Friday, October 16, 2020

Micro Mountaineer 40m Xtal locked CW transceiver review

I've just completed a build of a kit I haven't seen before. The Micro Mountaineer is a crystal locked 40m CW transceiver that is a step up from the widespread Pixie kits that you see on Ebay.

I purchased mine for AU$20 from AliExpress here. It came with crystals for 7023kHz (it uses one as an oscillator and the other as a bandpass filter).

The printed instructions appear to have been machine translated. Presumably from English to Chinese and then back again. Documentation is therefore a bit strange but understandable.

The circuit is credited to W7ZOI (he mentions it here) and K7TAU. The design is an NE602 mixer and LM386 audio stage. Receiver is based on the Neophyte design.

The original description and circuit is in the wayback machine here.

My kit arrived with a tiny surface mount LM386 and a little carrier board but happily I have full sized chips in the junk box so I used one of those.

There's no keyer circuit so this would be easy to use with Feld Hellschreiber mode - a great trick for those of us who have failed to learn morse but like the simplicity of these CW rigs.

The waveform doesn't look great. (This is via a 10x probe). Getting about 1W into 50 ohms.

I enjoyed building the kit and it was good practice before I take on the uSDX when the board arrives. All parts were supplied and even some extra passive components were added. It's a pity the supplied LM386 was surface mount but the carrier board would work - I guess it's a sign of the times that full sized through-hole components are getting harder to find.

After several months, the TinySA arrived. Initial impression is good.


  1. Credit should go to W7ZOI, not ZOL. More info about this design can be found on his website.

  2. Thanks John, updated. Of course! I should have realised that. Unfortunately his page about it is no longer up. I will try to find it in the internet archive and link to it.

  3. Just finished a build , very low power output , did you ground the crystals ? What voltage are you running it on ??

  4. Bill, it would have been 13.8V