Monthly Archives: February 2014

Easier Upgrade

Now the mcHF has device bootloader, Windows upgrade utility and much faster and easier way to upgrade its firmware. The DFU procedure with shorting the P6 jumper is still needed, but only on the initial blank programming of the ST32F4 CPU. After that every new firmware version is installed via USB cable only and the mcHFManager Windows utility

bootu3

All details and download in the Software page (use the drop down menu)

TR switch with PIN diodes

I have abandoned my plans to use MMIC chip switches, they seems too fragile for HF. A simple RX protection circuit attached to the PA output protects the BPF input switch from high energy. Series and shunt PIN diodes are used, controlled via a pair of PTT/PTT_NOT signals.

sw_sch

So far this configuration can handle 5W safely.  If more massive overheating on D1 occurs a blob of solder acts as primitive heatsink on the prototype board,

pin_sw

LPF & PA test

It is time to test the LPF switching and response, together with the final amplifier attached. It is quite a messy setup, the whole proto concept is getting more and more cluttered.

lpf_testClick for large view