Building a Small Wonder Labs SW+40 CW radio.

[gil]

Another CW kit! That's number seven  ::) What can I say, it's all fun to me. I was lucky to get that one, as it is no longer manufactured. I found an unbuilt kit on the Rock-Mite Yahoo group. The radio is a 40m CW transceiver with a VFO (allowing tuning the frequency) and an output of 2.5W. There is no built-in keyer. I already have a nice Hammond 1590C cast aluminum box for it. I don't know if I'll have enough space to put the batteries inside the box though, since I will be adding a few PCBs in there. If I can, I will use 11x1.2v rechargeable AA cells. I think the digital readout is pretty flat, so it might work. Not sure If I'll have space for the touch keyer as well? My hopes of including a battery indicator, SWR indicator and audio filter/amp plus speaker are just fantasy on my part I think. Something will have to stay out of the box. I think the audio filter/amp and speaker can go in a separate box, because of size, and the speaker holes are a risk for water infiltration. The SWR indicator could be part of a separate tuner box, which might be better at the antenna instead of in the box (less coax losses). I like the idea of having the batteries inside. I plan on using fairly watertight plugs (no audio jack with big holes!).

Tonight I completed about 75% of the circuit board.

Here are the options I want:
- Touch keyer.  http://www.cwtouchkeyer.com/P4.htm
- Digital display. http://qrpkits.com
- Rechargeable batteries.
- SWR indicator. http://qrpkits.com
- Voltage indicator, http://qrpkits.com
- Audio filter/amp. http://newenglandqrp.org/nescaf

I found a mod online about changing the value of C8 to increase the range, but I need to ask a few people about that to make sure. I will be using a ten-turn potentiometer for better precision.

The whole build will be posted here.

Gil.

[raybiker73]

Looking forward to seeing this! My Rock-Mite kit will hopefully arrive this week, and I can get started on it and my SOTA tuner.

[gil]

The SOTA tuner is great, I have one too! I plan on building a second one and put it in a strong cast aluminum box..

Gil.

[gil]

I almost finished the SW+40 PCB tonight. I am missing R24, the 500 Ohm variable resistor, and I want to change the values of some resistors and capacitor. The next step now is to order those parts and build the digital frequency display, which should arrive soon...

Note that I did not use the IC sockets, which for 8-pin ICs I think is a liability I don't need. I have not found out yet if the crystal cases should be grounded, as this is not specified in the manual, but there is a ground pad for it.. The build was very easy and straight forward.

Gil.

[cockpitbob]

Gil,
Can't wait to hear your operating report.  That looks like a nice kit.  I wonder why it was discontinued.  Not being stuck on one frequency like the Rockmite has got to be a big advantage.

[gil]

Dave Benson is supposedly working on a new version... Who knows when that'll come out though...

Gil.

[gil]

Today i assembled the qrpkits.com frequency counter. Most of the parts are surface mounted. Calling them "tiny" is an understatement. I found that the best way is to put a tiny bit of solder on one pad, place the component in place with tweezers hold it down and melt the solder. Soldering the remaining pins then is easy.





Gil.

[gil]

One up for grabs: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=181004550433

[Randy]

Hey Gil ---

Looks as if you're making good progress.  Keep at it.

Randy  K4LJA

[gil]

Thanks Randy, glad you found the site  :)

Gil.

[gil]

http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=140877277712

[gil]

The SW+40 is finished! Well, sort of... It does receive fine, but does not transmit and there is no sidetone. I received some troubleshooting tips from Dave Benson the designer, so it shouldn't be a big deal to fix. In the mean time, I completed a small audio amp for it, and received the touch keyer (see photo attached below). So, there are four circuit boards I will add to the main one: The digital display, audio amp, touch keyer and battery indicator, which I haven't built yet. Hopefully there will be enough space in the box, or I will have to use a different one. Each option will have a separate on/off switch to save batteries when needed.

The new audio amp is not the one I mentioned previously, with a filter. Since the SW+ has a 400Hz filter built-in, I decided not to use the Nescaf one, but a smaller, filterless model: http://rainbowkits.com/kits/ap-1Wp.html. I will use the filter for another project, a battery/filter/amp/speaker all-in-one box for my Rock-Mites.

So, my next step is to fix the SW+40 transmitter section, then box it up with the chosen options, and if possible, batteries.

Stay tuned  :)

Gil.

[Lamewolf]

I have some mods listed for the SW series rigs on my website at: www.angelfire.com/electronic2/qrp