Sunday, June 23, 2013

Knobless Wonder build

Over the past few weekends I've been building VK3YE's "Knobless wonder" a fixed frequency SSB transceiver for 40m. It's at the point of starting to work, although transmit sound is very poor right now.

A scan of the circuit is here. I've enjoyed the build, it's simple enough for me and I was careful to build and test stage by stage, stopping if something didn't work and figuring it out before going on. The main thing that goes wrong for me, aside from failure to follow the circuit accurately, is that sometimes I have mis-filed components that I grab without checking.

The technique I've used is "Manhattan" ugly construction using snap off squares I purchased on-line and super-glued to the base boards. This turns out pretty neatly and makes the board look like the circuit diagram so it's easy to debug.

So far the receiver seems pretty deaf, although it hears my shack oscillator sweeping quite well. The transmitter has been heard by VK2BMS a few Km away although the audio is not good at this stage. I think the oscillator isn't tuned correctly yet - I need to figure out the best way to adjust this.

My thanks to Peter for a nice design that is easy to reproduce. I think this is a great group project for people who live pretty close together.

1 comment:

Anonymous said...

You might be interested in some circuits I have here:
I think the best regenerative circuit to build is the one on the Q Multiplier page and maybe the second best is the TriStar design.
The web-page is in my wife's name.
There is also a book I wrote on regenerative receivers that at least points out all the main design factors to be considered (many!). You will have to dig around on the to find the link.