Solder pot for toroid leads
Does anyone use Solder pots for tinning and removing the enamel from the toroid leads? Any hints and tips?
I see a cheap one on Amazon for about $20. Any suggestions if I should buy special solder for this, or use my normal Kester 63/37 solder in it?
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Re: #qmx plus assembly one LP and Band filter at the time
#qmx
Yes, instales from the beguining and continuity test from the dummy load to the T507
73 azgael
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Finished my QMX+ build (9v), applied power - no smoke!
Put the latest firmware on and started playing.
Receiver works well, but when I run Diagnostics, the Bias SMPS shows fluctuating current (in red), and I get the pulsing noise in the headphones, and when monitoring RF on my SDR.
Following this and other post on the group I investigated further (visually - must be the 4th time I've gone over my solder joints with a jewellers loupe!)
On the reverse side of the board I checked Q516, and it has a split in it.
?
All other components look fine.
?
This makes at least three broken Q516s that I have seen reported in the group.
?
Hopefully the pictures appear and show the problem!
?
So I need to get hold of a new BC817 SMD and attempt to replace it.
?
It seems this is a possible problem in manufacturing? I don't think it is shipping or handling as the split is on the inside of the board (away from the edge).
?
Anymore cases of this?
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Does Hans monitor this group?
?
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R520 Wrong component value.
When testing my
newly built QMX+ I was getting high SWR readings while running the
diagnostics SWR test. Even when connected to a dummy load the
readings were around 2.7 to 1 across all bands. ?I removed and
re-wound T507 (twice) but could not resolve the problem. So I removed
T507 for a third time and started to check component values around
the bridge circuit. I found that R520, although marked as 68X (49.9 R)
, actually measured as 124.5 K.
Has anyone else seen
this problem.
Regards
Stephen
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Re: #qmx plus assembly one LP and Band filter at the time
#qmx
did you install the jumper at JP501 that connects T507 to the BNC?
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Re: #qmx plus assembly one LP and Band filter at the time
#qmx
Thank you Jerry?
I have checked l511 and l507 also rewind and solder t507 double check all continuity and inspect the solder all looks good but I still have the swr at 10 on 160m.?
from the diagnostic all voltages look good.?
I have no more ideas if someone has please share!?
thanks again?
73 azgael
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Re: New QMX+ Calibration victim
I've been wondering why some people regularly blow BS170s and the associated ICs while others don't.? Could it be how people are powering their devices?
?
If a user has a non current limited supply, such as a battery then a momentary glitch in the system , for example TX being active while CLK2 is not running while the DAC power is active, could cause high currents through one bank of the BS170s.? There's no inherent current limiting and it would not need excessive voltage.? It would only take a few milliseconds, that could make it difficult to spot.
?
People using current limited power supplies - limited to around an amp - could be largely immune to over current failures because the current limit would prevent them.
?
The power modulator seems to be derived from the one in the 5W HF PA kit, the difference is mainly that the PA kit has foldback current limiting and the QMX PA modulator doesn't.? Would having hardware PA current limiting help to preserve the output FETs?
?
?
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Re: 50 Watt Power Amplifier - Low Power, High Harmonics
#50w
#50wpa
There is an excellent stage by stage troubleshooting video on YouTube by a gentleman who uses the call sign NA5Y and that guidance got me this far. I can see gate signals like those in his video - but the waveforms at the drains of the transistors, and the waveform at the output of T3, don't resemble what he demonstrated.? The LPF filter is doing a good job of cleaning up the horrible harmonics visible at the output of T3, but in doing so I'm losing a lot of power.
?
I've never built an RF power amplifier before.? As others have commented, shotgun replacing of parts is hard on the printed circuit board, so before I load the parts cannon I hope to get some insight as to where these unwanted harmonics are coming from.
?
Bill
?
?
?
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Hi and thank you ... The radio was just finshed I powered up and tested buttons ect. Then I bumped the cw key to check rf power I whent back to recieve for 3 or 4 min. the screen brighted up then shutdown. Thats why I was thinking it was the power regulation. I been tracing the radio and if I got it right, I have the 3.3 volts that I think power up the cpu I have a voltage regulator and thinking of running the 3.3 volt to see if it power up however I not sure location of vdd I think the 3 volts power the cpu up and the cpu powers up the rest of the radio.?
I hope this helps? Joe?
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Re: 50 Watt Power Amplifier - Low Power, High Harmonics
#50w
#50wpa
Poor vision on my part, and san-serif fonts, make for poor legibility for me. .? The gentleman who reported 42 MHZ coming out of his test on a 20 metre amp was Kilo Zero India Kilo Romeo, Ben.? His post with photos was 51637 from August 2020. He finally decided that he had a bad component in his low-pass filter section.
?
Bill
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Nicely built.
It looks so spacious compared to the QMX+!
You might consider adding the AGC board.
?
73, Mike KK7ER
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From all of my readings of blown BS170;s I have to say that Hans was brilliant to have a built-in set of fuses by using the BS170. When your little rig stops working because of too much voltage or poor antennas you have a great chance of finding the destroyed part quickly.? Using a stronger more resilient component may very well exceed the capability of other components downstream that causes you more frustration?
Now buying bad, mislabeled or misrepresented replacement components makes the BS170 look even more like the real culprit for sure.? Leaving the search for alternative components for when the original component is no longer manufactured OR it is a KNOWN design fault for an overwhelming number of units seems the prudent thing to do.
Amazon, eBay and Floor Sweepers, Inc. are probably NOT your best source of quality components, exceptions noted.
Of course, just my opinion.
John KK4ITX
for Zephyrhills Area Amateur Radio Club Many of life's failures are people who did not realize how close they were to success when they gave up. ? ? ? ?Thomas A. Edison? ? ?
On Thursday, May 22, 2025 at 07:38:47 PM EDT, Eugene Pressley via groups.io <me.e2p2@...> wrote:
Are their any drawbacks to using the alternate mosfets? Anything that needs to be altered to use them??
?
Eugene,
?
You might want to also consider ordering some TN0110 FETs, a BS170 alternative, to have on hand if you decide you'd like to experiment with a hardier device.
I'd also suggest order a few 5ft. rolls of Solder Wick and a ChipQuik SMD removal kit.
?
73 de WD4AH
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I'm with Evan here.?
I'd never drill out a through-hole so I could insert a new diode.?
Nor would I use a push pin to try to (partially) clean out the hole.
Just clip the old diode or BS170 or whatever out and solder the new one to the stubs.
There is no need for the leads of the new part to go through the board.
?
Heating the board again and again to clean it with a solder sucker or solder wick is a fools errand.
The heat will compromise how well the pads adhere to the board.
If the pads get lifted off you then have?to figure out how to re-attach the broken traces.
Been there done that many times over a 45 yr career designing circuit boards.
?
The above is especially true for a multilayer board with internal traces and planes like the QMX.
A drill could easily cause shorts between internal layers near the hole.
Some parts such as BGA's (not found on the QMX) have pins (or balls) underneath the part,
and a single broken traces means throwing away a high value board since it can't be repaired
with a wire across the surface.? When dealing with RF or high speed clocks,? a patch wire
across the surface can behave much differently than the engineered trace through the board.
?
ChipQuik would work well enough when removing connectors and switches that must be
replaced with correct physical alignment,? or a heavy part that might break free due to vibration
unless it is properly mounted.? For a diode it's a waste of perfectly good ChipQuick.
?
Jerry, KE7ER
?
?
?
On Thu, May 22, 2025 at 06:59 PM, Evan Hand wrote:
The QMX series of radios uses a 6-layer PCB. Making the drilling hole larger could cause gaps in the internal layers. It would be better to use a thin lead and solder the fat lead above the board. Look at the board trace pictures and the schematics to verify that the connections are still there.
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Re: Why no AGC for digital modes, as other modes?
? Re: Why no AGC for digital modes, as other modes?
From: ajparent1/kb1gmx
Date: Thu, 22 May 2025 21:27:50 EDT
My entire post that follows is from a self described obstinate and
ancient analog rf weenie:
It was said: "So a digi band has a couple of very strong signals it
tends
too make the weak ones impossible to detect."
..."It was a big problem with early receivers with a strong agc
system rather than large dynamic range." (that caused AGC pumping).
My immediate response is what is the minimum discernible signal
difference between single tone cw with selectable AGC and
sequential single tone FT8 without? What is to be gained, without
selectable AGC, by increased IMD and gain compression
with digital modes vs the use of AGC when operating cw?
I have read many a post, in other group postings, regarding what is,
to me, apparent fantasy regarding FT8.
I? await my comeuppance, as a relative digital ignoramus.
?
Though I differ, I thank you for your well stated and relevant
reason regarding your apparent choice of no AGC for single tone
modes.
Regarding my inquiry, it is far more relevant than "turn down the
volume".
Given the relatively large dynamic range of my ancient FT-990 and
TS-790A (and today's receivers? my QMX+?), and the?selectable
characteristics of AGC implementation, I have noticed no
undesirable effects regarding the use of AGC that effected the
receiver
?rf gain, whether I use cw or ft8/FT4 on hf, vhf, or uhf.
For my needs and desires, all I request is the ability to use AGC
as I choose, complete with a more pleasant listening environment
and an
AGC and S "meter" that works.
As far as I am concerned, the topic is closed.
Da Ol' Curmudgeon,
?????????????????????? ? ? ? ?? ??? wa4hei
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QMX+ firmware feature request
I'll start by saying I think if this as a "nice to have" change:
?
I use a manual antenna tuner and the built in SWR bridge is great for checking the state-of-tune. In a (my) "perfect world", the "Tune SWR" would present a full width, bottom line, bar graph of the VSWR, rather than a single number. It's hard (for me) to spin the tuning knobs looking a flickering numbers.
?
Just a thought.
?
Thank you Hans for producing such a great radio!
--
73,
Brent DeWitt, AB1LF
Milford, MA
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Re: Release of version 2.0 of ABS solution for QMX+ (Automatic internal antenna tuner, internal battery and internal speaker with audio amp)
#PSU
#QMXplus
#audio
#ABS
#ATU
Interested for a Europe group buy
Great work this addition to the QMX+, perhaps something to add to the shop.
--
73 de PE5ED / JO22
817 and QMX+
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Thanks Greg. I will try that next time. I have tried to use low temp solder to help clear the ground connections but it did not work. I managed to use a push-pin and a very hot iron to open those up.
Tony
AD0VC
toggle quoted message
Show quoted text
I've successfully cleared holes with a hand pin vise and an assortment of really teeny drill bits. Start with an obviously too small bit and work up in size until the component just fits. Go slow, clear the swarf often.?
Successfully opened up many in QDXs, QMXs and 50Watt amps.?
Lately though, I bought some Chip Quick brand desolder braid. Just needed some more and decided to try theirs. Fabulous stuff! No extra flux needed and it really pulls solder away. I flow extra fresh solder on the hole in question and then apply the braid
and iron quickly. Tug the long end up a bit and hold while it flows up the braid. Works a treat as the Brits say.?
Greg KI4NVX?
On Fri, May 23, 2025 at 8:33 AM, mux_folder2001 via groups.io
<canthony15@...> wrote:
Thanks Hans. The hole diameter is good to know. I used my old dial micrometer, which is calibrated in inches, to measure a diode from the kit and then did a bad mental conversion to metric. Still, much smaller than a regular 1N400x. When you clear the holes
with a solder sucker, it leaves some solder still in the hole which has to be cleared out to get the fat diode leads in there.
73,
Tony
AD0VC
Hi Tony
I just measured one of the 1N4007 diodes from the kits, the wire diameter is 0.4mm. According to the PCB CAD program (I just checked) the footprint for these diodes specifies a 0.8mm drill size. So the holes ought to fit 0.7mm wire too.?
On Fri, May 23, 2025 at 5:07?AM mux_folder2001 via
<canthony15= [email protected]> wrote:
Nothing fancy on these connections. Top layer and bottom layer traces only. I just checked with the meter and all is well. My question really was about the diodes. Where do you get 1n4007 diodes with .3mm leads?
Tony
AD0VC
Tony,
?
The QMX series of radios uses a 6-layer PCB. Making the drilling hole larger could cause gaps in the internal layers. It would be better to use a thin lead and solder the fat lead above the board. Look at the board trace pictures and the schematics to
verify that the connections are still there.
?
73
Evan
AC9TU
|
I've successfully cleared holes with a hand pin vise and an assortment of really teeny drill bits. Start with an obviously too small bit and work up in size until the component just fits. Go slow, clear the swarf often.?
Successfully opened up many in QDXs, QMXs and 50Watt amps.?
Lately though, I bought some Chip Quick brand desolder braid. Just needed some more and decided to try theirs. Fabulous stuff! No extra flux needed and it really pulls solder away. I flow extra fresh solder on the hole in question and then apply the braid and iron quickly. Tug the long end up a bit and hold while it flows up the braid. Works a treat as the Brits say.?
On Fri, May 23, 2025 at 8:33 AM, mux_folder2001 via groups.io <canthony15@...> wrote:
Thanks Hans. The hole diameter is good to know. I used my old dial micrometer, which is calibrated in inches, to measure a diode from the kit and then did a bad mental conversion to metric. Still, much smaller than a regular 1N400x. When you clear the holes
with a solder sucker, it leaves some solder still in the hole which has to be cleared out to get the fat diode leads in there.
73,
Tony
AD0VC
Hi Tony
I just measured one of the 1N4007 diodes from the kits, the wire diameter is 0.4mm. According to the PCB CAD program (I just checked) the footprint for these diodes specifies a 0.8mm drill size. So the holes ought to fit 0.7mm wire too.?
On Fri, May 23, 2025 at 5:07?AM mux_folder2001 via
<canthony15= [email protected]> wrote:
Nothing fancy on these connections. Top layer and bottom layer traces only. I just checked with the meter and all is well. My question really was about the diodes. Where do you get 1n4007 diodes with .3mm leads?
Tony
AD0VC
Tony,
?
The QMX series of radios uses a 6-layer PCB. Making the drilling hole larger could cause gaps in the internal layers. It would be better to use a thin lead and solder the fat lead above the board. Look at the board trace pictures and the schematics to
verify that the connections are still there.
?
73
Evan
AC9TU
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Re: OoT-RADIO HIFI TAMAGUCHI
You need to be careful, it's probably not legal to train an LLM on copyrighted books.
?
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Thanks Hans. The hole diameter is good to know. I used my old dial micrometer, which is calibrated in inches, to measure a diode from the kit and then did a bad mental conversion to metric. Still, much smaller than a regular 1N400x. When you clear the holes
with a solder sucker, it leaves some solder still in the hole which has to be cleared out to get the fat diode leads in there.
73,
Tony
AD0VC
toggle quoted message
Show quoted text
Hi Tony
I just measured one of the 1N4007 diodes from the kits, the wire diameter is 0.4mm. According to the PCB CAD program (I just checked) the footprint for these diodes specifies a 0.8mm drill size. So the holes ought to fit 0.7mm wire too.?
On Fri, May 23, 2025 at 5:07?AM mux_folder2001 via
<canthony15= [email protected]> wrote:
Nothing fancy on these connections. Top layer and bottom layer traces only. I just checked with the meter and all is well. My question really was about the diodes. Where do you get 1n4007 diodes with .3mm leads?
Tony
AD0VC
Tony,
?
The QMX series of radios uses a 6-layer PCB. Making the drilling hole larger could cause gaps in the internal layers. It would be better to use a thin lead and solder the fat lead above the board. Look at the board trace pictures and the schematics to
verify that the connections are still there.
?
73
Evan
AC9TU
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Roy Ashkenaz
KK4ITX John
Brent DeWitt