Micro Build Report: QRPMe Tuna Topper
Sometime in 2023 I’ve purchased a couple of ham radio related building kits (Tuna Tunah, Two Tinned Tunas, Tuna Helper, Sudden Storm) from QRPme, a ham radio kit web shop run by OM Rex Harper, W1REX. One of those building kits is called Tuna Topper. The Tuna Topper is a RF amplifier that boosts your signal to a full 5W at 40 m. It’s a well made little kit with a detailed assembly instruction manual – however it’s assembly can – in difference to all the other kits – become a little tricky. Below you can find a couple of images from the build process:
Caveats
High configurability -> complex assembly : The Tuna Topper is highly configurable: you can choose between fast or slow transmit/receive switching, working with separate receiver and transmitter or a combined transceiver, using the Tuna-typical RCA connectors or your own RF connectors, use an optional attenuator for reducing the power of a too-high incoming RF signal. This configurability comes with an added complexity during the assembly process. You need solder jumpers and wire bridges as well as mounting components at different locations (or not mounting components at all). The manual needs to be perused carefully so as not to overlook something.
Non-ideal usage of available space: The complete RF amplifier circuit is made to fit into a rectangle that’s a part of the round standard Tuna PCB. The reason for this is that the same PCB without „wings“ is also sold for direct integration in your own QRP projects. This leads to the board being unnecessarily cramped and many components need to be mounted vertically – which is not as easy to do in an astethic pleasing way as if they are mounted flash with the PCBs surface.
Toroids: Some people love winding toroids, some hate it (mostly because they fear screwing it up). I am coming to love it, but even I made the mistake of using the 26 AWG (instead of 20 AWG) for the output filter toroids. When I was about wind the input toroid at 26 AWG I noticed that I am bit short of material. Fortunately I could re-supply from my own isolated wire collection.
Resources
TT-Assembly-Manual (25 downloads )Happy building 😉