Weekend Project – Polyvaricon Tuned Sudden
Receiver
Spent sometime these last few days building up the G3RJV Polyvaricon
Tuned Sudden Receiver. The idea came from a Christmas gift that Doug,
KI6DS, presented to the attending members of the NorCal Dec 2006
meeting. You can see the article at
http://theqrper.blogspot.com/2008/10/christmas-past-sudden-holiday-surprise.html.
I had one problem after laying the circuit out…the internal oscillator
in the NE602 (you can also use a SA612), pins 6 and 7, would not start
to provide the LO for the mixer. Turns out I tried to take a shortcut
and only wind three turns on a ferrite core instead of 31 turns on a
iron powder core roid to make up the L/C circuit. Using ferrite for a
oscillator is not a good idea as the circuit Q will be lousy and not
work at all. I listened to 40 meters this afternoon after my
grandkids headed back to IL and I really like the sound of this
receiver. I may have to do some more direct conversion receivers just
to get a really good feel for them.
My thanks to the fine folks on the qrp-l.org mail reflector! They
always seem to be there to help out with suggestions and advice! Lots
of collective and sound grey material on that reflector.
