zondag 30 juni 2013

Bitx20 V3 "Dead Bug Style" Test stage.

May I present to you,my "Dead Bug Style" Bitx20 V3 in working order.The finished PA-Amplifier from the last blog is now connected via RG174 coaxial cable to the exciter board.I added a front and a back from copper board.In the front you see the volume and fine tune potentiometers.The main tune is from an old radio.The S-meter is not working yet,I have to build another circuit for that.The Amplifier does about 1,5Watt when my power supply deliveres 13,5Volts DC.On the back I mounted a PL259 socket for the antenna and a cinch plug for the speaker.Are we finished now,unfortunately, no.There is a problem.I first discovered that when I was only listenging on the band.It seems that the further I went up in freqency,the more deaf my Bitx sounds.I had to adjust my bandfilter slightly.As I mentioned,my Bitx does 1,5Watts,but only in the range of the bandfilter where it`s not deaf.Under and above that "deaf" frequency,there`s now output on the Bitx.It seems that the bandfilter is only 80KHz wide.That`s not enough,it must cover the whole 350KHz.(14,000MHz-14,350MHz).So there`s work to be done.I think that when I solve the issue with the bandfilter,I automaticly have solved the problem with the output of the PA-Amplifier.
(bron:PI4RAZ)

This is the bandfilter I`ve used for the Bitx20.The bandfilter was originaly posted on the PI4RAZ site.They build it years ago with a bunch of OM`s .Only they used a IF of 11MHz.I don`t think that the IF of 10MHz I used,can cause this problem.Maybe when all my aforts to correct this problem doesn`t solve anything,I can alway`s post a question on there site.OK,on the pictures bellow you see the Bitx20 V3 at this moment.Hope a can fix the bandfilter soon,because all the components for the Multiband Bitx are in the house.Can you imagine that,a homebrew tranceiver from 10 to 160 meter with a DDS VFO with the firmware of PA0KLT and 20Watts output.I cant`t wait to start with that project.You can take a look at the site of Andy,I think he don`t mind the link.Multiband Bitx

If you take a good look at the bandfilter,you see that I already did some experiments on the trimmers and the 82pf capacitors.They are not as nice alligned as the original parts on the bandfilter.

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