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Re: QDX and QMX+ (soon at least) what is the max safe swr?
Rather than use a ZM2 (a good unit) I tune the actual antenna for less than 1.5:1
then I can omit the tuner.
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Of course depending on the design of the EFHW some do not tune uniformly
on all bands.
?
--
Allison ------------------ Post online only,? direct email will go to a bit bucket. |
Re: A ¡°pluggable¡± firmware architecture?
It was one of those, for me, yes. _Compute!_ was general, _Compute Gazette_ was specific to Commodore, as I recall, but both tended to have some code for Commodore at various times. Either way, that word processor probably saved my academic career. My handwriting is atrocious; my typing at the time was also atrocious unless I could treat "backspace" like just another key, and my typewriter was manual, so that wasn't an option. Once I convinced Luddite teachers to accept 8-pin dot matrix print in lieu of typewritten papers, things got much, much better... On Tue, Sep 17, 2024, at 19:40, Mike KK7ER wrote:
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Re: QDX and QMX+ (soon at least) what is the max safe swr?
The problem can be there is no acceptable SWR above a small minimum...
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For example when you tak about 2:1 swr the impedance can look like 25 ohms?
and that would cause high current in the finals. or it can be 100 ohms where
higher voltages might be developed.
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That is one point and if its really 50 ohm btu has 25 ohms of capacitive
reactance the impedance is not 50 ohms and that also stresses the transmitter.
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What a small minimum, usually 1.5:1 or less.? depends on how your pushing
the finals.
?
--
Allison ------------------ Post online only,? direct email will go to a bit bucket. |
Re: QMX+ is dead after voltage drops to 5V
#ATmega328
#QMXplus
¿ªÔÆÌåÓýHi Sardar;Page 15 of the Rev 2.00 Assembly manual shows that IC101 is the 78M33 voltage regulator. It is the only 78M33 regulator in the parts list. Page 10 of the Rev 2.00 Assembly manual shows the location of IC101 - near the bottom right corner of the board next to JP201. 73, Steve, N3SB -------- Original message -------- From: me@... Date: 9/17/24 4:43 PM (GMT-05:00) Subject: Re: [QRPLabs] QMX+ is dead after voltage drops to 5V #ATmega328 #QMXplus Only rev1. schematics are available. But on Rev2 there are 4 voltage regulators in different parts of the board. It will be a little dangerous to try to repair the board without schematics.
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73,
Sardar ( AC8L), |
Re: QDX and QMX+ (soon at least) what is the max safe swr?
Tony,
"Your zener fix was one of a few that were discussed way back when. Hans
added diode pads to the schematic so he was OK with this workaround." Hans had a lot of uncertainties about Zeners and never included any. When I got my last QMX, I noticed that those pads were missing on the newer Rev.? ?
I, too, have had no issues with PA failures over the last 6 years and 9 kits. No good answer as to reasons for some having multiple failures.?
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73, Dan? NM3A |
Re: QMX+ is dead after voltage drops to 5V
#ATmega328
#QMXplus
Only rev1. schematics are available. But on Rev2 there are 4 voltage regulators in different parts of the board. It will be a little dangerous to try to repair the board without schematics.
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73, Sardar ( AC8L), |
Re: Winding toroids with a chopstick?
¿ªÔÆÌåÓý
17.09.2024 23:26 Dean - KC9REN
kirjutas:
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Re: QDX and QMX+ (soon at least) what is the max safe swr?
¿ªÔÆÌåÓýYou may use a 3dB or 6dB attenuator between TRX and Tuner to protect the PA. This way the PA will always have a reasonable SWR no matter what the tuner does.BR Gerd DF9TS.
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Re: QMX+ is dead after voltage drops to 5V
#ATmega328
#QMXplus
Hi Greg!
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I have read that portion of the manual too, since I bought QMX+ to integrate the ATU tuner and internal battery. And, as an experimenter, mentally I was ready to accept risks associated and bite the bullet.
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So, I did not think that Nano would cause an appreciable current to be drawn while radio is off and it is powered through the usb.
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Without turning radio off and arduino being powered from QMX+ - all has been working perfectly for couple of weeks. Until I plugged usb to arduino and turned radio off :)? And, I did that on purpose to see the serial debug messages from my code while radio is powering up.
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And before powering arduino from QMX+ and USB on it - it also consistently worked from the protype board and arduino being powered with its own power supply. But grounds between itself and QMX+ were shared. Turning radio on/off did not cause any issue. So, these two bits of a success deceived me :)
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I have a revision 2 board with SMPS integrated. But most of its components are big enough I can resolder them with my fat fingers. Now I will have to troubleshoot to find what is broken on SMPS. Will follow Steve's advise.
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73, Sardar ( AC8L). |
Re: QCX Mini 6 meter beacon stopped transmitting
John, the check arrived today. Thank you. Hope the little box is transmitting !!!! 73 ... Ron On Sat, Sep 7, 2024 at 5:50?AM Ronald Taylor via <wa7gil=[email protected]> wrote:
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Re: QDX and QMX+ (soon at least) what is the max safe swr?
One note¡ the ZM-2 is not an ATU, it¡¯s a manual tuner. On Tue, Sep 17, 2024 at 2:38?PM Tony Scaminaci via <tonyscam=[email protected]> wrote:
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Re: QDX and QMX+ (soon at least) what is the max safe swr?
I second Joe¡¯s selection. I used the ZM-2 to tune my EFHW antenna so all the 40-10 meter WSPR frequencies showed less than 1.5 VSWR. Now I don¡¯t even need to use the tuner for WSPR. The absorptive bridge will keep the QMX safe during tuning. On Tue, Sep 17, 2024 at 2:15?PM Joe via <joates_48323=[email protected]> wrote:
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Re: QDX and QMX+ (soon at least) what is the max safe swr?
Chris, As I've stated many times before, NEVER exceed the absolute?maximum rating of a semiconductor as spec'd by the manufacturer. Doing so is asking for trouble, possibly short term, or maybe a gradual weakening of the device under stress until it fails long term. Furthermore, relying on a manufacturer?underrating their device is a bad idea. I've seen a few manufacturers underrate by as much as 20% but this is not at all typical across the semiconductor industry. You'll find that many devices have very little safety margin relative to their maximum ratings so my advice is to never exceed?the manufacturer's specs under any conditions. As far as current-limiting to 100 uA or so during breakdown testing, I don't think it will save you from?permanent?damage but you can certainly try this on your first DUT and see what happens. If you see some odd behavior after the FET breaks down, you should consider it unreliable even if it seems to work when the voltage is lowered. I always consider breakdown voltage testing as destructive. If you test multiple devices, I'm not sure what the stats will look like unless you're willing to test hundreds of them. The same goes for any TN0110 testing you consider trying. Your zener fix was one of a few that were discussed way back when. Hans added diode?pads to the schematic so he was OK with this workaround.? How many BS170's are you planning to perform breakdown testing on? Tony On Tue, Sep 17, 2024 at 12:48?PM Chris KB1NLW via <chrisrey1=[email protected]> wrote:
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Re: QDX and QMX+ (soon at least) what is the max safe swr?
Hi Chris
That is pretty bad luck. I have been operating QRP labs radios without any mods almost constantly since 2018 and never had any issues with finals. One was also working WSPR non stop.
It is very odd why only some folks suffer from blowning finals, given the vast number of sets Hans has sold.
I would be curious to learn about your antenna and PSU. Do you use an ATM?
I really hope you find the cause.
73s Ted
2E0THH
?? |
Re: QMX+ is dead after voltage drops to 5V
#ATmega328
#QMXplus
¿ªÔÆÌåÓýHi Sardar;Just saw your follow-up message. 1) With 9 - 12 Volts applied to the QMX+ power jack, what voltage do you see at the 3.3 Volt output of IC101 (78M33 3.3 Volt regulator) on plug-in power supply module pcb #2 when you press the power button? 2) With 9 - 12 Volts applied to the QMX+ power jack,?what voltage do you see at any of the VDD pins on the main board when you press the power button? 73, Steve, N3SB? -------- Original message -------- From: me@... Date: 9/17/24 10:55 AM (GMT-05:00) Subject: Re: [QRPLabs] QMX+ is dead after voltage drops to 5V #ATmega328 #QMXplus Some details:
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Correction: Arduino on dev board was powered from Vcc (5V) on JP106.
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Firmware was 27.
Can not go to firmware update mode even with the jumper wire (Aux2 to ground).
When plugged to PC - no COM port to try putty. So, board exhibits a brain death.
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When 12V applied and PWR encoder is long pressed - voltage on JP106 from VCC and GND goes to 0.1V then gradually within few sec drops to 0V.
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Any help would be appreciated.
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73,
Sardar ( AC8L). |
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