Friday, October 31, 2008

Tips for getting your Bitx working

If you have build your Bitx and are not being able to receive or transmit with a very low power then I have some solutions that may be of help.
BFO tunning problem- Many of us are faced with the problem of adjusting the bfo to the correct frequency so that it is in the pass band of the filter. A simple way of getting the frequency would be to use a 10uh rf choke in L5 and 22pf capacitor with it.
This combination worked for me in several bitx I made. After the set is working you could wind the necessary turns to get 10uh, the rf choke will pick up broadcast so finally you should remove it.

The second cause for the receiver not working would be that your bandpass filter is not tuned. If you use 47 pf see that the bandpass coil slugs are tuned on the top of the coil,once you get the signals with connecting the antenna you could further tune them up or down according to the maximum signal strength.If you use 33pf it should tune somewhere in middle of the coil.

A problem that has been bugging some is the low output from the Bitx main board,so the linear does not give sufficient output, it maybe be as the IRF is not getting the sufficient drive and so a low output.
I found a interesting circuit in sprat sent and recommended by my friend Tony in U.K
A bsx transistor stage could be coupled to the 2n3866 in driver stage on Bitx version 3 linear and an increased output may be possible, i have not tried it out as yet but maybe guys having a problem with low output may try this mod.

The Bitx version 3 will now be easier to make with the manual by Leonard and all the help from Bitx forum members.
If correct procedures are followed then Bitx version 3 could be a quite easy to build,but sometimes due to some mistakes it sits around looking for further attention. hi hi.
Best Regards

Circuit For Increasing the driver output in Linear take from Sprat Magazine.

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