Projects

80m Filter

I’ve been working on a direct conversion receiver, on and off (mainly off with a couple of spurts) for a few months now based on a talk by ‘Nick the Vic’ M0NTV, and I recently put together the 80m filter. It’s designed to be modular which is quite nice because it does mean that I can dip in and out. I’m going to put together a writeup of what I’ve done, but for now a couple of pictures.

You can see in the first picture that I’m using a ‘mint tin solder pads’ PCB which I purchased from Kanga UK, very convenient for using with my mint tin, I’ve found it great and on the reverse side it has the same but with split pads.

Not pretty, I’m going to try to get some bulkhead SMA sockets for next time.

Auto ATU back home

After my latest adventures with my Auto ATU and adding a jumper wire I was having some odd behaviour so a club member Dave G8KBB offered to take a look and give me a second (and far more experienced) opinion.

It turns out I somehow jumpered the wrong trace and there was also a soldered end of wire which wasn’t cut short enough and was therefore prone to short out, silly things as usual! Dave has jumpered the other trace, cut short the wire and advised that I box it up ASAP and add a fuse to the power cable.

Many thanks to Dave for the assistance and advice!

Audio Amplifier Working

Finally got the audio amplifier working, there are still some tweaks required but almost there. In the end I eventually discovered that I’d somehow killed the LM386 chip, so I replaced it, but second time round used an IC holder then slid the chip in, not making the same mistake twice!! After all of the resoldering as I disconnected and reconnected wires and components to find the issues it’s not looking pretty.

Audio Amplifier On Perfboard

Finally got round to moving the audio amplifier project on to perfboard. I actually wanted to use stripboard, but TWICE managed to order the wrong thing somehow! I really haven’t enjoyed using perfboard, I’ve been using wire-wrapping wire and have found the whole process incredible faffy and fiddly. I’ve been using small pieces of wire and offcuts of components to connect between the holes, but that again is really faffy. I’ll probably end up using perfboard again as I’ve bought a few, but wish I’d bought the stripboad.

I’m having real issues getting this to work, I’ve got very quiet audio and a lot of crackling. I’m working through the various issues at the moment, nothing like a bit of problem solving!

Audio Amplifier

This is the second module I’ve built for a direct conversion receiver based on a talk by ‘Nick the Vic’ M0NTV, it’s an audio amplifier using the LM386 chip. I decided to prototype it on breadboard and have investigated various configurations using the chip which has been a great learning experience, once I settle on a final configuration I’ll transfer it to perfboard and put it together using the potentiometers.

Oops, zapped my Auto ATU!

As I’ve documented on this website I have recently put together an Auto ATU 100 kit. The ATU works well and I’ve bought a metal case but the buttons that came with the kit aren’t great and I’ve not put the time in to cut out the case. For the time being I have been using the ATU on a plastic tupperware lid, however I’ve also been using Dupont wires and croc clips to connect to my power supply which has led to some unfortunate incidents with disconnected wires shorting to ground, in the latest incident I have unfortunately fried a small region of trace.

Everything seems to work fine, however I’m going to add a small jumper wire to replace this trace as it looks fairly dodgy. I’m hoping that I haven’t fried any components but I think I’ll have to add the two optional extra buttons to allow me to use some of the debugging features.

Colpitts Oscillator

Quite a while a go I undertook a small project to build the Colpitts oscillator found in the RSGB intermediate book (purchased as a kit from Jab Electronic Components), despite putting it together as per the schematic I couldn’t get it to work. With help over email and zoom from Jack G3JIR and some other club members and after eventually replacing pretty much all of the parts with spares (many posted from helpful club members) and reassembling on a breadboard, hurrah I got it working!

I think that in the end it was the transistor being incorrectly wired which was the issue, despite having checked and double checked…or so I thought, but it was a long and painful process to debug, quite a learning curve as a newbie in electronics.

Finally the illusive output from the oscillator!