MAS-80 Minimal Parts Count Transceiver

This rig was designed by Steve Weber, KD1JV, to meet the challenge of a minimal parts count transceiver to be used in the Minimal Art Session (MAS) Contest which is held annually on Ascension Day. See more on the contest below.

The rig can be built with as few as 51 parts, and performs quite well. It utilizes a regen receiver, 2 transistor MOPA transmitter, and is an innovative design with T/R switching and muting circuits. Operation is very smooth, with excellent keying and good receiver sensitivity. At this time there are only 3 in existence, Steve's prototype of course, and both Seab Lyon, AA1MY, and myself have one.

Mine is scratch built from the information on Steve's MAS-80 web page . To make the board I used an iron on process that I call Easy PCBs. This is the first time I've used this proceess and the board came out nearly perfect. The component side of the board below is a label, much like the others I've made, except I sprayed it with clear acrylic before application. I suggest attaching a frequency counter to the junction of Q10 and R10. This will facilitate the initial receiver tuning adjustments. Here are the results of my build.

Seab's rig makes about 3W, and Steve indcates that ~2W can be expected. Mine only puts out a little over 1 watt, so further work wth the LPF inductors I wound is in order for me. How does Steve coax a coupla watts out of a single 2N7000 final? He explains it on his web page, but he must be part magician too.

If you are interested in working the MAS contest, I suggest that you build this rig, and forget the Pixies, Gnats, etc. This one really works, and requires no tinkering after assembly. Mine worked well immediately upon power up.. Even if you're not interested in working the contest next year, try this little rig. It's a great building experience and a lot of fun to operate.

The MAS contest was on May 21rst of this year (2009), and will next occur on Thursday, May 13, 2010. To quote from the rules " the QRP-Minimal Art-Session (MAS) at Ascension Day is an eye-winking challenge to make qso with rigs as simple as possible. You are invited to prepare your participation with a TRX (resp. TX & RX) out of not more than 100 components (Class A) or a TX out of not more than 50 comp.(Class B)."

Here are links for more information:
The German QRP Contest Club, QRPCC, who, under the leadership of Dr. Hartmut (Hal) Weber, DJ7ST (SK), created the MAS Contest.
MAS contest Rules on the QRPCC Web Site
A QRPedia posting inviting US hams for the first time.
Ascension Day in the US.
Ascension Day in Germany.

If you build this neat little rig, I'm sure you will enjoy it . WAĜITP Revised 27November2012

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