Hello, I am trying to build this version from scratch, but the receiver section is extremely insensitive; in fact, when I connect a ground, the signals disappear entirely. I am using a 2N2222 transistor, with a 20µH inductor in the collector circuit and a 100µH inductor in the base-emitter. Do you have any idea what I might be doing wrong? Thanks for your help.

I built the DDS using an ATMEGA328P chip and an Si5351; the CLK0 output is configured for 2 mA, providing approximately 0 to +3 dBm (roughly 1–2 mW).

The antenna is a 10-meter long-wire, positioned at a height of 6 meters and equipped with an impedance matching network; even so, I can only hear telegraphy (CW) stations at a very low volume.

When increse R13 the lm386 oscillate.

Hello!
A great deal depends on the type of transistor used, and the 2N2222 is not the best choice.
I have achieved good results using KT606 and KT610 transistors, though it is unlikely that these will be available to you.
For resistor R1, you should use a multi-turn potentiometer, as the adjustment of the signal level coming from the synthesizer (or generator) requires very fine, precise control.
Any "Micro" transceiver—or a variation thereof—is not a device with a highly sensitive receiver; therefore, you need antennas designed for specific frequency bands.
A 10-meter length of wire is insufficient for the 40-meter band and will have very low efficiency.
While you could certainly tune a 10-meter wire antenna to resonance, it would remain inefficient—especially when it comes to receiving stations using a "Micro" transceiver.

Soviet medium-power transistors KT606 and KT610.
Look for analogs...

In this circuit, the active filter based on the LM833 operates without gain.
Feedback can be added so that this operational amplifier provides some gain.

I tried placing a potentiometer in series with the 10k resistor emitter; by increasing the total value to approximately 40 kilohms, the sensitivity improved, allowing me to pick up more stations.

I will replace R1 with the multi-turn potentiometer you mentioned and try to improve the antenna.

KT606 and KT610 transistors are impossible to find here in Mexico; I might be able to buy a pair for about 5 dollars, plus shipping costs from Bulgaria:

www.ebay.com/ itm/183777002187

Thank you very much for your reply and for sharing your wonderful designs.

Hello amigo!
I have asked AI what is the best substitution for KT606 and KT610. His answer was:
KT606 – 2N5090, MRF515, MRF627
KT610 – 2N5109, 2N6135, BFW16
Those transistors are old, may be produced in 70-80 years of former century.
You may ask AI to find more modern transistors available in MEXICO.
Serge RW3DF

Yes, that is precisely why I suggested looking for alternative options in my previous response.

One of the sellers on our Ozon platform listed some similar analogs:
2N5090 and MRF515

By the way, with these transistors, the power in transmit mode will be noticeably higher.

Hi, RW3DF

I also asked the AI, and it suggested Motorola 2N2866 transistors; I happen to have some, so I’ll test them later.

Thank you very much for your help.

I’ll try the 2N2866s from Motorola; if that doesn’t work, I’ll look for the ones you suggested.

Thanks (Gracias amigo).

Hello!
I added the multi-turn potentiometer and the Motorola 2N3866 transistor. After adjusting the emitter potentiometer and the multi-turn potentiometer, reception improved significantly. I haven’t tested it for C.W. yet; I’ll try that later tonight.

Here is a video of it in operation:

sbj.edu.mx/videos/dds-microtx.mp4

Thanks for the help.

ili пишет:
I’m glad to help you,
and I’m happy about your success!

¡Buena suerte con el montaje de tu emisora ​​de radio, querido amigo!