Hello everyone. After a few months of work, I have finally completed the entire process of replicating the Pebble HF, from design to testing. In this article, I will describe the background for starting this project and some of the problems I encountered during the replication process. I hope it is helpful. Of course, if you are also trying to replicate this project, please feel free to comment on any issues you encounter. I will work with you to find solutions.
Recreate the background
Before working on this machine, I had been using the XieGu G90N with a Yaesu FT710 for FT8 communication for some time. Therefore, I particularly needed a device that could be easily carried outdoors and quickly establish FT8 communication. It uses a power bank for power supply and a very convenient antenna.
Coincidence
It was quite a coincidence that when I used workbuddy to search for similar open-source USdx projects, I found this single-band project operating on the 20m band using an Atmega 328P. And it's very simple in terms of hardware. Without hesitation, I immediately started working on it.
Pebble HF official website https://pebblehf.com
The official website has detailed documentation, including 3D-printed enclosure files. Everything is available; what are you waiting for?
Replicated process
As everyone knows, Gerber's Quick PCB service allows you to create three PCBs for free. However, there are some limitations with this service. On the day I received my Quick PCB board, I realized that the 0603 capacitors and resistors were too small, and soldering them was very difficult.
Subsequently, I used Hua Qiu's PCBA and directly assembled the boards, partially soldering and placing components on five sets of boards. This approach could significantly reduce costs, and with Hua Qiu's initial order offering free service, the cost for five boards was approximately RMB 100.
The remaining components, including the crystal oscillators, 328P, amplifier, 74, 5351, and connectors, were all purchased from Taobao.
Sinkhole
The first pitfall was that the LCD1602 simply wouldn't light up, even after flashing a new firmware.
⚠️⚠️⚠️ The temperature of the soldering iron or hot air gun should not exceed 330°C. Each component must be soldered quickly and accurately, ideally within no more than 5 seconds, otherwise, the crystal oscillator is likely to malfunction. 100uH power inductors are also easily damaged by excessive heat.
The observed fault symptoms. If the LCD1602 still shows no display after startup, check the power supply.
If all color blocks on the first line of the LCD1602 are displayed, check the crystal oscillator and the 328P.
The second problem was the "5351 error," so I wrote a dedicated I2C scan program for Pebble HF. This can be used to flash and test when this issue occurs. It can be used to test whether the communication path between the microcontroller and the 5351 is working correctly, and whether the chip's address can be read. Of course, my 5351s were all destroyed by being exposed to 440 degrees of heat and poor soldering techniques.
The third issue is that many BS170s available on Taobao are fake. The definition of "genuine" differs from the original, so you need to install it yourself.
The phenomenon is that when the BS170 is turned on, it generates excessive heat. I recommend purchasing the original BS170 from Ansen.
Testing
In Zhejiang Province, I used the "ZheLiBan" platform to submit my application for setting up a radio station. Since I was using self-built equipment, I could simply select that option. The BH5EJK WeChat account has detailed instructions on the process. After submitting the application, the management department will contact me within a few days and schedule an offline testing appointment. At the same time, they will temporarily reject my application. Once the on-site testing is successful, I resubmit the application, and shortly thereafter, I can obtain a shortwave license. I applied for 5W within the province, so it was very easy to get approved.
Okay, if you also need a radio for passing the 18-month exam (C license). If you frequently use CW, then the Pebble HF will be a very suitable radio. Of course, the communication experience with CW on this radio is the best; the USB sound quality is not as good as that of professional radios. FM and AM are almost useless. However, this is just a shortwave radio with a total cost of around 100 yuan. None of these are disadvantages.
You can think of the Pebble HF as an enhanced version of a shoe. However, it's a low-cost, portable device with adjustable frequencies from 14-14350.
Have fun!
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