I was lucky enough to score one the 150 units of the Mountain Topper Radio v2 (MTR 2) that Steve Weber KD1JV produced earlier this year (2014). This is a fabulously compact CW transceiver that covers three bands (in my case 40/30/20m) and provides 5W output.
For SOTA activations, you can’t get much more compact. It operates happily on a 500mAh LiPo battery for a couple of activations and weighs next to nothing. The only accessories required are earphones, an antenna and a paddle.
As you can see from the photo, everything except the antenna and paddle fit in a 2.5″ hard drive protective case. The paddle was the component that potentially was hardest to pack and also secure to something solid to operate from in the field. Reading the AT-Sprint Yahoo group, I found that a few users had built in touch paddles to this and similar radios. It struck me as a good option to further simplify the arrangement. I also saw that a very compact touch paddle board had been produced in the Czech Republic by hamshop.cz. Here’s the link to the actual product: Touch Paddle. This made adding a touch paddle a very simple mod for the MTR 2. The module is secured with double sided tape to the bottom of the case.
The touch contacts are fashioned from a 5mm x 8mm pan head stainless steel screw and matching dome nut (obtained from eBay: Fastner Kits Online.) They are insulated from the case with a piece of plain PCB with two copper squares making up connections to the screw heads. There are also small nylon bushings where the screws pass through the case (made from a simple nylon PCB spacer) and a nylon washer under the dome nuts.
The board is connected to the main transceiver PCB with two twisted pairs to minimise RF pickup into the paddle board. The board only needs 3V to operate, so it is connected to the 3.3V supply at the oscillator module. The output simply parallels the paddle jack contacts. The only addition I made to the module was to add an additional 0.47uF ceramic capacitor across the power supply input to the board to provide a little additional RF filtering (I don’t know if this was necessary, but hasn’t harmed anything).
The touch key works really well and is quite easy to use. The only thing you need to be careful of is not to brush against the contacts when moving the radio with the power on. It is important to discipline yourself against switching on the power unless an antenna is connected for this reason.