Micro80 QRP transceiver

This must date back about 40 years! Looking through some old photos, I came across this one of my 80m Micro80 transceiver. 

As I recall my first contact was with a station about 200 miles away and before it was cased and the Morse key was just tapping a wire onto the chassis!

I cannot recall the antenna.

Pixies and Micro80 transceivers

At one time you could buy Pixies kits for 40m CW very cheaply from China with free airfare. It may still be possible. 

The Pixie transceiver was derived from the Micro80. Both have severe limitations, especially on RX. Nonetheless, they work and can be a very low cost introduction to the hobby. I have built both in the past.

You may be amazed that something this simple actually works.

Pixie transceivers

The Pixie is a classic low cost CW transceiver usually for 80m or 40m. It started life as the Micro80. Kits are available from China at ridiculously low prices, although some are better than others. 

It uses the PA transistor as a mixer and often suffered from poor selectivity and AM breakthrough. It was let down by this poor RX. Over the years several versions have been created to help with these issues. 

However, it does work and is capable of really get contacts.

The photos show a typical Pixie and my version of the Micro80. 

See  https://sites.google.com/view/g3xbm4/home/hf-mf-and-lf/homebrew/8040m-pixie-and-micro80-transceivers .

Pixie and Micro80

There has always been challenge to get the most from the least. We will happily pay well over £1000 on a new rig, yet we often get more fun from a rig costing just a few pounds to make. 

One such is the Pixie or the Micro80. These are compromise rigs, often let down by the RX, which tends to be the weak link. They work and I have had QSOs on 80m and 40m with mine. At one time you could buy 40m Pixie kits from China for a few pounds. I bought one of these and it went together well and worked. I have not looked recently to see if these are still available. With the Pixie and Micro80 I am afraid of calling CQ over a weak station.

There are other rig alternatives although with something simple, you usually have to accept some weakness. The "holy grail" is a simple, low cost rig that really is not a compromise. If you know of any, let me know. My target is a complete transceiver that can be made for less than £5 that really works without compromise.

See https://sites.google.com/view/g3xbm4/home/hf-mf-and-lf/homebrew/8040m-pixie-and-micro80-transceivers .

Pixie and Micro 80

These little QRP transceivers first made an appearance some 20 odd years ago. They are extremely simple transceivers that use the TX PA as the RX mixer to save parts.

I built a Micro 80 some years ago and my best QSO was around 300km.  Biggest issue (for me) was broadcast breakthrough from strong broadcasters just above the 80m band. Variations included the Pixie 2 which added some refinements at the expense of more parts. Kits are available, but the circuits are so simple it is not work paying over the odds for these. The Micro 80 uses all discrete components whereas the Pixie and Pixie 2 use an LM386 for the RX audio.

If you build one, be prepared to fight for contacts. It is not the TX power that is the problem: it is the receiver that is the limitation.Given good conditions and little broadcast breakthrough, these rigs work.

See https://sites.google.com/site/g3xbmqrp3/hf/pixie .

The same basic schematic will work on any HF band with changes to the output filter. Watch out for chirp on the higher HF bands: don't be tempted to try to pull the crystal too much, especially on the higher HF bands.

Micro80 4-transistor transceiver QSO

After some time without use, I resurrected the little Micro80 4 transistor transceiver for 80m last weekend. To increase the power a bit I've now got provision to run it from an external gell cell battery at 12v, so giving me about 2dB more RF out compared with the 9V internal pack. Using it with the bench PSU was impossible because of 50Hz hum pick-up. I also managed to improve the AM breakthrough by around 10dB at least by putting a 4n7 cap across the base-emitter junction of the first stage of the darlington in the RX AF. This makes it a usable radio on 80m at night now as it is not obliterated by the BC stations around 4MHz. Success soon followed with a solid QSO with G3XIZ in Biggleswade around 30 miles away late Sunday afternoon.