Re: Still digging... looking for a low audio issue
#problem
#qcx
So last night I went and tested all the resistor values in the last 2 stages. All are OK. I have tested continuity tests on all traces, all ok. Not exactly sure how I can test for a leaky Q7 with out pulling the device. I do have replacements on the way.?
Thanks all for for the suggestions.
I have parts arriving this week. I¡¯m going to take a break mull things over in my head anger back to it later.
73;
Kurt
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Re: QSX Enclosure Request
I built my 6/4/2m and 5W PA module rig in a reclaimed plastic battery casing, nice shade of yellow, convenient carrying handle, etc. No screening, no TVI, works fine.
73 Ken G4APB
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Re: 30m QCX working ¨C but not for long....
Hi Glen
On transmit the decode input signal is obtained from the key. Not from the 700Hz tone. There is no need to go through the whole detection stage, with amplitude variation tracking etc., when the keying state is already known...?
If the iambic keyer mode is being used, the decoder also skips the stage which tracks keying speed variations, since the keying speed is already known.?
73 Hans G0UPL
On Sat, Sep 22, 2018 at 11:49 PM Glen Leinweber < leinwebe@...> wrote: I have made a guess regarding QCX Morse decoding.....
Am guessing that Hans does receiver decoding and transmitter decoding the same way:
Audio is picked off at IC10B pin 7 and goes into analog-to-digital converter IC2 pin23.
From there, it is digitally processed in a 700 Hz bandpass filter, and its amplitude detected.
Am guessing that if transmit 700 Hz sidetone is Morse-decoded, then audio is present at IC10B
output - this is very near the receiver's output.
I may be wrong: Hans may have pumped the key signal into the Morse decoder, and
in that case, audio digital signal would be ignored.
If my guess is right, then that leaves one stage to troubleshoot: IC10A
Alan's troubleshooting suggestions (added below)? are right-on. Those 10V measurements on
IC10B seem high. A resistor value wrong? Those 10K resistors look similar to 1K resistors.
---------------------
Alan G4ZFQ wrote:
Are you looking at the manual? These voltages do not match. IC10 pin 5 should be fixed by a potential divider, something around 6V if measured with a DVM, Hans measured 4.2 with the inbuilt meter.
Check R39, 40 and joints around here.
°Ú¡±Õ
About Q7:
Shows it is not actually turned on. I'd expect the drain to be 0V. Have you checked the resistance to ground here? And you are positive C21, 22 are the right way round?
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Re: 30m QCX working ¨C but not for long....
I have made a guess regarding QCX Morse decoding.....
Am guessing that Hans does receiver decoding and transmitter decoding the same way:
Audio is picked off at IC10B pin 7 and goes into analog-to-digital converter IC2 pin23.
From there, it is digitally processed in a 700 Hz bandpass filter, and its amplitude detected.
Am guessing that if transmit 700 Hz sidetone is Morse-decoded, then audio is present at IC10B
output - this is very near the receiver's output.
I may be wrong: Hans may have pumped the key signal into the Morse decoder, and
in that case, audio digital signal would be ignored.
If my guess is right, then that leaves one stage to troubleshoot: IC10A
Alan's troubleshooting suggestions (added below)? are right-on. Those 10V measurements on
IC10B seem high. A resistor value wrong? Those 10K resistors look similar to 1K resistors.
---------------------
Alan G4ZFQ wrote:
Are you looking at the manual? These voltages do not match. IC10 pin 5 should be fixed by a potential divider, something around 6V if measured with a DVM, Hans measured 4.2 with the inbuilt meter.
Check R39, 40 and joints around here.
°Ú¡±Õ
About Q7:
Shows it is not actually turned on. I'd expect the drain to be 0V. Have you checked the resistance to ground here? And you are positive C21, 22 are the right way round?
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Re: Still digging... looking for a low audio issue
#problem
#qcx
What DC voltages do you measure on pins 2&3 of IC9?? If they're close to expected (4.8v and 0.65v), then you have a wrong/bad part in that circuit or Q7 is leaky/shorted.? you should be able to measure the resistors in circuit (radio is off), and check the markings on the capacitors (222) C19 & 20 with a magnifying glass.? This stage is part of the audio bandpass filtering, and a wrong part will put the filter to something other than the desired 700 hz, giving low gain.
If you have a 'scope, you can rule out problems with Q7 by comparing IC9 pin 1 signal level with the volume set loud vs all the way down - it should stay the same as volume knob changes.? Hope this helps.
73 Paul K9ARF
On Saturday, September 22, 2018 2:55 PM, Alan de G1FXB via Groups.Io <g1fxb@...> wrote:
Hi Kurt,
before you warm up the Soldering Iron...
If the voltages around the op amp is correct, I would not condemn
the IC as faulty.
It's a DC coupled device, It would be strange for it to have the
correct DC conditions` but not pass AC (audio)
If troubleshooting with a wet finger from the earphone socket back
to the gain control proves inconclusive.
One of your troubleshooting tools you said you had was an amplified
speaker,
Have you tried tracing the audio from front to back in the other
direction?
(Some times it's more revealing to trace a signal rather than
injecting one.)
You can use the in-built RF generator to compare with your QCX's?
for comparison.
If it indicates IC9 again, then fair comment.
Alan
On 22/09/2018 16:16, Kurt Zimmerman
wrote:
Oddly voltages seem to compare about equal on both.
Kurt
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Re: Was :OLED screen for QCX Now: Thermal considerations for QCX
Charlie,
I fly radio controlled airplanes and use LiFeP04 batteries to power my receivers. They are great!
When fully charged each cell will be 3.7 volts; a 4S pack will be 14.8VDC.
Here is a pack that would run a transmitter for a long time.
A 30 C rated pack can produce 30 times 4.2 amps. Yes, the pack will get very warm and be drained rapidly, but for lighter
current loading, it will work great. It can be charged by a low priced hobby charger like one of the following:
I own both of these chargers and they work great. I charge at 1C rating. This (in theory) means it takes an hour to fully charge the battery.
For the battery URL listed above, I would set my charger to 4.2 amps and 4 cells and it will automatically stop charging when the pack is fully charged. WARNING: NEVER LEAVE CHARGING BATTERIES UNATTENDED! Flame proof 'sacks' are available to contain a charging battery.
If you keep them stored in a reasonably cool place, don't discharge them below the minimum cell value, and don't drop/damage them, you
can expect to get 300-500 cycles (probably years of service). When storing the batteries, always make sure you use the battery charger to charge or discharge the cells to the 'storage' voltage.
I have LiPo batteries that are 2 years old and still going strong. Some I fly daily. Others, weekly. So far, I have not had any issues.
Best Flying, Oh, correction Best DX! :)
Garry / WD0DUD
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-----Original Message----- From: g4sra via Groups.Io Sent: Saturday, September 22, 2018 11:52 AM To: [email protected]Subject: Re: [QRPLabs] Was :OLED screen for QCX Now: Thermal considerations for QCX John, Thanks for the pointer. Unfamiliar with LiFePO4 so just carried out some quick research. An interesting technology, the safety aspect certainly appeals and so does the reduced weight. Battery charge management seems a little complex with each cell having its own controller, I wonder what the reliability is like. Prohibitively expensive here in the UK. 73 Charlie On 22/09/2018 19:07, John VA7JBE via Groups.Io wrote: If you're looking for a more stable battery chemistry without sacrificing (too much) energy density, then you might look into LiFePO4 (lithium iron phosphate) batteries. It's the kind of chemistry that's used in electric vehicle batteries because you can basically cut them in half while they're discharging and they won't even start smoking. The nominal voltage per cell (3.2v vs. 3.7v) is lower than lithium ion batteries, but a 4S configuration can act as a drop-in replacement for SLA batteries. In particular, you might look at cells manufactured by A123, or the batteries made by BioEnno ( ).
Cheers,
John VA7JBE
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Re: Was :OLED screen for QCX Now: Thermal considerations for QCX
Reliability? Rated 2000 recharges @ 90% discharge. That's why the individual cell charge controllers, so none of the cells get overcharged.
Jim
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On 09/22/2018 02:52 PM, g4sra via Groups.Io wrote: John,
Thanks for the pointer. Unfamiliar with LiFePO4 so just carried out some
quick research. An interesting technology, the safety aspect certainly
appeals and so does the reduced weight. Battery charge management seems
a little complex with each cell having its own controller, I wonder what
the reliability is like. Prohibitively expensive here in the UK.
73 Charlie
On 22/09/2018 19:07, John VA7JBE via Groups.Io wrote:
If you're looking for a more stable battery chemistry without sacrificing (too much) energy density, then you might look into LiFePO4 (lithium iron phosphate) batteries.? It's the kind of chemistry that's used in electric vehicle batteries because you can basically cut them in half while they're discharging and they won't even start smoking.? The nominal voltage per cell (3.2v vs. 3.7v) is lower than lithium ion batteries, but a 4S configuration can act as a drop-in replacement for SLA batteries.? In particular, you might look at cells manufactured by A123, or the batteries made by BioEnno ( ).
Cheers,
John VA7JBE
|
Re: Still digging... looking for a low audio issue
#problem
#qcx
Hi Kurt,
before you warm up the Soldering Iron...
If the voltages around the op amp is correct, I would not condemn
the IC as faulty.
It's a DC coupled device, It would be strange for it to have the
correct DC conditions` but not pass AC (audio)
If troubleshooting with a wet finger from the earphone socket back
to the gain control proves inconclusive.
One of your troubleshooting tools you said you had was an amplified
speaker,
Have you tried tracing the audio from front to back in the other
direction?
(Some times it's more revealing to trace a signal rather than
injecting one.)
You can use the in-built RF generator to compare with your QCX's?
for comparison.
If it indicates IC9 again, then fair comment.
Alan
On 22/09/2018 16:16, Kurt Zimmerman
wrote:
toggle quoted message
Show quoted text
Oddly voltages seem to compare about equal on both.
Kurt
|
Re: Was :OLED screen for QCX Now: Thermal considerations for QCX
John,
Thanks for the pointer. Unfamiliar with LiFePO4 so just carried out some
quick research. An interesting technology, the safety aspect certainly
appeals and so does the reduced weight. Battery charge management seems
a little complex with each cell having its own controller, I wonder what
the reliability is like. Prohibitively expensive here in the UK.
73 Charlie
toggle quoted message
Show quoted text
On 22/09/2018 19:07, John VA7JBE via Groups.Io wrote: If you're looking for a more stable battery chemistry without sacrificing (too much) energy density, then you might look into LiFePO4 (lithium iron phosphate) batteries.? It's the kind of chemistry that's used in electric vehicle batteries because you can basically cut them in half while they're discharging and they won't even start smoking.? The nominal voltage per cell (3.2v vs. 3.7v) is lower than lithium ion batteries, but a 4S configuration can act as a drop-in replacement for SLA batteries.? In particular, you might look at cells manufactured by A123, or the batteries made by BioEnno ( ).?
Cheers,
John VA7JBE
|
Re: Still digging... looking for a low audio issue
#problem
#qcx
Hello Paul,
Saturday, September 22, 2018
This is very true. If you build something and it works straight away
you tend to just use it. If it doesn't you curse but after you've
fixed it you have generally good idea of HOW it works :) The joy and
education of building, rather than black box purchasing.
Best regards,
Chris 2E0ILY mailto:chris@...
PB> Another possibility is a solder bridge or short between pins 2&3
PB> which would negate any gain of the stage.
PB> Otherwise I would check C19 & 20 and R34 & 35 first. It's easier
PB> to desolder a two pin component than an IC.
PB> I find I learn more by troubleshooting what I've built than anything.
PB> Good Luck
PB> K9ARF Paul
PB> On Saturday, September 22, 2018 12:04 PM, wb8yyy via Groups.Io
PB> <wb8yyy@...> wrote:
PB>
PB> Kurt
PB> if you hadn't thought of this,use the QCX built-in test source to
PB> inject a signal and your ears as the other end. I found a audio
PB> misconnection merely by touching every part. most of the rig is
PB> audio. if you built 3 of these rigs with only one issue - you are
PB> incredibly good - 3X better than me! enjoy the journey.
PB> Curt
PB> PS do acquire a good-enough scope if one comes your way - but you can do much without one.
PB>
--
Best regards, Chris Wilson (2E0ILY)
|
Re: Still digging... looking for a low audio issue
#problem
#qcx
Another possibility is a solder bridge or short between pins 2&3 which would negate any gain of the stage. Otherwise I would check C19 & 20 and R34 & 35 first.? It's easier to desolder a two pin component than an IC.
I find I learn more by troubleshooting what I've built than anything. Good Luck
K9ARF Paul
On Saturday, September 22, 2018 12:04 PM, wb8yyy via Groups.Io <wb8yyy@...> wrote:
Kurt
if you hadn't thought of this,use the QCX built-in test source to inject a signal and your ears as the other end.? I found a audio misconnection merely by? touching every part.? most of the rig is audio.? if you built 3 of these rigs with only one issue - you are incredibly good - 3X better than me!? enjoy the journey.?
Curt
PS do acquire a good-enough scope if one comes your way - but you can do much without one.?
|
Re: Was :OLED screen for QCX Now: Thermal considerations for QCX
If you're looking for a more stable battery chemistry without sacrificing (too much) energy density, then you might look into LiFePO4 (lithium iron phosphate) batteries.? It's the kind of chemistry that's used in electric vehicle batteries because you can basically cut them in half while they're discharging and they won't even start smoking.? The nominal voltage per cell (3.2v vs. 3.7v) is lower than lithium ion batteries, but a 4S configuration can act as a drop-in replacement for SLA batteries.? In particular, you might look at cells manufactured by A123, or the batteries made by .?
Cheers,
John VA7JBE
|
Re: QSX Enclosure Request
Yes the two standards for mil is OD and Desert.? Rare to see a radio with camo finish.
Spray cans are wonderful and I'd urge that for those worrying it.? Get an umbrella too.
IF its too hot for the radio likely? you need some protection and SPF60.
If your worried about EMP, get a nuke rated umbrella.? Grounding the case has little to do with RFI save?
for the wire can serve as a radiator.??
RFI and EMI are not the same thing and are generally easy to control but more of less not an issue
for an intentional? transmitter.
Allison
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Re: Still digging... looking for a low audio issue
#problem
#qcx
Kurt
if you hadn't thought of this,use the QCX built-in test source to inject a signal and your ears as the other end.? I found a audio misconnection merely by? touching every part.? most of the rig is audio.? if you built 3 of these rigs with only one issue - you are incredibly good - 3X better than me!? enjoy the journey.?
Curt
PS do acquire a good-enough scope if one comes your way - but you can do much without one.?
|
Re: Still digging... looking for a low audio issue
#problem
#qcx
Oddly voltages seem to compare about equal on both Kurt Between pins 7 and 2/3 are C19, 20 and R34. Where exactly does the signal stop? Can you inject a signal on pin 3? Even a sharp pin held in your hand may show something. IC9 might be faulty but you need to be sure. 73 Alan G4ZFQ
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Re: Still digging... looking for a low audio issue
#problem
#qcx
Oddly voltages seem to compare about equal on both.
Kurt
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Re: Still digging... looking for a low audio issue
#problem
#qcx
IC9 pin 7 is where I see the same signal on both rigs. However things are different on IC9 pin 3 & 1. On th /30 I see very little signal no where like my /40
73;
Kurt -W2MW?
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Re: QSX Enclosure Request
Seriously?
Paint the case if you don't like the color.? Military equipment is nearly always painted and it is usually some dark color.? Sitting there operating CW in direct sunlight is probably something best reserved for emergencies.? The first thing I am going to do, even before I hang the antenna, is look for some shade.
Regarding the "shielding" available in a metal enclosure;? I suppose there might be some shielding taking place but even the most trivial study of EMP will make it clear that any enclosure which is not nearly seamless will have limited value for shielding.? Surely there will be some shielding but unless you ground the case even that will be reduced.? It won't be RF transparent but it isn't going to cut down RFI nearly as much as one would expect.
Heat transference; for sure.? The voltage regulator on the little beastie needs a sink.? It works fine without one but runs hot.
It is a great little radio.
I've got an idea.? How about a removable hat of heavier grade aluminum foil, shiny side up and sized to wrap the sunny side of the cabinet?? A thin layer of insulation underneath the foil could increase the R value of the reflective hat.? Howard, n3fel.?
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Re: Still digging... looking for a low audio issue
#problem
#qcx
My guess at this point is a faulty IC9. Kurt, Where does your signal tracing end? On the pins of IC9? Have you checked the voltages on IC9? 73 Alan G4ZFQ
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Re: QSX Enclosure Request
I've got an idea.? How about a removable hat of heavier grade aluminum foil, shiny side up and sized to wrap the sunny side of the cabinet?? A thin layer of insulation underneath the foil could increase the R value of the reflective hat.? Howard, n3fel.?
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Kurt Zimmerman
James Daldry W4JED
Alan de G1FXB
