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Hi Mike, you may need to add yourself to the dialout group in Linux to get permission to use serial ports. In a (Linux) termninal window, try this: *sudo usermod -a -G dialout username* where

No problem, Hans...I am apparently getting the kits several weeks before I expected them anyway and it will take a while before I find enough time to put them together. I bet you have 1.04 released by

I get a "not found" on this link. Michael 2E0IHW

One of the better presentations I've seen about EFHW antenna design is here: http://hamfest.w7yrc.org/wp-content/uploads/2019/06/EFHWslides.pdf (

Received my U4B yesterday and am trying to communicate with it via PuTTY on an RPi4, alternatively on my Mac. ?I am completely new to terminal emulators, so am soliciting some advice. ?On the Rpi,

Hi Ed No... the new PTT signals are each controlled by I/O pins of the microcontroller that were not previously used, they are not used in 1.03 and so if you use 1.03, the PTT connector signals are

Yes and yes. Steven’s answer is very wise and useful too. If money and physical space were no object, buying the ARRL kit might be a better option, because it comes with everything in the same box.

Hans, Does this mean that the PTT output will go active-HIGH when transmitting when still running firmware version 1.03? I should receive my QDX rev. 3 today in the USPS mail since it was sent from

Hello Martin It's great to see some experimenting around this and I did rather expect that this "new" QRP PA design might see further applications beyond QDX! No, it isn't. A Class-E amplifier

I have had my QDX rev2 on the air since mid-January 2022 and have been quite pleased with its performance. I have made over 2000 FT8 contacts over that period with a Windows 10 computer and a

Steven Dick 4:21am #84345 ( /g/QRPLabs/message/84345 ) , Your posit on turns vs core size is valid to a point.? IF your doing 20M and up 2/14 might actually be better but for 80M

Looking at the schematic, the TX line switches both the drive to the final and the reverse bias to the diode switches in the LPF.? If separate lines from the uC were used for these two functions,

Charles Johnson KF4AYT Because you apparently do not understand series and parallel circuits. R4 is in parallel with the winding of T1, that has a very low resistance and you never See R4 with a

Short answer, yes indeed. For QRP the toroid core can be quite small, one inch or even smaller. For example, the output transformer in the QDX is handling 5W, and it is magnetically equivalent to a

At the risk of extending the off-topic thread, but since you asked, an FT140-43 is fine for QRP but use 3T/21T instead of 2T/14T. Same turns ratio but better primary inductance for the smaller core.

Martin, I was wondering about your capacitors C67, 68. I remember someone suggesting it on the QCX, Hans said no, it must have 0-5V drive. For full power you may need to ensure it can have this, pull

I use a 41 m EFHW for my station and it works great. About 12 m above ground. I was lucky to get a roll of army twin field phone cable. 800 m makes a lot of material to build antennas from. Important

Dear Alan, Thanks! I should have been more clear about what I am actually working on: I am designing a QRP CW transceiver that should provide 5 W from a 2S Lipo (7.4-8.4V). In previous designs, I used

Hi all The Rev3 manual is now published see http://qrp-labs.com/qdx . There are still 187 QDX remaining in the shop http://shop.qrp-labs.com/qdx . We have started shipping QDX kits but getting through

Addendum: The MPS751 can handle 2A as per the datasheet ( https://www.onsemi.com/pdf/datasheet/mps751-d.pdf ), so the main question is how we can drive it to that current with the desired timing of