January 23, 2018

My Pixie QRP CW transceiver

Last edited: 30.08.2018

A pixie is an imaginary little creature like a fairy. Pixies have pointed ears and wear pointed hats.
elf, fairy, sprite, imp, brownie, puck, leprechaun, hobgoblin, peri

I finally got round to building my Pixie QRP CW transceiver kit. The result is shown in the pictures above and below. The kit was purchased for about € 10 at HAM RADIO 2017 in Friedrichshafen last summer. If you search for it on the various online selling sites you will find it for sale for even lower prices! For about the price of a Big Mac you can be the owner of this neat little transceiver kit, hi.

Traditionally, homebrewing hams have been building QRP transceivers in to "Altoids" type peppermint tins, so I've found this nice Amarelli tin for my Pixie to be placed in.

The Pixie transmits on 7.023 MHz in the 40m band. It also receives on that frequency of course but there's not much filtering and everything within a bandwith of many kHz is heard. I haven't figured out yet how many kHz, but I wouldn't be surprised if it's more than 5 kHz up and down of the receiving frequency. This could be a problem when operating the transceiver when there's a lot of CW activity, and it could mean that a lot of tone filtering has to be done by the brains. Apart from that I'm really surprised by the nice performance of the receiver. Below you can listen to a recording I made of the Pixie reception last weekend when a contest was going on. Listening to the Pixie with small earphones in gives me this nice sensation I got from experimenting with radio receivers when I was a kid.

The transmitter also works. I've been sending some "VVV VVV TEST DE PA7MDJ TEST DE PA7MDJ AR" messages with my Palm Pico paddle on its side using it as a straight key, and I managed to be picked up in Finland by a station of the Reverse Beacon Network (see screenshot below). Not bad considering that my straight-key keying really needs some improvement (some would say that all my keying does, hi). I've measured the output power to be about 250 mW, a little on the low side (specs say it should be 800 mW at 9 V), but I'm not sure if the battery I've been using has been used before or not (it was the only one I had lying around, and I couldn't wait powering up the Pixie).

I will do further experiments and will do a SOTA activation with the Pixie as soon as I've received and finished building the QRPGuys Mini Keyer V2 kit that I have on order. With this electronic keyer I will be able to use my Palm Pico Paddle with the Pixie in the way it's intended to be used, i.e. as a double paddle. The keyer will also add a sidetone; the Pixie doesn't have one (upon key-down it just mutes the receiver).

QRPGuys Mini Keyer V2
A lot can be found about the Pixie transceiver on the internet (Google is your friend!), but I really liked how the pdf-document "How The Pixie Transceiver Works", which can be found here, explains in a simplified way the working of the Pixie. For more about the Pixie, see also my other blog entries on this page.

Addendum  30.08.2018

See also:  www.qsl.net/om3cug/news/pixie_40m.htm. I recently discovered this interesting web page about the Pixie. It's in Czech but the photographs and schematics with CW sidetone and AF filter mods speak for themselves.

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