Our friend Mark MC Nabb KF7NCF, has developed a VFO coil that uses NPO tuning.
Mark has build his Bitx version 3 using the NPO COIL .
The details for making a case and NPO as per Marks calculations is given here:
v The main thing needed will be the aluminum box. Can you obtain square aluminum
tubing? I used 1-3/4" square with 1/8" walls but I think we could go
up to 2 or 2-1/2" without taking up too much space.
tubing? I used 1-3/4" square with 1/8" walls but I think we could go
up to 2 or 2-1/2" without taking up too much space.
v The coil form can be just some plastic tube I had laying around. It could also just be
a paper wrapped in a circle and then coated with varnish, lacquer, or shellac.
a paper wrapped in a circle and then coated with varnish, lacquer, or shellac.
v The shaft could be any 1/4" plastic rod. The carrier and
carrier locator strips will just be 1/4" or so plastic sheet. All
assembly (mounting strips, the ferrite bead, etc) will be done with
hot melt glue.
carrier locator strips will just be 1/4" or so plastic sheet. All
assembly (mounting strips, the ferrite bead, etc) will be done with
hot melt glue.
v We thank Mark for making this design and we may come up with a small kit that may fit
Inside the Bitx Case.
PICTURES OF MARKS BITX WITH NPO VFO
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1 comment:
Hello,
I picked up a bitx20 version 3 kit on ebay. There are four pcbs in the kit. One is a vfo. However, I can not find any information on this pcb. I know it is a Hartley oscillator, it has a 12 to 8 volt regulator, has to words to R1, outcounter, OUT VFO and the transistors are T1,2,3, (euro) and one inductor. Can any point me to a parts list or schematic? Thanks Dave KB1WOD
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