Building The Small Wonder Labs SW40+


I had a few extra minutes today to hook up the pots and the power. The battery is 12v 7ah. There is a 1 watt audio amp (Rainbow Kits) connected to the audio output, as I wanted to be able to listen through a speaker. The temporary antenna is an indoor 20 meter dipole. This was connected only for the smoke test. I will attach the G5RV when I get ready to align the radio.

Ready for smoke test - fingers crossed!

Here is the 1 watt audio amp – a very simple and inexpensive ($7) kit. Here is the url for the kit:

1 Watt Amp

You might have noticed that the main tuning pot is not your usual potentiometer. It is a 10 turn pot, which spreads out the tuning a lot. They are expensive, I have seen them for as much as $30. I bought this one on eBay, for $7.89, which includes shipping from Taiwan! It also took only 11 days to get to my door – not bad.

Note: If you use one of these 10 turn pots, be sure to check the pin-out. It is different from your average pot. On this one, 1 is in the middle.

50K 10 turn pot for $7.89 works great!

With everything hooked up, it was time for the initial smoke test. It was better than I had hoped. First, there was no smoke. Even better, I immediately heard several signals on the band. Not bad considering the receiver has not yet been aligned, and it is hooked up to an indoor 20 meter dipole.

Clicking on the link below will open a 1 minute video of the initial smoke test. It will also give you an idea of how the 10 turn pot spreads out the tuning.

SW40+ Smoke Test

Leave a Reply