Re: Compressing or expanding turns on a toroid.


geoff M0ORE
 

The late W4ZCB described a simple L & C oscillator to which you added the un-known component and then measure the frequency and by using a simple bit of maths or a spreadsheet calculate the un-known parameter. You needed a good reference capacitor to do the initial calibration, I was lucky to be able to borrow a 0.1% tolerance to make my own standard. Not perhaps  as good as a lab standard but I am aware of the limitations.

On 12/09/2020 23:53, wb8yyy via groups.io wrote:
Yes nice explanation that physical arrangement of the coil adjusts inductance.

One can measure inductance by resonating with a capacitor, measuring frequency,  and calculating inductance from that. Here in US the njqrp once offered a little kit that measured inductance and capacitance, in era before cheap lcd. Read them out in morse. I don't know what's out there now, but an LC meter would be a nifty offering,  yeah take advantage of a market here too focused on their coils.

73 curt

Join QRPLabs@groups.io to automatically receive all group messages.