1 Dec 2012

The first Tenbox Schematic

The breadboarding of the Tenbox 10m AM transceiver for local cross-town night-time nattering is almost complete now, with just a receiver audio amplifier to drive a loudspeaker to be added. Power output is a conservative 250mW AM carrier (peak power around 1W).  The first schematic draft is shown here, but as always I warn that I may have forgotten to correctly label some parts and the values may change as the circuit is further developed. I hope to road test this over the weekend going out in the car with a mag-mount antenna whilst AM beaconing with the rig from home. As with WISPY, I have paralleled up 4 2N3904 transistors for the PA. This is a very inexpensive way of making a 10m PA stage! The alternative, such as a 2N3866 would be about 5-10 times more expensive.


Rifleman said...

V interesting PA stage, Roger - I don't think I've seen that done before with transistors, though I have seen examples of PA valves in parallel - but only two, not four!
And a very clear cct diagram, too. May I ask what software you use for it, please?
Best regards,
Jack Enright M0DZM

Roger G3XBM said...

Jack thank you. I use s-Plan software available from http://www.abacom-online.de/uk/html/splan.html. It is extremely easy to use.