Re: #qmx QMX and waste heat from the finals
#qmx
Thanks, Cliff. I don't have any left over from my RPIs, but I found something on Amazon. I'm going to give that a try.
Wayne KB4DSF
On Wed, Aug 30, 2023 at 11:59?AM Cliff < ae5zaham@...> wrote: Wayne,
I had it lying around from a Raspberry Pi 3B that I had put in a different enclosure with different cooling so the heat sink wasn't needed anymore. Wish I had more of them.
Thanks, Cliff. You've been a tremendous help on this. Where did you find the heat sink you have on top of the finals?
Wayne KB4DSF
On Wed, Aug 30, 2023 at 11:41?AM Cliff < ae5zaham@...> wrote: Wayne,
There is just a hole through the plate to hold it in place and a foot that you can't see almost at the left hand edge under the plate the same as the one that is visible on the right hand side. It was made from a piece of aluminum molding that happened to have those two feet in the right place. I may try to put a piece of it under the finals on the QMX, but without the feet, as I'm sure there isn't enough room for the extra height of the feet.
I also added the diode across L14 so hopefully it will be as bullet proof as I can make it and baring operator "destructive" testing should last a long time.
Here's the reference from John Z to the diode "fix" in case you are interested.
The diode simply is in parallel with the 47uH inductor L14, with the
orientation shown in the photo provided by Paul W9AC. Cathode towards
the power supply connection, anode to the transformer center tap.
Any of the diodes he mentioned ?(1N4448, 1N4148, 1N914) will do a fine
job of absorbing the end-of-transmission voltage spike it produces.
I have used a 1N914.
/g/QRPLabs/message/105256
Hey, Cliff. How did you mount the plate under your finals?
Wayne KB4DSF
Wayne Greene
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Re: QMX - smoke - another C107/Q108 failure
Thanks Hans,
A friend of mine recovering from two strokes built the QMX before joining this group (showing all the issues) and it worked to his satisfaction. He is sending it to me as a gift as he doesn’t like digital modes. ?I have the kit I purchased from you (unbuilt yet) at Xenia and was just wondering…. I don’t turn things on and off quickly as that will cause more problems with computers than it’s worth but just had to ask.
Dave K8WPE since 1960 David J. Wilcox’s iPad
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On Aug 31, 2023, at 5:49 AM, Hans Summers <hans.summers@...> wrote:
? Hello Dave
I don't think that is necessary.?
With a lot of effort, messing around with a poor intermittent 12V power supply connection, while simultaneously holding the left knob (power on/off) pressed, I was able to kill the 5.6V zener. But I don't think it is a major risk. You really had to try hard, to do it. On Thu, Aug 31, 2023 at 12:43?PM David Wilcox K8WPE via <Djwilcox01= [email protected]> wrote: In this line of emails does it mean one should not turn the power ON and OFF in rapid succession or even semi quickly because it takes a few extra milliseconds for the power supply controls to do their job?? IE turn on, let it run a few seconds before turning off….. about the time needed to smell or see the magic smoke. ?
Dave K8WPE? David J. Wilcox’s iPad ? What a complete detailed response and education for everyone. I am impressed with your bandwidth and expertise relative to this wonderful QMX product.
Hi hi, bandwidth and expertise? You should ask my family, how often I showered, shaved, even SPOKE to them in the last few months! It's by far the biggest project I've ever done. So yeah I know every resistor and every line of code! I could probably write it all out from my head with very few errors!
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Re: QMX: Kit Build complete - My observations
Hi,
these are my first QMX HW test measurements.
73 Bojan S53DZ
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Re: QMX - smoke - another C107/Q108 failure
Hello Dave
I don't think that is necessary.?
With a lot of effort, messing around with a poor intermittent 12V power supply connection, while simultaneously holding the left knob (power on/off) pressed, I was able to kill the 5.6V zener. But I don't think it is a major risk. You really had to try hard, to do it.
On Thu, Aug 31, 2023 at 12:43?PM David Wilcox K8WPE via <Djwilcox01= [email protected]> wrote: In this line of emails does it mean one should not turn the power ON and OFF in rapid succession or even semi quickly because it takes a few extra milliseconds for the power supply controls to do their job?? IE turn on, let it run a few seconds before turning off….. about the time needed to smell or see the magic smoke. ?
Dave K8WPE? David J. Wilcox’s iPad ? What a complete detailed response and education for everyone. I am impressed with your bandwidth and expertise relative to this wonderful QMX product.
Hi hi, bandwidth and expertise? You should ask my family, how often I showered, shaved, even SPOKE to them in the last few months! It's by far the biggest project I've ever done. So yeah I know every resistor and every line of code! I could probably write it all out from my head with very few errors!
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Re: U3S No Power Troubleshooting
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Re: QMX - smoke - another C107/Q108 failure
In this line of emails does it mean one should not turn the power ON and OFF in rapid succession or even semi quickly because it takes a few extra milliseconds for the power supply controls to do their job? ?IE turn on, let it run a few seconds before turning off….. about the time needed to smell or see the magic smoke. ?
Dave K8WPE? David J. Wilcox’s iPad
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Show quoted text
On Aug 30, 2023, at 10:33 AM, Hans Summers <hans.summers@...> wrote:
? What a complete detailed response and education for everyone. I am impressed with your bandwidth and expertise relative to this wonderful QMX product.
Hi hi, bandwidth and expertise? You should ask my family, how often I showered, shaved, even SPOKE to them in the last few months! It's by far the biggest project I've ever done. So yeah I know every resistor and every line of code! I could probably write it all out from my head with very few errors!
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Re: U3S No Power Troubleshooting
?KI7MWA
This may help you troubleshoot
To measure? "rf"? I use this circuit and a common dc Volt meter (DVM)
At 10 mHz and 5 Volts and one BS170
Measure at output of C5 with filter removed
?? IF????? R5 is set to measure much over 1.5 V rms at C5 with filter removed?
THEN? one BS170 goes from warm to hot
P = (E^2) / R
(1.5 X 1.5) / 50? =? 0.045 W?? (45 mW)
72 73
John
N3AAZ
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Re: QDX - protection of BS17O PA
Hi Pierre,
my QDXs are built for +12V.
I am using these practices:
- added an antiparallel 1N4148 to L14,
- using a good +12V PS with a 1A current limit (and no higher voltage),
- matching the antenna before using QDX's TX.
73 Bojan S53DZ
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QDX - protection of BS17O PA
Finally what is the best solution to protect the BS170? Solder a 1N4448 or 4148 or 914 in parallel to L14? I read also 2 Zener diodes alongside T1? What should I chose?
73 - Pierre - FK8IH
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Re: QMX - sockets for BS170s
On Thu, Aug 31, 2023 at 12:52 AM, Reinhard Gr?nz wrote:
The QMX will not work without an adapted antenna.
How does it work with a resonant antenna that requires no tuner such as a dipole or K6ARK End Fed??? ? -- Compton VK2HRX Sydney, Australia
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Re: QMX - sockets for BS170s
Thank you all for your helpful input.??
Cliff - I'd be interested to hear how you get on, if you are inclined to let us know.
73
Chris? G4CWS
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Not sure how it will work but would the type C allow the clock to be set by connecting it to a phone/PC?
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Re: U3S No Power Troubleshooting
On 30/08/2023 22:04, KI7MWA via groups.io wrote: The QRP-Labs Dummy Load reports:
? 80 meters: 0.022 volts My guess is the BS170. Seems most likely (assuming the relays are switching.) Check for RF voltage at C5, input to LPFs. 73 Alan G4ZFQ
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Thanks Dan All noted, now on my list (the time setting one was there already).?
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Re: QMX - smoke - another C107/Q108 failure
I'm curious about what you propose, but that link doesn't show
anything. :-(
Paul -- AI7JR
On 8/30/23 18:17, Stephan Ahonen KE0WVA
wrote:
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>In the end, it has to be acknowledged that you can never
please all the people all the time, and have to try and strike a
balance somewhere. Which is often very difficult indeed.
I suppose you know your target market better than I do, and it's
presumptuous of me to think otherwise, I apologize.
>I think with my firmware changes I was able to very
substantially mitigate that vulnerability but the risk is still
there if extreme voltage fluctuations suddenly take place.
I think I remember reading somewhere that the control loop
operates at a frequency of 1 khz?
If this is the case then the software physically cannot respond
quickly enough. According to SPICE, if input voltage steps from 6
to 12 volts, with a 330u series inductor and 470u output
capacitor, 1 ms is enough time for the output voltage of the 5v
regulator to rise from 5v to 11v before the CPU even has an
opportunity to figure out that something is wrong.
to the power supply circuit would help. At a cost of
three extra parts (including a series resistor on the PWM_5V line,
not pictured), a voltage excursion now immediately shuts down PWM,
much faster than the CPU can react. Total BOM cost of $.10 or so?
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Re: QMX -- first try, first problems (bad sweeps, no output power)
Sorry folks - found the short - yes, it was at the BNC socket.
Steve
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Re: QMX - smoke - another C107/Q108 failure
>In the end, it has to be acknowledged that you can never please all the people all the time, and have to try and strike a balance somewhere. Which is often very difficult indeed.
I suppose you know your target market better than I do, and it's presumptuous of me to think otherwise, I apologize.
>I think with my firmware changes I was able to very substantially mitigate that vulnerability but the risk is still there if extreme voltage fluctuations suddenly take place.
I think I remember reading somewhere that the control loop operates at a frequency of 1 khz?
If this is the case then the software physically cannot respond quickly enough. According to SPICE, if input voltage steps from 6 to 12 volts, with a 330u series inductor and 470u output capacitor, 1 ms is enough time for the output voltage of the 5v regulator to rise from 5v to 11v before the CPU even has an opportunity to figure out that something is wrong.
to the power supply circuit would help. At a cost of three extra parts (including a series resistor on the PWM_5V line, not pictured), a voltage excursion now immediately shuts down PWM, much faster than the CPU can react. Total BOM cost of $.10 or so?
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Re: QMX won't power off and odd voltages on Q103
Phil,
You also mentioned that the tabs on the rotary encoder broke at one time and you installed wires to repair them. Please check that area for shorts to the rotary encoder housing and that the switch works correctly. Check at the 8 pin connector to make sure you are also checking continuity through the solder joints.
73 Kees K5BCQ
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Re: QMX -- first try, first problems (bad sweeps, no output power)
Hi Adam - I have the same symptoms as you - my rf sweeps are very similar with no receive or rf out. I've been stuck on this for hours - where was the short you fixed on yours? Did you mean the BNC socket?
I'm clutching at straws here!?
Many thanks,
Steve MW0KST
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David Wilcox K8WPE
Pierre - FK8IH
Compton
Paul - AI7JR