Posts by DL9SCO

    Hallo zusammen,


    hier noch eine gute Nachricht von Hans Summers, für alle die den 1117 nicht (oder nicht mehr, Hi!) mögen:


    Wie ja Hans sehr akribisch dokumentiert hat ist nicht der verwendete 1117, sondern ein falsch bestückter Kondensator C38 die Ursache allen Übels.

    Trotzdem wird ab der nächsten Produktionscharge der 1117 ersetzt durch einen 78M05 in einem TO-252 Gehäuse.


    Dadurch wird zusätzlich etwas mehr Sicherheit erreicht, wenn versehentlich kurzzeitig mal eine etwas höhere als die spezifizierte Versorgungsspannung angelegt wird (was dann die Endstufe mit derzeit schon ca. 4,5 W bei 12V allerdings dann auch nicht lange vertragen dürfte).


    Ich finde, das ist im Sinne einer Produktverbesserung eine sehr gute Lösung, die gleichzeitig eine schnelle Reaktionsfähigkeit von QRPLabs zeigt.

    Hello Evan, all


    I have done some detailed testing of this 10uF 10V MLCC capacitor...


    First of all, this is a good quality MLCC 10uF capacitor, made by Samsung. I have used Samsung Galaxy phones for the last 5 years so I like Samsung. But this is merely coincidence. Anyway. Here's what I found.


    1. Capacitance vs Voltage


    Refer to the attached graph which shows my measured capacitance vs voltage for each of the three capacitors under consideration:

    • 10uF 10V MLCC Samsung 0805 SMD, which is installed on the board.
    • 10uF 16V electrolytic through-hole, used in the QCX+ and QCX kits, and which is a recommended modification capacitor
    • 10uF 35V tantalum through-hole, which will be supplied with some QCX-mini kits and is a recommended mod capacitor

    Experimental method: I wired a tactile push-button switch in series with the cap, and a 100K resistor across the capacitor; then push the button to charge the capacitor (from a variable voltage supply) then measure the voltage decay on my oscilloscope and use the oscilloscope cursors to measure the time required for a 10% decay in voltage. Use the formula for capacitance voltage decay to calculate the capacitance. Repeat for various supply voltages and plot the graph.


    The notable result is that the 10uF electrolytic and tantalum capacitors measure very close to 10uF and show little if any variation with supply voltage. What slight variation there is, could be measurement error. The MLCC 0805 SMD 10uF 10V capacitor shows an enormous variation in capacitance with voltage; at 14V supply the capacitance is 1.3uF. I believe this is normal and the rated "10uF" value is the small-signal value.


    For this application of a capacitor at the supply voltage input to the voltage regulator, if an MLCC were to be used then the rated voltage ought to be many times higher than the operating voltage. A more suitable capacitor for this position in the circuit is electrolytic or tantalum.


    2. 10uF 10V 0805 Samsung SMD capacitor failure mode and voltage


    I applied voltages up to 31.6V (the upper limit of my 30V 5A linear variable bench power supply), each time for several minutes (steady) and rapid pulsed on/off operation and I could not force this capacitor to fail at all. I also found in the capacitor datasheet some mention of "withstand voltage" testing at 2.5x the rated voltage.


    I do have two PSUs so theoretically I could wire them in series and continue up in voltage to try and force failure. But given 31.6V is so so far above the likely operating range of the radio I think this is unnecessary and would cause some considerable complication in my lab setup here (e.g. is it correct and safe to wire the two PSU outputs in series etc).


    It leads me to the unprovable conclusion that the capacitor is quite unlikely to fail at normal QCX-mini voltages in the 12-14V range (or even outside that).


    I know you will say that if it is operated beyond its specified rating then its lifetime will be reduced... I have no way of testing that in a reasonable timescale, but I think the fact it doesn't fail at 2.5x the voltages we want to use it at, provides a significant and sufficiently safety margin.


    3. AMS1117 voltage regulator failure voltage


    During this testing I also had an AMS1117 voltage regulator IC connected to the same supply voltage. It was connected permanently, not downstream of the push-button that was used for the capacitor experiments. As I gradually ramped up the voltage for the 10uF 10V capacitor capacitance value measurement graph, I also observed the state of the AMS1117. At 28V, the AMS1117 failed. I imagine it would fail at lower voltages under pulse conditions such as power-on. The failure mode was as usual, a short-circuit which is nasty, but I don't think it is unique to the AMS variant of the 1117.


    4. AMS1117-5.0 source


    I also investigated with the PCB A and supply chain and was informed that the AMS1117-5.0 was procured from a reliable and reputable source, and has been used many times before in various PCBA without issue. I do not believe the AMS1117 is at fault here, it is not a fake or a poor quality device.


    CONCLUSIONS

    1. There is no necessity at all to change the AMS1117 voltage regulator. It is adequate for the job and I do not think there will be any problem operating it with supply voltages up to 15V or perhaps a bit more. Changing the AMS1117 is likely to incur risk of PCB damage. Changing it to a different brand 1117 will not solve the problem or provide any benefits.
    2. The problem is clearly the 10uF capacitor C38. It isn't a bad quality component (Samsung), it's just the WRONG component. Somewhere in the supply chain the 10V rating was used and it should have been a 25V device. Even then, it is probably a design error to use MLCC at this point, it should have been an Electrolytic or Tantalum.
    3. The recommended solution remains to install the 10uF electrolytic through-hole or tantalum capacitor in parallel with C38, and not to remove C38. C38 does not seem likely to fail so can be left in place. Removing C38 and replacing it with something else (should be electrolytic or tantalum), or replacing the voltage regulator with something else, will risk damaging the PCB and you will be in uncharted, untested territory. Do it if you want, it's your radio and we are all experimenters... but don't cry later if it doesn't go well ;-)

    Executive summary:

    Just add a 10uF electrolytic or tantalum and BE HAPPY.


    73 Hans G0UPL

    http://qrp-labs.com

    Hallo zusammen,


    es gibt neue Infos zum Thema Spannungsregler beim QCX Mini:

    Offensichtlich wurde bei der Fertigung der Leiterplatten durch die Bestückungsfirma die Stücklistenspezifikation von C38 nicht beachtet - es liegt wohl definitiv ein Fertigungsfehler vor.

    An Stelle des spezifizierten 25V Kondensators wurde versehentlich ein 10V Typ verbaut. Die Kapazität eines X5R-Kondensators ist spannungsabhängig, die Kapazität verringert sich mit steigender angelegter Spannung. Daher ist Hans Summers nun der Meinung, dass die Kapazität von C deutlich unter 10uF liegt und daher nicht ausreicht, um den Spannungsregler 1117 zu schützen. Er rät davon ab, den 1117 auszutauschen, da dies normalerweise nicht nötig sei und gewisse Risiken für die Beschädigung der Leiterplatte birgt.

    Allerdings gibt es gerade die Überlegung, bei der nächsten Fertigungsscharge einen 7805 an Stelle des AMS1117 einzusetzen um bei der Eingangsspannung mit etwas Reserve auf der sicheren Seite zu sein.

    Hier die Original-Info von Hans Summers:


    Hi all


    I thought you may be interested to see this photo attached. I dug into the records of the assembly facility which soldered the PCBA in the QCX-mini, and managed to get the actual photo of the reel that was installed in the machine for the QCX-mini assembly. It's very nice that such photos are captured and retained.


    Note the manufacturer Samsung (should be OK) and the part number CL21A106KPFNNNE. You can find the datasheet for this capacitor here: https://datasheet.lcsc.com/szl…CL21A106KOQNNNE_C1713.pdf


    At page 4 you can see an explanation of the part code from which we can see:

    • CL = Multi Layer Ceramic Capacitor series
    • 21 = size, SMD 0805
    • A = Class II dielectric X5R
    • 106 = Capacitance 10uF
    • K = Tolerance +/- 10%
    • P = rated voltage 10V
    • F = Thickness code 1.25mm
    • N = normal product Ni/Cu/Ni battier/ Sn 100% termination plating
    • N = Normal product code
    • N = Control code (reserved for future use)
    • E = Packaging code, Embossed 7" reel

    What should certainly be noted is the 10V rating of this capacitor. An X5R capacitor exhibits capacitance dependent on applied voltage, capacitance DECREASES as the applied voltage increases. This capacitor is already beyond its rated 10V and therefore the capacitance would be expected to be significantly under 10uF, and therefore inadequate to protect the '1117 voltage regulator.


    The manufacturing error was therefore at the assembly facility who did not follow my BOM specification (25V rated capacitor) and used this lower voltage capacitor reel.


    I also believe this further reinforces with a sound theoretical reasoning, the recommended solution of fitting a 10uF electrolytic or tantalum capacitor at the voltage regulator input. It remains the case that there is no evidence to suspect that the AMS1117-5.0 voltage regulator is at fault or is in need of replacement, and replacement is NOT recommended since it will risk damaging the PCB unless you are quite experienced in such matters.


    73 Hans G0UPL

    http://qrp-labs.com


    Liebe QCX Mini Bastler und Mitleser,


    es gab jetzt eine ganze Menge manchmal etwas spekulativer Äusserungen rund um das Gerät, das Design der Schaltung, die Qualität und Herkunft der Bauteile und die Inhalte der Datenblätter. Das ist alles gut und recht, bitte denkt aber auch daran, dass Hans diesen Fehler garantiert nicht absichtlich eingebaut hat. So etwas kann in einer Entwicklung durchaus mal passieren, wichtig ist dass in einem solchen Fall schnell reagiert wird, eine passende Lösung erarbeitet, die entsprechenden Gegenmaßnahmen getroffen und die betroffenen OMs informiert werden.

    Dies alles hat Hans Summers in mustergültiger Art und Weise umgesetzt. Die Nacht, in der er den Fehler realisiert, entsprechende Tests und Messungen gemacht sowie einen einfachen und wirkungsvollen Workaround publiziert hat, war für ihn sehr kurz - ja, manchmal müssen dann in einer solchen Situation dann "eben" leider auch mal 3 Stunden Schlaf reichen.
    Man muss sich auch immer vor Augen halten dass hier kein multinationaler Konzern am Werk ist, sondern ein kleiner Einzelunternehmer mit viel Idealismus und Spaß am Hobby!

    Es ist meiner Meinung nach heutzutage durchaus üblich, dass man sich entsprechende Unterlagen zum Bau eines Gerätes in aktueller Version im Internet besorgt und das Aufbauhandbuch dort herunterlädt um eben eine hohe Aktualität gewährleistet zu bekommen. Das ist ähnlich, wie wenn man sich bei einem neu gekauften technischen Gerät natürlich erstmal die aktuelle Firmware herunterlädt und installiert.

    Dieses Vorgehen hat sich bei den beiden Vorgängern des QCX und den vielen anderen Projekten von QRPLabs (Ultimate 3 Kits usw. ) sehr bewährt. Genauso bewährt hat es sich, eventuell auftretende Probleme oder missverständliche Passagen in der Anleitung in der Gruppe zu diskutieren (hier QRPLabs@groups.io) - zum einen entlastet es einen "Einzelkämpfer" wie Hans, der sowieso jeden Tag schon sehr viele Fragen beantworten muss, zum anderen lernt man sich in der Gruppe kennen und auch gegenseitig zu helfen. Das ist auch bei anderen Herstellern wie z.B. Elecraft nicht anders - und hier im QRPForum läuft es doch im Prinzip auch genauso.

    Deswegen kann ich Kritik in der Art von "...wäre nicht meins" hier nicht nachvollziehen. Die Zeiten in denen man z.B. einen Heathkit-Transceiver, den man mit Hilfe eines gedruckten Heftchens mit Liste zum Abhaken aufbaut, sind schon länger vorbei und dazu sind die Geräte heute auch meist einfach zu komplex.

    Ich denke auch man muss beachten, dass hier nun ein fertiger Bausatz auf dem Markt ist, für dessen bereits ausgelieferte Exemplare es der schnellen und pragmatischen Lösung eines Problems bedurfte -

    da hilft es dann nicht unbedingt, darüber zu lamentieren welchen Regler man "hätte" einsetzen sollen und wie man doch alles viel besser machen "hätte" können.

    Hans hat bereits viele tolle Geräte entwickelt und mit seinem Prinzip des QCX Transceivers mit eingebautem "Messlabor" Standards gesetzt, die es in dieser Form bisher nicht gab. Der QCX, der QCX+ und der QCX Mini wurden von mir aufgebaut und liefen auf Anhieb problemlos, ebenso wie zwei Ultimate 3 Kits, die GPS Antenne und das Relais Kit hierzu. Die Schaltungen von Hans sind sehr durchdacht, effizient und seine Ideen oft einmalig - und wenn ihm jetzt mal was schiefgeht würde ich mir sehr wünschen dass sich alle vielleicht einfach wieder etwas entspannen und auch entsprechende Nachsicht walten lassen könnten.

    Genug der deutschen Worte - hier folgen nun die Englischen. Das folgende Statement habe ich heute Abend von Hans erhalten und leite es im Original weiter - in der Hoffnung dass damit viele unklare Sachverhalte geklärt geklärt und mancher Spekulation damit ein Ende bereitet wird:


    Dear friends,


    Please do not concern yourselves overly about the quality of the components in the QCX-mini or other QRP Labs kits. Those of you who already own a QRP Labs kit will already be aware that the quality is consistently high. I receive many compliments on the overall quality, PCB quality, and enclosure quality.

    Our components are sourced from many different places. The care taken in sourcing, does depend on the criticality of the component. We do a lot of testing. For example, all NP0 capacitors are made by Vishay and sourced from Digikey US. All toroids are micrometals sourced from http://kitsandparts.com in US. Si5351A are from Mouser (this time... sometimes Digikey).


    Engineering and optimization and testing takes many months. If I were to simply buy the most expensive part of everything, from Digikey, and follow the application circuits of all the datasheets precisely, the radio would cost $150 not $55. Instead I invest my time heavily, to test and control every possible aspect of the design and components. Some components are indeed sourced from reliable and tested sources in China. The PCBs are also made and assembled in China. Every time I source something externally I must deal with import documentation and taxes to get the items into China. Just as I must deal with import documentation and taxes to get the toroids and NP0 through-hole capacitors to my QTH here in Turkey. Believe me, the costs soon multiply up exponentially.

    The AMS1117 datasheet http://www.ams-semitech.com/at…File/AMS1117_20120314.pdf lists 18V as the maximum rating. I am aware that there is another AMS datasheet which lists 15V. Unfortunately, as anyone who spends as much time as I spend reading datasheets, will know: it is often difficult to compare between different manufacturers of the same industry standard device, and often even one manufacturer's own datasheets are inconsistent with themselves or earlier versions. Interpretation of datasheets is not always trivial.


    The '1117 datasheets mention 22uF load capacitor to suit all operating conditions but go on to say that if a bypass capacitor is not connected at the voltage adjust pin, lower capacitor values are suitable. We have here a fixed +5V regulator, not an adjustable type, and 10uF is suitable. I was caught out by the input capacitor type which is inadequate in some circumstances. Frankly, I had not considered testing to destruction the use case scenario where an operator rapidly switches on/off his power supply, or inserts (with intermittent connection) a power plug which is live. I would not normally operate like that.


    The '1117 does not need a protection diode. The datasheet makes this clear. Even surge currents of 50-100A can be handled safely by the internal diode. Only in the most extreme cases would a protection diode be needed. In the event of a short to ground at the power input, assuming a highly rapid and efficient power supply crowbar circuit and very short wiring, there would still be no issue since the '1117 is preceded by diode D33 which acts as a reverse polarity protection diode.


    Good engineering is not about building a sports car that weighs 5 tons and where every structural member is reinforced in triplicate. It is about calculation and optimization to achieve the desired specification and then with a satisfactory safety margin. Most markets are highly price sensitive, consumers do demand low prices; amateur radio kits are no exception to this. It is easy in hindsight to point to a particular troublesome component and how a different one would have cost 10 cents more only. But the benefit of hindsight is not available to the designer and producer, and it is not economically feasible to multiply by 5, the cost of every component in the design, or add precautionary components everywhere with extreme pessimism.


    There is no problem either with the LM4562 or the OPA2277 op-amps. Not on the QCX-mini, and not on the 11,500 kits of the QCX and QCX+ that have already been sold in 3 years to many very happy constructors. Owners of these kits recognize the exceptional performance to price ratio, and many times I have received feedback that the performance exceeds that of the owner's $$$$ Yaesu, Kenwood, Icom etc.


    We also do not know of any common failure mode of the Si5351A in normal operation in the QCX, QCX+ or QCX-mini kits. The diode dropper trick is cheeky, but it works and is reliable. The same applies to the use of the SDA pin in the QCX firmware (note that uSDX is not a QRP Labs product nor is technical support provided by QRP Labs).


    All kits we are now shipping out are being shipped with either a 10uF electrolytic or a 10uF 35V tantalum capacitor. Although the datasheets repeatedly refer to tantalum I personally admit to a preference for electrolytics. All kits which were shipped out prior to this problem becoming known, will receive an email from me explaining the potential problem under the unusual operating condition (live power plugging or rapid on/off toggling) and recommending the modification; furthermore if the constructor has no suitable capacitor to hand we will send one at no cost. If the constructor has already suffered damage to his QCX-mini kit, having read an earlier revision of the assembly manual, and before receiving the notification about the recommended change, we will of course offer him a replacement QCX-mini kit at no cost.


    I would like to point out that QRP Labs has an excellent reputation for performance, quality, low price, and high customer service. Owners of QRP Labs equipment will know this first hand. Google will also reveal the same story. Even the largest manufacturers can suffer unexpected issues with their new product, this is why product recalls are very common, whether it is a car, a washing machine, or a television. Therefore one should not be over-critical of a small family business with much more limited resources, particularly as this is a very minor issue with a very easily applied solution, that is described in the documentation.


    73 Hans G0UPL

    http://qrp-labs.com

    Hier für alle Nachbauer die Nachricht von Hans Summers, es geht um den unbedingt notwendigen Einbau eines zusätzlichen 10uF Kondensators in den QCX Mini (QSP de DL9SCO):


    Hi all


    With great sorrow I have to report that a problem has arisen with the QCX-mini; I have investigated and found a simple modification which prevents the problem. This should be viewed as an essential change for ALL QCX-mini constructors.

    Problem:


    Four different constructors have reported their QCX-mini destroyed itself in a little puff of smoke. There was some commentary that this occurred on plugging in the power connector and in one case switching on/off rapidly.

    Investigation:

    SMD capacitor C38 is found to be not up to the job. Presumably of a type which is inadequate for the task. On a high speed oscilloscope, when the power is applied a large spike of up to 1.5x the supply voltage is observed, with a duration of the order of 0.1us. Where a supply voltage of 12 or 13.8V is used, the spike can exceed the maximum voltage rating of the AMS1117-5.0 voltage regulator IC and cause it to become unstable and self-destruct.

    The failure mode of the AMS1117-5.0 is to connect its input to its output. This applies +12V to the +5V rail of the QCX-mini circuit, to which is connected the FST3253 1:4 MUX, the Si5351A Synth, the 74ACT08 PA driver, the LCD module, and the ATmega328 microcontroller. OUCH! The Si5351A synthesizer IC fails internally fusing its supply line to ground. That results in a high current flow through D1 and D2, the voltage dropper diodes which power the Si5351A via the +5V rail. One of these diodes fails first under the stress of the very high current flow, and this diode is what generates the "Psssst" sound, the smoke, and the bad lingering smell.

    Solution:

    The problem can be solved by soldering a 10uF electrolytic or tantalum capacitor from the voltage regulator input to ground (in other words, in parallel with the pathetically inadequate C38 SMD 10uF capacitor).

    In testing with the 10uF electrolytic capacitor installed, I set my bench PSU to 14V and rapidly inserted and removed the 2.1mm power connector to the QCX-mini board. Without fully inserting it, only pushing it just about enough to make contact. My oscilloscope was connected to the voltage regulator input and output pins. No voltage spikes were seen and although I continued this attack for 10 seconds or more, no failure occurred.

    I then removed the 10uF electrolytic capacitor and repeated the test. This time after several seconds, the failure occured: manifested by the statutory "Pssst" sound, smoke which in this instance arose from diode D1, and the bad lingering smell of burned diode. After the event a small crater was visible on the top of diode D1 and another on the FST3253 MUX. Result: dead QCX-mini requiring extensive repairs.

    I then soldered a 10uF capacitor to another QCX-mini (my last, gulp) and again tried to kill it with repeated intermittent connection to my 20A bench power supply set to 14V and again, there was NO failure.

    Modification:

    The modification is described in the 1.04 version of the manual http://qrp-labs.com/images/qcxmini/manual_1_04.pdf in section 3.42 at pages 67 and 68.

    The modification requires a small electrolytic or tantalum capacitor, value at least 10uF and rated at least 16V. The capacitor needs to be small enough to lie down in the space between the voltage regulator, op-amp IC10, and the power connector; it needs to be thin enough to not obstruct the gain potentiometer when the Controls PCB is plugged in. Practically speaking this means the capacitor should be no more than 5.5mm diameter and 9mm long. If you are familiar with the 10uF capacitor used in the QCX+ kit, this capacitor fits perfectly, it has diameter 4mm and length 7mm.

    For those people who have already received their QCX-mini kit, or those whose kit is in the post... if you could find a suitable capacitor in your junkbox or local supplier, that would be much appreciated here. But if not, please email me and I will send you a suitable capacitor. For all future orders to be shipped out, we will include a suitable 10uF capacitor with your kit.

    73 Hans G0UPL

    http://qrp-labs.com

    Hallo Dietmar,


    mit Magie hat das eigentlich nicht viel zu tun - eher mit dem Lesen der für den neuen QCX Mini relevanten posts von QRPLabs auf Groups.io, Hi!
    Es gibt wohl leider ein Problem mit dem QXC Mini, der sich beim Einschalten mit einem hässlichen kleinen Rauchwölkchen in die ewigen Transceivergründe verabschieden kann.
    Hans Summers hat dafür gestern Nacht bereits einen workaround entwickelt und schrieb hierzu heute in den frühen Morgenstunden:


    Hi all


    With great sorrow I have to report that a problem has arisen with the QCX-mini; I have investigated and found a simple modification which prevents the problem. This should be viewed as an essential change for ALL QCX-mini constructors.

    Problem:


    Four different constructors have reported their QCX-mini destroyed itself in a little puff of smoke. There was some commentary that this occurred on plugging in the power connector and in one case switching on/off rapidly.

    Investigation:

    SMD capacitor C38 is found to be not up to the job. Presumably of a type which is inadequate for the task. On a high speed oscilloscope, when the power is applied a large spike of up to 1.5x the supply voltage is observed, with a duration of the order of 0.1us. Where a supply voltage of 12 or 13.8V is used, the spike can exceed the maximum voltage rating of the AMS1117-5.0 voltage regulator IC and cause it to become unstable and self-destruct.

    The failure mode of the AMS1117-5.0 is to connect its input to its output. This applies +12V to the +5V rail of the QCX-mini circuit, to which is connected the FST3253 1:4 MUX, the Si5351A Synth, the 74ACT08 PA driver, the LCD module, and the ATmega328 microcontroller. OUCH! The Si5351A synthesizer IC fails internally fusing its supply line to ground. That results in a high current flow through D1 and D2, the voltage dropper diodes which power the Si5351A via the +5V rail. One of these diodes fails first under the stress of the very high current flow, and this diode is what generates the "Psssst" sound, the smoke, and the bad lingering smell.

    Solution:

    The problem can be solved by soldering a 10uF electrolytic or tantalum capacitor from the voltage regulator input to ground (in other words, in parallel with the pathetically inadequate C38 SMD 10uF capacitor).

    In testing with the 10uF electrolytic capacitor installed, I set my bench PSU to 14V and rapidly inserted and removed the 2.1mm power connector to the QCX-mini board. Without fully inserting it, only pushing it just about enough to make contact. My oscilloscope was connected to the voltage regulator input and output pins. No voltage spikes were seen and although I continued this attack for 10 seconds or more, no failure occurred.

    I then removed the 10uF electrolytic capacitor and repeated the test. This time after several seconds, the failure occured: manifested by the statutory "Pssst" sound, smoke which in this instance arose from diode D1, and the bad lingering smell of burned diode. After the event a small crater was visible on the top of diode D1 and another on the FST3253 MUX. Result: dead QCX-mini requiring extensive repairs.

    I then soldered a 10uF capacitor to another QCX-mini (my last, gulp) and again tried to kill it with repeated intermittent connection to my 20A bench power supply set to 14V and again, there was NO failure.

    Modification:

    The modification is described in the 1.04 version of the manual http://qrp-labs.com/images/qcxmini/manual_1_04.pdf in section 3.42 at pages 67 and 68.

    The modification requires a small electrolytic or tantalum capacitor, value at least 10uF and rated at least 16V. The capacitor needs to be small enough to lie down in the space between the voltage regulator, op-amp IC10, and the power connector; it needs to be thin enough to not obstruct the gain potentiometer when the Controls PCB is plugged in. Practically speaking this means the capacitor should be no more than 5.5mm diameter and 9mm long. If you are familiar with the 10uF capacitor used in the QCX+ kit, this capacitor fits perfectly, it has diameter 4mm and length 7mm.

    For those people who have already received their QCX-mini kit, or those whose kit is in the post... if you could find a suitable capacitor in your junkbox or local supplier, that would be much appreciated here. But if not, please email me and I will send you a suitable capacitor. For all future orders to be shipped out, we will include a suitable 10uF capacitor with your kit.

    73 Hans G0UPL

    http://qrp-labs.com


    Ich hoffe, das hilft weiter!
    Mni 72 / 73 Hannes

    Tja Jochen,


    man muss es doch voll auskosten, wenn man schon mal was zum Auspacken hat - ist ja schliesslich noch nicht Weihnachten, Hi!
    Ich hoffe, Dein QCX Mini kommt auch bald - bitte den 10 uF Kondensator dann nicht vergessen, sonst gibt's QCX Mini "flambée" :-)