Today I was browsing through the SOTA-reflector (the SOTA forum if you like to call it so). I found an interesting post from Richard, G3CWI about a new chinese developed 1W datamode TRX with built-in VOX. So you don't need any CAT to trigger the PTT. I checked out the groups.io thread (DSB transceiver for Digital mode) with lots of useful questions and information. Especially paired with a raspberry pi that would be an ideal SOTA and /P rig I guess.
- Crystal controlled single frequency DSB transceiver for 20m (14.074MHz), 40m (7.074MHz) or 80m (3.573MHz), other frequencies could be added per request. 80m is not ready yet.
- Power supply: 10-14V DC regulated power supply or battery pack, 12V is recommended, center positive, reverse polarity protection available
- Current consumption in RX: about 15mA at 12V
- Current consumption in TX: about 300mA at 12V
- RF output: about 1W for 40m band at 12V, and a bit less for 20m band
- Spurious suppression: no worse than -50dBc
- Antenna connector: BNC connector, 50 ohm
- Audio in connector: 3.5mm mono, at least 600mV to activate VOX, connects to headphone connector at PC sound card, no dedicated PTT connector is required
- Audio out connector: 3.5mm mono, connects to microphone connector at PC sound card
- Amber LED: TX status
- Green LED: RX status
- Frequency accuracy: -600 Hz ~ + 200 Hz
- Frequency stability: Okay for FT8 mode per test.
- If the optional heater resistor R20* is added, after warm up, long term frequency stability in 10 min will be improved at the cost of acceptable short term frequency stability sacrifice in 30 sec.
The introductory price is 39 USD for kit including shipping to worldwide. As in the introductory period, you will get audio cable options for free. The earliest possible shipment date is now improved to May 13.
Here are some more detailed shots including the PCB layout:
You can order your D4D DSB Transceiver Kit for Digital Mode (20m/40m available now) here: http://www.crkits.com/
Update October 2023: D4D DSB 1W Kit
After 4 years I found the kit in one of my drawers and built it straight away. The kit is based on a NE602 IC.
In the meantime there were 3 newer versions of the assembly instructions with 2 improvements. I changed a capacitor and added an additional diode to improve the IMD. After one afternoon and one evening it was ready. In the first hour of my test I could directly make 20 QSO. I myself heard Japan well several times. I was heard well within 1,500km, sometimes up to 2,400km. It was a lot of fun and it is even nicer that you can also make real QSOs with it. It's a pity it was lying around for so long.
In the drawer I found a v3 of the QRP Labs QDX 4 band...