A small 40m transceiver using surface mount components!
Many people have been mentioning that they would love to see a “training” or “beginner rig” before they tackled a new full-featured SMT-based rig which will not be available until early fall. I thought about this, talked with Dave Fifield, and together we came up with a unique kit … the SMK-1.
What is the SMK-1?
Well, it is basically the TT2/MRX with Mods circuit that is on Dave’s webpage, but we had to make some changes. First of all, the LM380 is not available in surface mount, so Dave switched it for an LM386. What he ended up with is a neat little surface mount project. It is a transceiver, with separate VXO tuning for transmit and receive. That means you have instant RIT and XIT!! Plus, it uses diode switching, and has a real side tone!! Neat huh? The transmitter tunes about 1 to 1.5 kHz, and the receiver about 4 to 5 kHz. and they overlap, so true transceiver operation is possible. No thump, but a slight bit of chirp, nothing that is horrible, just there. No microphonics. We use the MRX receiver circuit with a couple of mods, and it works pretty good. The prototype has an mds of about -117dB, which is fine on 40 meters.
The exciting thing is the rig is all surface mount parts except for the 2 crystals (7.040), two trim caps, and the 3 control pots. We use 1206 parts, the “big ones”. 1206 means that they are .12 x .06 inches in size. There are 85 parts in the kit, a professional quality, double sided, solder masked, silkscreened board, and we supply all board mounted parts including the 3 control pots. You will need to come up with the audio jack, key jack, power jack and antenna jack of your choice. The 3 control pots are mounted across the front of the board, and are used to connect it to the front panel. The pads for the audio, key, power and antenna connectors are on .1″ centers so you can use molex connectors if you wish (not supplied). We are not supplying a case, but, our good friends at the NJ QRP Club are doing a specially designed case kit that comes with the connectors, knobs and feet. George Heron will be posting the details soon, including where to see a picture of the case.
I have saved the best for last. The size of the board is 2.5″ wide by 2.25″ deep!!
This is a very usable transceiver. It is not a NorCal 40 or NorCal 20, but it is better than the 49er. The prototype puts out 360mW, and Dave made the first qso last night with Ed Loranger, WE6W. It was not staged or set up. Dave called CQ, Ed answered and they had a nice long qso. This rig is designed to introduce you to working with surface mount parts. It has over 70 surface mount parts. We think that the average builder will not have a problem with it. We did this to start training qrp homebrewers in SM construction. We also wanted to do a simpler kit that would be very easy to build, provide training, easy to trouble shoot, and also give me experience kitting before the full featured rig comes out. Parts will be ordered this week, and I anticipate shipping to begin in less than a month!! I have some unique ideas on how to package the parts so that they are easily identifiable yet reasonible to kit. Should be fun learning together.