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Thursday, November 13, 2014

Colin's BITX


With advice and tribal knowledge from N6QW and MeSquares from W1REX, Colin M1BUU, is making excellent progress on his BITX.  I see that he has some territory on the board reserved for a DDS VFO.  That's fine, but here's and idea for Colin and other builders:  Why not build it with the standard VFO first and then add the DDS or Si570 VFO later, perhaps as an external accessory?   That way you get the experience of building an LC VFO -- the full BITX experience. 

Yea, it is hard to imagine Paul M0XPD as a newcomer to the hobby such a short time ago -- he is definitely now in the ranks of the esteemed digital Elmers.   

And yes Colin, we do hope you avoid unwanted oscillations.  Because of Farhan's great design you have a good shot at avoiding this plague.  But be prepared OM.  It happens to the best of us.  A lot.   Stiff upper lip!  Never give in!  

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Hi Bill,
I enjoyed your video about your Arduino experiment. You bet me to it! I'm really looking forward to getting my version of an Arduino powered BITX up and running.
Steady progress is being made, yesterday I added my first bidirectional amplifier to the build. I now have the mic amp, BFO, balanced modulator and first amp completed. I tested the BFO on it's own and got a respectable looking signal out of it and with a good swing below 10MHz.
Next I need to add the crystal filter, second IF amp and mixer. Pete's video will help for the mixer! BTW, I'm using the ver3 schematic but I intend to use the ver1 band pass filter.
I set out building the circuit following the N2CQR layout diagram but I've already run short on space! I do have a good excuse though, my board is smaller than yours (10"x6").
Despite my best intentions, I'm falling back towards old habits of making my circuits physically small. I'm using MeSquares in order to try and force myself to space things out a bit. I do hope that I don't end up with any unwanted coupling!
I must try hard to leave lots of space between the next bits of circuit.
I was listening to SolderSmoke 104 today and Paul M0XPD was introduced as a new ham. Little did we know that Paul would become such a big player!
73, Colin M1BUU

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