On 29/11/2017 6:04 PM, chuck adams wrote:
Have you put them into a VFO to test their temp coefficient?
Hopefully you have a datasheet to share with the group.
Farhan used the same trimmer in the analogue vfo version of the BITX40. If you changed the fixed capacitors for good NP0, it was quite good but in my opinion the inductor stability is much more important.
I don't usually use toroids in vfo's. It's difficult to wind and get the winding taught. In the old days we used to say put the coil former in the fridge and the wire in the oven and then wind the coil as tightly as possible. That with polystyrene caps made a stable 23MHz vfo.
I am interested to see what I can achieve with my NC40 build. I only have 6 material for the core. Hand winding a vfo for 2.1MHz on a straight former is of course much more difficult than at 23 MHz.
I add my thanks to Hans for making them available.
73 Brian VK4BAP
