPS module and upon finishing it I connected it to the QCX. The rig just keys down the moment i connect the gps, I tried a few things like getting it in beacon mode then turning it off and connecting the gps then turning ur back on, well somewhere in this process the rig burned out , there was a puff of smoke and a small flash of light from under the LCD area. Before this the rig was fine doing CW, it was working well , something with the GPS module killed it. Just wondering how to troubleshoot this issue so maybe the rig would work again and scrap the GPS? Not sure where to start .

Thanks and 73

Ted, KG6AJH

QCX burned up after connecting GPS

#21157

I finished my QCX and was enjoying it very much, I decided to build the GPS module and upon finishing it I connected it to the QCX. The rig just keys down the moment i connect the gps, I tried a few things like getting it in beacon mode then turning it off and connecting the gps then turning ur back on, well somewhere in this process the rig burned out , there was a puff of smoke and a small flash of light from under the LCD area. Before this the rig was fine doing CW, it was working well , something with the GPS module killed it. Just wondering how to troubleshoot this issue so maybe the rig would work again and scrap the GPS? Not sure where to start .

Thanks and 73

Ted, KG6AJH

AM Broadcast Interference QCX

#21156

Just finished my 40m and had a first QSO. YEA! BUT, why is there always a BUT?? I'm hearing a nearby AM station (.25 mile) at 1540 khz in the background. Luckily it's a daylight broadcaster. Antenna is a 31 foot non-resonant wire vertical with 40 buried radials fed with low loss coax, a unun at the feed. I have an I.C.E. Broadcast filter at my station that doesn't seem to make a difference. Any ideas?

Display flashing U3S

[email protected]

#21155

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

Re: My QCX40 problem and Han’s new troubleshooting guide

Liam Kingsmill

#21154

开云体育

Kit for a scope useful for Han's troubleshooting guide.? If I spend about $50, there will be dough left to attend my 80th bday party.

I built a scope that was a $70 giveaway a few years back.?? Bandwidth high end is 200KHz, a recollection says.? And I gave a DIY Heathkit to a newbie HAM across the street 25 years ago.? I don't recall what happened to the Tectronics tube monster even before that.? The seller of the monster slept in a corner of a room in a two bedroom house that was otherwise filled with scopes.? But, I've seriously digressed.

Did I mention cheap?

Liam of Florence, Oregon.

On 01/26/2018 11:15 AM, Michael Lloyd wrote:

Show quoted text

Thanks Alan,?

Is that why the signal out of the BNC when using the Bandpass Adjust function looks odd (different than Hans signal. I know his wasn't 80m but I don't remember the band)

Yep, the 80m rig. Winter Field Day is this weekend. I'm going to actually be a Ham operator instead of a repairman this weekend and have a little fun.

I may put the 80m rig in a box and work on one of the higher frequency QCX rigs. I have one for 30m built except I need to wind the toroids. I've had so much practice T1 should be easy.?

--
73
NE5U

Mike

Re: My QCX40 problem and Han’s new troubleshooting guide

#21153

Thanks Alan,?

Is that why the signal out of the BNC when using the Bandpass Adjust function looks odd (different than Hans signal. I know his wasn't 80m but I don't remember the band)

Yep, the 80m rig. Winter Field Day is this weekend. I'm going to actually be a Ham operator instead of a repairman this weekend and have a little fun.

I may put the 80m rig in a box and work on one of the higher frequency QCX rigs. I have one for 30m built except I need to wind the toroids. I've had so much practice T1 should be easy.?

--
73
NE5U

Mike

Re: r33 36k resistor

#21151

Hi Bill,

? ?? Since Radio Shack closed their doors I have found that Amazon has resistor kits for sale at very reasonable prices, all different values, just something to look at.

73 John K2IZ

Re: My QCX40 problem and Han’s new troubleshooting guide

#21150

and I'm not to that point yet. At this point I'm trying to understand why it's transmitting... or maybe betters stated, why it's emitting RF. The waveform at the BNC with the resistor parallel to R43 is nothing at all like yours. According to my SA it's a signal frequency. When in receive mode the signal frequency is stable at about 15dBm above the noise floor of the SA (-75dBm). When I turn on the Bandpass Adjust it's not stable.Mike,
Is this an 80m QCX?
If so you are just being tooo sensitive.
The very small signal you see is always present on a direct conversion receiver. Some leaks out.
I guess it's modulated when adjusting...

73 Alan G4ZFQ

Re: My QCX40 problem and Han’s new troubleshooting guide

#21149

On Fri, Jan 26, 2018 at 06:02 am, Michael Lloyd wrote:

According to my SA it's a signal frequency

:o/ I wish we could edit our posts...

SINGLE frequency...
?
--
73
NE5U

Mike

Re: My QCX40 problem and Han’s new troubleshooting guide

#21148

I looked through the transmit mod symptoms:

Some constructors, seemingly tending to be the higher frequency versions of the kit, have reported a PA instability that resulted in one or more of the following symptoms:

1) high current draw on transmit?
2) low or unstable power output?
3) dead MPS2907 (in first batch of 500 kits, which used MPS2907 for keying transistor Q6)

and I'm not to that point yet. At this point I'm trying to understand why it's transmitting... or maybe betters stated, why it's emitting RF. The waveform at the BNC with the resistor parallel to R43 is nothing at all like yours. According to my SA it's a signal frequency. When in receive mode the signal frequency is stable at about 15dBm above the noise floor of the SA (-75dBm). When I turn on the Bandpass Adjust it's not stable.

Peak at the BNC (50Ω termination) in receive

?
When I turn on the test signal it starts to dance a little

Any ideas?

https://youtu.be/Q7ap5G9BTIw
?
--
73
NE5U

Mike

Apache Case on Sale

#21147

All:

Harbor Freight has their small Apache chase on sale for the month of February. Inside dimensions are:

?? Length: 8-3/8"
??? Height: 3-3/4"
???? Width: 5-11/16"

The case is similar to a small Pelican case, water resistant, and very rugged. If you plan on taking your QCX on a trip, this case would be a viable home for it. If you get their flyer, the coupon is on p. 16. The price is reduced from $15 to $10.

Jack, W8TEE

Re: QCX fault-finding guide #qcx

#21146

Same here Don - followed the instructions and my QCX 40m worked perfectly first time!

My only suggestion for an improvement to the manual is in the area of winding toroids. Hans refers to left- or right-handed winding but then goes on to describe the fitting process of a right-handed wound T1 toroid with saying that fitting a left-handed toroid will be slightly different. However, on writing this I wonder if I made a mistake - my left-handed T1 was certainly different or maybe I just had it upside down...hmmmm!

I didn't realise that I wind toroids left-handed until I wound T1 (I am left-handed)!

Simon, G0FCU.

Show quoted text

On 26 January 2018 at 07:41, Don Baker <donaldbbaker@...> wrote:

I must have done something wrong. QCX 40m seems to work fine with no problems. Maybe I shouldn't have RTM. ?
Thanks Hans, nice kit, now needs a case.

Don? WB9STS

Re: My QCX40 problem and Han’s new troubleshooting guide

#21145

Thanks Hans. I misread the write up as replace or add the resistor. I'll add that and hopefully move forward from there.
--
73
NE5U

Mike

Re: QLG1 GPS Kit #qlg

#21144

Hi Jim

you can use a 7486, exclusive or to check the frequency. Put a LED and a resistor 220 ohm on the output

and connect your rubidium, 10 MHz, to one input and the GPS disiplined VFO, 10 MHz to the other input.

If the LED flash, you have a frequency difference. A steady off or steady on means no difference. If you

wait 10 sec, then it is better than 0.1 Hz, if you wait 100 sec, then it is better than 0,001 Hz, teoretical.

73, oz8pz, Stig?

2018-01-26 10:44 GMT+01:00 Greg <groush-reno@...>:

Show quoted text

Jim,

I suggest using the Si5351A VFO/SigGen.? It has the advantage over the ProgRock of having a display and rotary encoder adjustment.? It can also use a GPS 1 pps signal to control the frequency and drift of the on-board 27 MHz xtal.? Or it can be set up to use an external frequency reference, such as your Rubidium oscillator.

How accurate do you want your calibrations?? Hans' method for "disciplining" the Si5351A-based synthesizers with a GPS RX will get you within about 0.25 Hz, as I understand his description.? That would be .025 ppm at 10 MHz, or 2.5 x 10^-8.? This accuracy is quite sufficient for WSPR and related modes.? However, if you want to compete in the ARRL Frequency Measuring Test, that accuracy is marginal.? Hams are often reporting off-the-air measurements with 0.1 to 0.01 Hz accuracy.

You could borrow/buy a real GPS disciplined Xtal oscillator (GPSDO) (such as a Thunderbolt) and use your method of looking at the zero beat with a scope.? The issue with zero beating is knowing which way to make the adjustment.? You'd adjust the Rb oscillator for a flat line, if you have DC coupling, and time the rate the line moves from top-to-bottom-and-back-to-top (1 cycle).? If the time t were 1 sec. (1cycle/1sec = 1Hz), then accuracy (if at 10 MHz) would be? 1/(10 x 10^6 x t) or 10^-7.? If t were 100 sec., then accuracy would be 10^-9.

Using a good Time Interval Analyzer and a GPSDO, its quite possible to adjust your Rb oscillator to at least 10^-10 or, maybe, 10^-11 accuracy.

If you want to go to extremes with calibrating your Rb oscillator, check out? the "time nuts" at?.? Tons of good info.

73,
Greg? WA7IRW

Re: r33 36k resistor

#21143

Hi Bill

If you use a 39K it will change the shape of the CW filter response a bit. It would be better to use a 33K and 3.3K in series. Or 39K and 470K in parallel. I can send you a real 36K resistor but it's not really worth the wait.

73 Hans G0UPL

Show quoted text

On Fri, Jan 26, 2018 at 3:11 AM, <bill1973ham@...> wrote:

My 17m kit was short 1 36 k resistor and I do not have one in my junk box can I use a 39 k in its place?
I also have some extra resistors that were not used. I can ask some club members if they have one if I can not use the 39 k.
Thank you?
Bill N8WS

Re: My QCX40 problem and Han’s new troubleshooting guide

#21142

Hi Mike

The resistor mod on the backside of the board,? is always a good idea. The MOSFET was not at fault.?

73 Hans G0UPL

Show quoted text

On Fri, Jan 26, 2018 at 6:48 AM, Michael Lloyd <mikell@...> wrote:

DUDE! :)

Following your totally gnarly troubleshooting guide I put a 0805 270Ω resistor across R43 and started probing.?

I never did get a sine wave on the ground side of secondary 3 (KIDDING). I touched up the leads on Secondary 3 because resistance was 0.7Ω and. It came down a little but still not to the level of shorted leads. With the shorting resistor in place, before I touched up the leads, C1 would (finally) adjust the output. Once I touched up the leads on T1 S3 the output pegged on 10. Hmmm... methinks there was a problem there.

Waveform at T1 S3. I didn't check before I touched up the leads. I should have

Final Pad LPF 3

There is a disturbance in The Force on the output of the BNC. I believe this is a subspace carrier... Ok not really but something is amiss.

I never really got an answer?about the transmit mod. I upgraded Q5 to the newer type MOSFET that comes in later kits.
Do I still need to add the resistor on?the backside of the board or was the MOSFET the culprit?

--
73
NE5U

Mike

Re: QLG1 GPS Kit #qlg

#21141

Jim,

I suggest using the Si5351A VFO/SigGen.? It has the advantage over the ProgRock of having a display and rotary encoder adjustment.? It can also use a GPS 1 pps signal to control the frequency and drift of the on-board 27 MHz xtal.? Or it can be set up to use an external frequency reference, such as your Rubidium oscillator.

How accurate do you want your calibrations?? Hans' method for "disciplining" the Si5351A-based synthesizers with a GPS RX will get you within about 0.25 Hz, as I understand his description.? That would be .025 ppm at 10 MHz, or 2.5 x 10^-8.? This accuracy is quite sufficient for WSPR and related modes.? However, if you want to compete in the ARRL Frequency Measuring Test, that accuracy is marginal.? Hams are often reporting off-the-air measurements with 0.1 to 0.01 Hz accuracy.

You could borrow/buy a real GPS disciplined Xtal oscillator (GPSDO) (such as a Thunderbolt) and use your method of looking at the zero beat with a scope.? The issue with zero beating is knowing which way to make the adjustment.? You'd adjust the Rb oscillator for a flat line, if you have DC coupling, and time the rate the line moves from top-to-bottom-and-back-to-top (1 cycle).? If the time t were 1 sec. (1cycle/1sec = 1Hz), then accuracy (if at 10 MHz) would be? 1/(10 x 10^6 x t) or 10^-7.? If t were 100 sec., then accuracy would be 10^-9.

Using a good Time Interval Analyzer and a GPSDO, its quite possible to adjust your Rb oscillator to at least 10^-10 or, maybe, 10^-11 accuracy.

If you want to go to extremes with calibrating your Rb oscillator, check out? the "time nuts" at?.? Tons of good info.

73,
Greg? WA7IRW

Re: QCX fault-finding guide #qcx

#21140

I must have done something wrong. QCX 40m seems to work fine with no problems. Maybe I shouldn't have RTM. ?

Thanks Hans, nice kit, now needs a case.

Don? WB9STS

Show quoted text

On Jan 25, 2018 10:02 AM, "Hans Summers" <hans.summers@...> wrote:

Hi all

I have written an extensive trouble-shooting guide for the QCX, describing how to signal trace through the receive and the transmit paths. To date I have a 100% success rate using this methodical approach to trace through and find errors.?

See?

I do not believe that assuming components are broken and replacing them is a good tactic. I think it is necessary to really understand the circuit and properly evaluate any other possibilities, before finally concluding a component has blown and needs replacement. Replacing components can be tricky and can incur the risk of causing additional problems. So it's a last resort!

I think that the exercise is also valuable to anyone who has a perfectly working QCX, because it will help you to understand your QCX more deeply (and love it more deeply too)... it is a very educational process. Even for me, who designed it :-)

I have written this as a web page, rather than including it in the manual, for two reasons:

1) Hopefully most people who follow the manual will have a working QCX which doesn't need fault-finding and?

2) I intend to update this trouble-shooting guide as and when new types of failures or new tricks for diagnosing failures become apparent.?

73 Hans G0UPL

r33 36k resistor

#21139

My 17m kit was short 1 36 k resistor and I do not have one in my junk box can I use a 39 k in its place?
I also have some extra resistors that were not used. I can ask some club members if they have one if I can not use the 39 k.
Thank you?
Bill N8WS

Re: My QCX40 problem and Han’s new troubleshooting guide

#21138

DUDE! :)

Following your totally gnarly troubleshooting guide I put a 0805 270Ω resistor across R43 and started probing.?

I never did get a sine wave on the ground side of secondary 3 (KIDDING). I touched up the leads on Secondary 3 because resistance was 0.7Ω and. It came down a little but still not to the level of shorted leads. With the shorting resistor in place, before I touched up the leads, C1 would (finally) adjust the output. Once I touched up the leads on T1 S3 the output pegged on 10. Hmmm... methinks there was a problem there.

Waveform at T1 S3. I didn't check before I touched up the leads. I should have

Final Pad LPF 3

There is a disturbance in The Force on the output of the BNC. I believe this is a subspace carrier... Ok not really but something is amiss.

I never really got an answer?about the transmit mod. I upgraded Q5 to the newer type MOSFET that comes in later kits.
Do I still need to add the resistor on?the backside of the board or was the MOSFET the culprit?

--
73
NE5U

Mike