Sunday, 12 July 2015

Frog complete, ready to test

 Carrying on with the Chinese 'Frog Sounds' CW transceiver build. Finding a bit more spare time, the next stage was to fit the capacitors

With these installed, I moved onto the semiconductors, and the rest of the parts.

 At this stage it was all but complete. The only parts not installed being L4 and L5. Ive left a little clearance above the PCB for the crystals, which I would normally install flush to prevent microphony, but the solder pads on the component side of the board looked a bit wider than the insulation around the pins, so I didnt want to risk them shorting out.

L4 and L5 proved to be a little more problematic. The paperwork that came with the unit states that these are 1uH and 22uH, but neglects to say how many turns, and which is which core! Thanks to members of the G-QRP club, and in particular Andy Cutland, I found out they are 11t on the ferrite toroid for L4 and 16t on the T37-2 toroid for L5.

A word of warning for those of you building one of these and used to the easy life of the western coil winder - the wire supplied is NOT self fluxing! I had to scrape of the enamel which is a delicate job. But, the coils are now wound and installed. All that remains is to test the unit.

As usual, it seems, with these Chinese Kits, Ive a lot of 'spare' parts left over! Lots of extra resistors, ceramic capacitors, probably three extra lots of the electrolytics! Plus the odd diode and a 2N7000 MOSFET. I notice its never the NE602s the put extra of in!

 Back to the subject of LASERs! -

I have on order a pack of ten 1mW 650nm Red laser modules. Well, I now also have a project for them! Im going to knock up a simple voice transmission link with them. Using a 555 timer and some op-amps and comparitors, it seems i should be able to use PWM (Pulse Width Modulation) at 40kHz, to create an amplitude modulated laser voice link.

My green laser pen that fell to bits I dismantled. Unfortunately, although the big brass block acts as a heatsink, this makes it hard to solder a wire to, and in doing so I over heated the module. The laser chip is fine - but I melted the plastic lens in the laser diode housing! It still works, but the beam is a tad divergent now!

1 comment:

TJC said...

Thanks, Zak.
I've been trying to figure out how many turns to use on those toroids. Now maybe I can get it to do something meaningful.