Re: QMX+ No transmit or receive
Okay. I have finally experienced some real progress! I went poking around Q513 and Q515 and noticed that on the bases, i had continuity to ground at a rate of about 30 to 40 ohms. Lol, i don't?think that's correct. Collectors yes but bases NO. I checked C505 for a possible short and found a tiny, almost un-recognizeable?flake of solder. I Q-tipped it off? and used a small amount of rubbing alcohol in that area and BOOM! I have wattage now that was not there before. I am going to do some more sweeps and get back to the group.?
VY2KW
I have also noticed that DAC also originates from pin 29 of what i believe?is?IC203. Does this possibly mean that the I.C. may be defective? The pins are SOOOO small and i would rather not probe if i can help it. I have scanned the area with the jewellers loupe again but no solder whiskers.
On Sun, Dec 29, 2024 at 12:09?PM Joel Macneill via <joelmacneill1977= [email protected]> wrote: I am starting troubleshooting and this is where i have gotten so far.....During RECEIVE ...Gate of Q507 10.7v , source 12.0 v , DAC connection (base of Q513 i am pretty sure), is 0.06v, emitter of Q513 has.6v and collector is 0v. I will include a couple pics to make sureIi am on the correct FET. I have included 5 pics. First two are the gate and source of Q507 and the latter 3 are Base, collector and emitter (hopefully in that order) of Q513. I will continue on with troubleshooting however and try to get more info.
No problem Nic, I know sometimes it's hard to keep track of things.
?
Like you said there is a detailed description for the PA voltage regulator in the 5 W PA manual.
To make it short for the QMX - Q512 ... Q515, Q507 and some parts around are acting as an regulator. The voltage at B of Q515 should be equal to voltage at B of Q513. B of Q513 is connected to DAC. Voltage at B of Q515 is produced from the PA voltage by a voltage devider (coefficient is 0.16). So PA voltage should be 6.24 * voltage ADC. But there is a limitation. When voltage ADC is reaching 0.16 * max available voltage the PA voltage couldn't go higher.
?
Joel, your PA voltage is near 0 V. If the ADC voltage is significant higher than 0 V the PA voltage should be much higher. But why not, why doesn't the regulator act? I would check this:
- Are there solder blobs or tin whiskers affecting the regulator circuits? Are there elements not solderd well?
- How much voltage at ADC when PA voltage should be high?
- If voltage ADC is significant higher than 0 V check voltages at E, B and C of Q514 and show us all the values. How much supply current and voltage in this state? Is your power supply current limited? If yes to which value?
To make it simple, use RX mode. Check Menu - System config - Advanced config! - Mod. High in RX - ENABLED (default setting). This will switch on PA voltage during RX mode. Be aware in this state voltage ADC is higher than for linear regulation. Voltage at C of Q514 should be only a few volts - pulling voltage at G of Q507 3 V or more below "+12V".
?
73 Ludwig
?
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Re: U3S & 10W HF Amp Combo on 160m!
Al, coming back to thoughts of doing a 160m WSPR beacon of my own, wondering if I can learn a bit about the oddities of 160m propagation....
How do you trigger the amp on TX? RF Sensing circuit? Or is there some sort of PTT from the U3S?
?
-Nate?
N8BTR
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Clue number 36 in the series.
?
As mentioned before, the QCX-Mini has no issue. Only when I use the QCX+ does this happen.
?
Now, I have discovered completely by accident, that if I place my QRPguys tuner between the amp and the QCX+, and tune it for best SWR, the issue does not present itself. By the way, swapping in the Mini does not change the tuning of the tuner.
?
This is so weird.
--
regards,
Bryan, N0LUF
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Re: QMX+ No transmit or receive
I have also noticed that DAC also originates from pin 29 of what i believe?is?IC203. Does this possibly mean that the I.C. may be defective? The pins are SOOOO small and i would rather not probe if i can help it. I have scanned the area with the jewellers loupe again but no solder whiskers.
On Sun, Dec 29, 2024 at 12:09?PM Joel Macneill via <joelmacneill1977= [email protected]> wrote: I am starting troubleshooting and this is where i have gotten so far.....During RECEIVE ...Gate of Q507 10.7v , source 12.0 v , DAC connection (base of Q513 i am pretty sure), is 0.06v, emitter of Q513 has.6v and collector is 0v. I will include a couple pics to make sureIi am on the correct FET. I have included 5 pics. First two are the gate and source of Q507 and the latter 3 are Base, collector and emitter (hopefully in that order) of Q513. I will continue on with troubleshooting however and try to get more info.
No problem Nic, I know sometimes it's hard to keep track of things.
?
Like you said there is a detailed description for the PA voltage regulator in the 5 W PA manual.
To make it short for the QMX - Q512 ... Q515, Q507 and some parts around are acting as an regulator. The voltage at B of Q515 should be equal to voltage at B of Q513. B of Q513 is connected to DAC. Voltage at B of Q515 is produced from the PA voltage by a voltage devider (coefficient is 0.16). So PA voltage should be 6.24 * voltage ADC. But there is a limitation. When voltage ADC is reaching 0.16 * max available voltage the PA voltage couldn't go higher.
?
Joel, your PA voltage is near 0 V. If the ADC voltage is significant higher than 0 V the PA voltage should be much higher. But why not, why doesn't the regulator act? I would check this:
- Are there solder blobs or tin whiskers affecting the regulator circuits? Are there elements not solderd well?
- How much voltage at ADC when PA voltage should be high?
- If voltage ADC is significant higher than 0 V check voltages at E, B and C of Q514 and show us all the values. How much supply current and voltage in this state? Is your power supply current limited? If yes to which value?
To make it simple, use RX mode. Check Menu - System config - Advanced config! - Mod. High in RX - ENABLED (default setting). This will switch on PA voltage during RX mode. Be aware in this state voltage ADC is higher than for linear regulation. Voltage at C of Q514 should be only a few volts - pulling voltage at G of Q507 3 V or more below "+12V".
?
73 Ludwig
?
|
Re: QMX+ No transmit or receive
I am starting troubleshooting and this is where i have gotten so far.....During RECEIVE ...Gate of Q507 10.7v , source 12.0 v , DAC connection (base of Q513 i am pretty sure), is 0.06v, emitter of Q513 has.6v and collector is 0v. I will include a couple pics to make sureIi am on the correct FET. I have included 5 pics. First two are the gate and source of Q507 and the latter 3 are Base, collector and emitter (hopefully in that order) of Q513. I will continue on with troubleshooting however and try to get more info.
No problem Nic, I know sometimes it's hard to keep track of things.
?
Like you said there is a detailed description for the PA voltage regulator in the 5 W PA manual.
To make it short for the QMX - Q512 ... Q515, Q507 and some parts around are acting as an regulator. The voltage at B of Q515 should be equal to voltage at B of Q513. B of Q513 is connected to DAC. Voltage at B of Q515 is produced from the PA voltage by a voltage devider (coefficient is 0.16). So PA voltage should be 6.24 * voltage ADC. But there is a limitation. When voltage ADC is reaching 0.16 * max available voltage the PA voltage couldn't go higher.
?
Joel, your PA voltage is near 0 V. If the ADC voltage is significant higher than 0 V the PA voltage should be much higher. But why not, why doesn't the regulator act? I would check this:
- Are there solder blobs or tin whiskers affecting the regulator circuits? Are there elements not solderd well?
- How much voltage at ADC when PA voltage should be high?
- If voltage ADC is significant higher than 0 V check voltages at E, B and C of Q514 and show us all the values. How much supply current and voltage in this state? Is your power supply current limited? If yes to which value?
To make it simple, use RX mode. Check Menu - System config - Advanced config! - Mod. High in RX - ENABLED (default setting). This will switch on PA voltage during RX mode. Be aware in this state voltage ADC is higher than for linear regulation. Voltage at C of Q514 should be only a few volts - pulling voltage at G of Q507 3 V or more below "+12V".
?
73 Ludwig
?
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Re: A question about L401 windings QMX v1 vs QMX v2
Thanks Chris--I really dont know, but since it is now mounted as detailed in the rev2 instructions, --albeit on a rev1 board,? ?I am going to leave as is. Once my pwr supply boards arrive, and if i am able to bring it back to life, I will try it out first. If needed I can change down the road. Following the whole L401 saga is quite a read and it takes a lot of attention to follow the whole story.
?
Even the photographs had me scratching my head as it appeared the wires would come over the top at the tapped areas which was physicially impossible to do, but appeared that way in the photo. The top down photos are very clear but without a bit of angle they lack the perspective to tell whats going on...minor issues in the big scheme of things. I am enjoying every aspect of this little rig--even the troubleshooting. HNY.
?
Scott vy1co
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Re: Release of version 1.2 of ABS solution for QMX+ (Automatic internal antenna tuner, internal battery and internal speaker with audio amp)
#ABS
#ATU
#PSU
#QMXplus
How does one sign up in a group buy.
?
Thanks, Dave
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The power dropping in half sure sounds like a bad solder joint on one side of the push pull. Always suspect in a kit.?
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Show quoted text
On Dec 29, 2024, at 13:39, Greg McCain via groups.io <gamccain50@...> wrote:
?May not apply in your setup but ... Once when using a 50W amp with my QMX HB, the Q was dropping TX. Traced it down to an older, failing BNC interconnect cable that I was using.?
Wasn't open, but was showing SWR readings all over the place, intermittently.
Replaced it. All good. Older cable now in a landfill.
Gave up trying to repair flaky cables years ago. Just not worth the grief, especially in a production data center environment. That included some really expensive 50 pin beasts for connecting peripherals to mainframes and long run DB-25 pin serial comm cables.?
And for those who might be interested .... I recently chucked a batch of Amazon sourced, likely Chinese, BNC T connectors. Hadn't noticed that they were 'wiggly' in the leg that connected to the Qs. Replaced them with Amphenol brand ones I ordered from Mouser. Rock solid!
Greg On Sun, Dec 29, 2024 at 1:07 PM, Bryan Curl via groups.io <bc3910@...> wrote: Sorry Bruce, I appreciate your help as well and dint mean to call you Evan, not that that was an insult by any means HI HI
?
Okay, so... PTT voltage measured at R14 is about 4v and remains very close on power drop.
The Supply to R5 measured at R5 is 3.5v and also remains very close on power drop.
?
In a new experiment, the plot thickens... I dug out the qcx-mini. Viola, this radio does not exhibit this problem with the amp.? And the amp gets a ton warmer considerably faster.
?
So, now thinking the amp is okay and the issue is with the QCX+ But what confuses me is that the QCX+ by itself behaves normally. Only when connected to the amp do I see the issue.
?
?
regards,
Bryan, N0LUF
|
May not apply in your setup but ... Once when using a 50W amp with my QMX HB, the Q was dropping TX. Traced it down to an older, failing BNC interconnect cable that I was using.?
Wasn't open, but was showing SWR readings all over the place, intermittently.
Replaced it. All good. Older cable now in a landfill.
Gave up trying to repair flaky cables years ago. Just not worth the grief, especially in a production data center environment. That included some really expensive 50 pin beasts for connecting peripherals to mainframes and long run DB-25 pin serial comm cables.?
And for those who might be interested .... I recently chucked a batch of Amazon sourced, likely Chinese, BNC T connectors. Hadn't noticed that they were 'wiggly' in the leg that connected to the Qs. Replaced them with Amphenol brand ones I ordered from Mouser. Rock solid!
On Sun, Dec 29, 2024 at 1:07 PM, Bryan Curl via groups.io <bc3910@...> wrote: Sorry Bruce, I appreciate your help as well and dint mean to call you Evan, not that that was an insult by any means HI HI
?
Okay, so... PTT voltage measured at R14 is about 4v and remains very close on power drop.
The Supply to R5 measured at R5 is 3.5v and also remains very close on power drop.
?
In a new experiment, the plot thickens... I dug out the qcx-mini. Viola, this radio does not exhibit this problem with the amp.? And the amp gets a ton warmer considerably faster.
?
So, now thinking the amp is okay and the issue is with the QCX+ But what confuses me is that the QCX+ by itself behaves normally. Only when connected to the amp do I see the issue.
?
?
regards,
Bryan, N0LUF
|
Re: WSJT-X on Raspberry PI 3B and QMX+ unstable
I obtained and tried a few good well-shielded and ferrite-beaded USB-C cables but the situation has not improved. The combination works after several resetting and restarting but then suddenly tx no more though rx keeps working. I tried Windows 10 version of WSJT-X as well as MacBook version, but the combinations behave in the same manner. It works a while then tx stops.
?
Any idea?
?
Hiroki AH6CY?
|
Sorry Bruce, I appreciate your help as well and dint mean to call you Evan, not that that was an insult by any means HI HI
?
Okay, so... PTT voltage measured at R14 is about 4v and remains very close on power drop.
The Supply to R5 measured at R5 is 3.5v and also remains very close on power drop.
?
In a new experiment, the plot thickens... I dug out the qcx-mini. Viola, this radio does not exhibit this problem with the amp.? And the amp gets a ton warmer considerably faster.
?
So, now thinking the amp is okay and the issue is with the QCX+ But what confuses me is that the QCX+ by itself behaves normally. Only when connected to the amp do I see the issue.
?
?
regards,
Bryan, N0LUF
|
Re: Fab shop board assembly
Odd how things work. I posted a link here to this exact video a few hours before you. It's titled the Magic of Making PCBs ...? Did you see my post and get a subconscious idea to look up the topic?? The odds of us both posting on the same, rather exotic topic at the same time, are remote.?
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Re: QMX+ receiver clipping distortion on 40M CW during RAC contest...
Hi Dan, That sounds more likely to me than that the receiver was being crunched by all the signals. If I switch to the digi mode, the clipping sounds on the CW signals go away entirely... but the amplitude also drops to a small fraction of when CW mode. The AGC settings are currently the factory default settings. Being a DSP rig, I presume that the AGC is purely an audio function? -Chuck Harris - WA3UQV On Sun, 29 Dec 2024 09:19:58 -0800 "Daniel Conklin via groups.io" <danconklin2@...> wrote: Chuck,
It's likely the combination of the filter you were using and your AGC
settings was causing the middle amplitude ro be pulled in two or more
directions. You might play with the AGC settings under busy
conditions to start with, and work from there. I often just turn the
AGC off. -- 73, Dan - W2DLC
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I found this interesting.? I vaguely understood how pcb's are manufactured, but had even less idea how all the smt parts were put on & tested...
?
Search YouTube for "Inside a PCB soldering factory"
( I don't provide links for security reasons)
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Re: QMX+ receiver clipping distortion on 40M CW during RAC contest...
Chuck,
It's likely the combination of the filter you were using and your AGC settings was causing the middle amplitude ro be pulled in two or more directions. You might play with the AGC settings under busy conditions to start with, and work from there. I often just turn the AGC off.
--
73, Dan - W2DLC
|
Re: QMX+ No transmit or receive
No problem Nic, I know sometimes it's hard to keep track of things.
?
Like you said there is a detailed description for the PA voltage regulator in the 5 W PA manual.
To make it short for the QMX - Q512 ... Q515, Q507 and some parts around are acting as an regulator. The voltage at B of Q515 should be equal to voltage at B of Q513. B of Q513 is connected to DAC. Voltage at B of Q515 is produced from the PA voltage by a voltage devider (coefficient is 0.16). So PA voltage should be 6.24 * voltage ADC. But there is a limitation. When voltage ADC is reaching 0.16 * max available voltage the PA voltage couldn't go higher.
?
Joel, your PA voltage is near 0 V. If the ADC voltage is significant higher than 0 V the PA voltage should be much higher. But why not, why doesn't the regulator act? I would check this:
- Are there solder blobs or tin whiskers affecting the regulator circuits? Are there elements not solderd well?
- How much voltage at ADC when PA voltage should be high?
- If voltage ADC is significant higher than 0 V check voltages at E, B and C of Q514 and show us all the values. How much supply current and voltage in this state? Is your power supply current limited? If yes to which value?
To make it simple, use RX mode. Check Menu - System config - Advanced config! - Mod. High in RX - ENABLED (default setting). This will switch on PA voltage during RX mode. Be aware in this state voltage ADC is higher than for linear regulation. Voltage at C of Q514 should be only a few volts - pulling voltage at G of Q507 3 V or more below "+12V".
?
73 Ludwig
?
|
? on the insulators
Agree you still have a thermal-linked problem of some sort.?
As you have a repeatable test routine Capture some figures for the bias voltage source (regulator output ) as this goes on and also the PTT system?
(Q3 and Q6 drains)
|
Re: QMX+ receiver clipping distortion on 40M CW during RAC contest...
Hi Ed, Indeed, contests can be trying, but there wasn't a hot signal on the band using my little tossed out the window wire antenna. My little Oak Hills Research QRP 40M rig, with a DBM, was similarly priced to the QMX+. I didn't try it that night, but in the past it has been unfazed by much heavier contesting activity, such as Field Day... Are others finding the QMX+ receiver to be that weak? -Chuck Harris - WA3UQV On Sun, 29 Dec 2024 11:05:30 -0500 "Ed Kwik via groups.io" <ekwik@...> wrote: Chuck,
A crowed contest environment can challenge any transceiver’s
receiver. The transceivers that are designed to perform well in
contests can cost many thousand of dollars. The QMX+ is an
outstanding bang-for-the-buck rig but it does have it’s limitations.
Ed AB8DF
On Dec 29, 2024, at 10:46 AM, Chuck Harris via groups.io
<cfharris@...> wrote:
Hi,
I have been playing with my QMX+ over the last month
or so since I built it, and it has been behaving quite
nicely. Mostly, I have been listening in on W1AW's
high speed CW, hoping to one day have enough confidence
to actually do my first CW QSO since being licensed a
half century ago. W1AW rolls in here very strong.
Anyway, the Canadians were having their RAC contest
over the weekend, so I thought that I would listen in,
and brush up on my experience with contest exchanges.
In the beginning, all was well, but as the contest
built up steam, and there was a forest of CW signals on
the air, I noticed a peculiar thing: The low level
signals all had a raspy random noise signature riding
on top of their CW tones. If a signal was strong
enough to activate the AGC, the noise went away, but for
any signal below the AGC threshold, the noise was there,
no matter where I was tuned relative to the carrier.
At first, I thought the contestants were using poor
quality rigs with bad CW signals... but after the number
of such noisy CW signals reached the dozens, I had to
turn my pointy finger back in my direction.
It has to be my QMX+.
So, this morning, I investigated the QMX+'s low level
signal behavior using a signal generator, to see if I
could duplicate the issue. I couldn't.
The tone was sweet and pure all the way from S9++ down
until it became inaudible.
It would seem that it has something to do with large
numbers of middling strength signals within the
receiver's band.
Note that the noisy signals weren't on the threshold of
disappearing gracefully into the noise. The signals were
all head and shoulders above the background noise. Their
tone sounded like it was being clipped, like a guitar run
through fuzzbox. They would be easy copy if the tone was
clean.
So, to capsulize,
Only a few strong, or weak signals: clean and pure tone.
Lots of middling signals, crackly/clipping noise on top of
the CW tones.
Ideas?
-Chuck Harris - WA3UQV
|
Scott... Although I have not received my QMX yet, I was planning on running it with a 3Ah 9v bioenno battery to start with.? I have some LM2596 DC-DC buck converter's which I'd purchased for another project and at some point plan on using one with a 12v talentcell 3Ah rechargable, hoping the buck converter is quiet.
?
Rich, AD?SN
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Re: QMX+ receiver clipping distortion on 40M CW during RAC contest...
Chuck,
A crowed contest environment can challenge any transceiver’s receiver. The transceivers that are designed to perform well in contests can cost many thousand of dollars. The QMX+ is an outstanding bang-for-the-buck rig but it does have it’s limitations.
Ed
AB8DF
toggle quoted message
Show quoted text
On Dec 29, 2024, at 10:46 AM, Chuck Harris via groups.io <cfharris@...> wrote:
Hi,
I have been playing with my QMX+ over the last month
or so since I built it, and it has been behaving quite
nicely. Mostly, I have been listening in on W1AW's
high speed CW, hoping to one day have enough confidence
to actually do my first CW QSO since being licensed a
half century ago. W1AW rolls in here very strong.
Anyway, the Canadians were having their RAC contest
over the weekend, so I thought that I would listen in,
and brush up on my experience with contest exchanges.
In the beginning, all was well, but as the contest
built up steam, and there was a forest of CW signals on
the air, I noticed a peculiar thing: The low level
signals all had a raspy random noise signature riding
on top of their CW tones. If a signal was strong
enough to activate the AGC, the noise went away, but for
any signal below the AGC threshold, the noise was there,
no matter where I was tuned relative to the carrier.
At first, I thought the contestants were using poor
quality rigs with bad CW signals... but after the number
of such noisy CW signals reached the dozens, I had to
turn my pointy finger back in my direction.
It has to be my QMX+.
So, this morning, I investigated the QMX+'s low level
signal behavior using a signal generator, to see if I
could duplicate the issue. I couldn't.
The tone was sweet and pure all the way from S9++ down
until it became inaudible.
It would seem that it has something to do with large
numbers of middling strength signals within the
receiver's band.
Note that the noisy signals weren't on the threshold of
disappearing gracefully into the noise. The signals were
all head and shoulders above the background noise. Their
tone sounded like it was being clipped, like a guitar run
through fuzzbox. They would be easy copy if the tone was
clean.
So, to capsulize,
Only a few strong, or weak signals: clean and pure tone.
Lots of middling signals, crackly/clipping noise on top of
the CW tones.
Ideas?
-Chuck Harris - WA3UQV
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Tom Clifton
Daniel Conklin
Bruce Akhurst
rsmith