Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
Search
QDX version 1 voltage regulator mod?
|
Greetings from England,?
I built my QDX vsn 1 from the first batch for 9 volts. Tested it and tried it out then put it aside. Now I want to use it for WSPR. I saw a video which recommended replacing the voltage regulator and taking the output from the higher voltage regulator to the lower voltage regulator. Is this really necessary ? I will probably be running it with less than 9 volts as 5 watts output seems a bit excessive.? Has anyone tried using the QDX with a microcontroller for WSPR?? I ordered the latest version for the higher bands yesterday. I’m looking forward to building it.? 73s Steve G0XAR? |
|
Hi Steve Replacing the voltage regulator wasn't necessary. It IS necessary to make sure you fit the 10uF electrolytic capacitor across the 12V supply voltage. If that was done, the AMS1117 should be fine. And even more so, considering that you are using a lower voltage?9V supply.? 73 Hans G0UPL On Mon, Feb 26, 2024 at 12:45?PM Stephen Farthing G0XAR JO92ON97 <squirrox@...> wrote: Greetings from England,? |
|
Steve,
I still have my Rev 1 QDX running.? It is built for 12 volts, but I run it between 8 to 10 volts.? That, to me, supports Hans's statement.? The one mod that I suggest is adding a 1n4148 diode across L14 to prevent the end-of-transmission spike observed on the QDX.?? The AMS1117 regulators have a low dropout voltage, so you can run it at a lower voltage than the 7805 replacement.? It should be good down to just above 6.2 volts.? That gives you a lower power option than the replacement with a dropout at 7 volts. 73 Evan AC9TU |
|
On 26/02/2024 09:45, Stephen Farthing G0XAR JO92ON97 wrote:
I built my QDX vsn 1 from the first batch for 9 volts.Steve, Like Evan I've built mine for 12 volts, run them at 7.5 volts. As I only want 1 watt for WSPR I also have 2 or 3 diodes in series with L14. 4 version 1s, run this way obviously no problem, no PA mods. I run with WSJT-X, one on a Raspberry pi. (I also run a U3S at <100mW for 17-10m, don't think more is needed.) Has anyone tried using the QDX with a microcontroller for WSPR?Do you want RXTX? I guess the WSJT-X functions could be put in a micro, I do not remember anyone doing that as a separate project. 73 Alan G4ZFQ |
|
On 26/02/2024 11:05, Alan G4ZFQ via groups.io wrote:
(I also run a U3S at <100mW for 17-10m, don't think more is needed.)I did not mention my 5th QDX, a V5M for experimenting. It is on a breadboard with a 317 regulator for the PA. I was running at ~1 Watt 5 volts on the PA. I've just tried 2024-02-26 12:12:00 K9AN 3 6483 -28 EN50wc 14097012 17 G4ZFQ ~60mW with 1.2 volts. I claim the lowest power from a QDX with 4 good BS170s:-) 73 Alan G4ZFQ |
|
Alan,?
WSPR Transmit only.? My idea is to get the QDX to transmit WSPR on a frequency and at a time determined by a microcontroller rather than a computer. This would allow the automation of a multi band beacon without tying up a computer.? My “rough” design is to use a rasberry pi Pico with an I2C real time clock. The software would have a hard coded WSPR string (as shown by Andy Talbot and others) ?and a Kenwood TS480 CAT protocol emulator. The Pico would send a message to the QDX using the CAT protocol at a time, duration and ?frequency defined in the code which will use the RTC for timing purposes.? What I don’t know is if the Pico can use its USB interface for serial port communications with the QDX A raspberry pi Zero might be a better option. Using a microcontroller would offer the possibility of switching an appropriate aerial matching circuit as well.? I’m starting to learn Micropython and thought this might be a suitable starter project.? Er, that’s it,? Steve? |
to navigate to use esc to dismiss