HX108-2 7 Transistor AM Radio Kit - Power Supply 

Links:

• HX108-2 English Documentation - Improved 
• YouTube Page of Chuck Adams, K7QO

On K7QO YouTube page scroll down to the heading: 
Chuck Adams RF Receiver Course on YouTube
find links: 
K7QO HX108-2 AM Receiver: Theory and Construction - Part 01 to 
K7QO HX108-2 AM Receiver: Theory and Construction - Part 09. 
If you watch and follow along "You might learn something" as Chuck K7QO said.

Part 01  HX108-2 Introduction and Power Supply 

Unboxing and parts inventory - Kit has all discrete electronic components, to be mounted on a thru hole PCB. No IC's, no SMT/SMD parts, but also no assembly instructions. (Not your Dad's Heathkit...) 

You do get a single sheet that combines the schematic, parts list, PCB diagram, resistor color code, capacitor code, transistor pinout, specifications and soldering instructions that are all in Chinese. 

The schematic has a few errors and there have been instances where the transistors were substituted with other transistors having a different pinout.

For all these reason this kit is not recommended for a novice kit builder without an Elmer.  

The Chinese documentation included in my kit purchased in March 2019 was dated 2018.8.6 The PCB is marked 20110518 which I assume is the PCB version date. 

Part 1- Power Supply

 Got the schematic with the power supply circuit highlighted.  I also place the small electronic components in the edge of strips of corrugated cardboard that I pasted a section from a copy of the parts list. Idea was from Randy - K7AGE from one of his YouTube Videos.

A cluttered bench is a happy bench

 I started assembly of the case. I installed the speaker, battery terminals and the front faceplate. I had to use super glue to keep the long spring wire terminal in its slot when the AA cells are put in.
I also placed the thumbwheel and screw on the shaft of the volume control W and marked a line that would point to 7 o'clock position when K is off (open).

On the PCB I used a 15W soldering iron, 60/40 solder and a liquid rosin flux pen. Soldering to the PCB was good with only a few joints requiring reflow.  One difficultly was the supplied wire for the power leads were smaller than 24 gauge (smallest setting on my wire stripper). I used an X-acto knife to trim the insulation back so I would use jumper leads between the case and the wire leads soldered to the PCB.

Test Data Measurements: 

• Voltage across battery terminals = 3.2Vdc
• Voltage from anode D1 to Ground = 1.45Vdc K=on / 0.0Vdc K=off
• Voltage from anode D2 to Ground = 0.72Vdc K=on / 0.0Vdc K=off 

Test data measured was the expected results. Part 1 of the build was successfully completed.
In Part 3 we will solder the components that comprise the AUDIO sections.

(Part 2, Chuck Adams K7QO suggests some of the test equipment you may wish to use.  Including some cheap Chinese kits available of eBay.)

73, AB1OP Ralph