Saturday, April 1, 2017

Homebrew PiHPSDR

Having seen the Apache-labs version of the PIHPSDR I wanted to customise it to fill my needs, so I needed to assemble my own

All the needed information , with the software,  is at John Melton's github site  The hardware shopping list includes. RaspberryPi 3, 7" Official Raspberry Pi LCD,  8 push buttons, 4 rotary encoders, case and power supply.

All the items were mounted in a 12x7x2" aluminium case obtained from Mouser, The display was held in place with plastic channel finishing strips from B&Q.

Front Panel View

Inner View
Initially I used a $30 rotary encoder that I got off ebay, but being designed for attaching to a motor it was a bit big to go in the box. I replaced it with an HP  HRPG-ASCA # 14F which cost $5 off ebay which fitted nicely into the box.

When first built, I used a 5V 3A regulator bolted to the Aluminium case. However this was dissipating around 8.3V at 2A and was too hot too touch. I tried a series of diodes, each with 0.6V drop on the regulator input, but that also got hot.  The regulator was replaced with a DC-DC switching converter from ebay which kept cool. The negative lead of the power supply, and the negative lead of the RPI were both grounded to the case to avoid negative lead voltage drop issues which caused RPI brownouts

I also included a USB soundcard in the box so i could listen to both audio channels when remote from the ANAN. The audio connections were extended to sockets mounted on the Aluminium box. Due to the close spacing of the USB ports on the RPI, and to allow plugging other items into them, the plastic case on the USB soundcard was removed.

The total cost of the homebrew PIHPSDR was around £120