Of course I tested the Malahit with the SAR32M antenna / 70cm telescopic antenna directly on the balcony and was positively surprised what I can receive everything, with a simple 70 cm telescopic antenna.
Here I show you the reception with a 70 cm telescopic antenna, which is adjusted with Hi Z and amplified with the Pre Amp of the Malahit. The reception is really amazingly good!
Here you can see the SSB reception with the SAR32M and a 70 cm telescopic antenna. In the 40 m band, the SAR32M, provides about 2-3 S-stages better reception. Amazing is also the extremely good noise blocker.
2 x 18650 mod
First I tested if the Malahit DSP2 can also be converted to two 18650 cells and it is possible. But on some boards standing capacitors were installed. Here you have to make sure that you push the speaker to the edge to create space to the left.
In addition, a small and deep 2 x 18650 holder should be used, as can also be seen in the picture. Here you have to be careful to shorten the soldering lugs to the housing.
BMS proctection for the 18650 cell and the Malahit DSP2
The Malahit DSP2 has no protection functions, like a BMS but it´s using the TP5056 charging controller. The charging controller has some protections functions while and after charging.
I added a cheap BMS to be safe, that my 18650 cell have a long life and is protected against a short circuit or things like this.
Bias Tee function, e.g. to supply an external Pre Amp
Then I tested the Bias Tee option and found that always the battery voltage is output. So from 4V – 3,3V (if the VBAT Standard options is activated). This could be problematic, because the cell voltage is to low for most devices.
Please note: The SMA socket problems are solved, because the developers are using a new SMA socket.
The only problems I had were related to the SMA connector: The included SMA telescope antenna had a too thick inner conductor and then apparently broke the SMA connector.
I then installed a U.FL to SMA adapter, which I still had at home, in the Malahit DSP2 and since then everything is fine again. Strangely, I had to try several of these adapters, until then one worked. With the others I only had reception when I connected the respective antenna to the SMA connector.
The U.FL to SMA cable used by the developers is extremely short and was installed in a sharp bend. So all the time there was a lot of voltage on the U.FL connector. As you can see on the picture, I used an adapter with longer RG316 cable. I also secured the cable to the relay with a small blob of hot glue to prevent the port from being live.
Nikolay makes very good and high quality knobs, e.g. for the Malahit DSP1 / DSP2. With shipping both knobs cost 13 € and can be ordered from him by e-mail: firstname.lastname@example.org
Currently I am working on a Bluetooth mod: I will install a Bluetooth board in the housing of the Malahit DSP2, that I will solder to the 3.5 jack output. So I can then use a Bluetooth headphones or speakers, without an adapter to the 3.5 jack socket, to plug from the outside. I soldered together a small housing for the bluetooth board to avoid possible interference.
The board on the picture can work with the 18650 voltage from 3,0V to 5,5V. I can receive and sent sound, but for the Malahit, only the sending part in needed.
Problems with the Malahit DSP2
The software problems like a wrong voltage are already fixed in the new 2,10 test firmwares. The biggest hardware problem for me was the bad SMA socket, but this problem is also already fixed at newer Malahits DSP2.