inductor

[radium98]

Hello i need some physical , mechanical ,construction help ,regarding some coils,because i miss an LC meter that can measure values with nH nano henry for a transmitter
i need th ewounding details f such coils if possible ,i have tried an online calculator but not work ,so if someone have an lc meter
thanks
coils value are :
85nH
300nH
30nH
50nH
55nH
80nH
160nH

[Shedbuilt]

Most of the online calculators (or the ones I’ve looked at), seem to be based on the same formulae, which I think, are much the same as I used to use by old school means (pen, paper etc). I think some are based on metric, and some imperial measurements though. Unless there’s measurement or conversion error, you should be in the ballpark, but with RF especially, theory is a start point (increasingly with increasing frequency). As frequency increases, and the intentional inductance and capacitances become smaller, the stray inductance and capacitance effects become more significant. Is your oscillator oscillating; if so, can you tell where it’s oscillating (frequency meter pickup loop, reasonably near to the oscillator inductor) ?
Finding out where it’s oscillating; assuming other components and layout are ok, should give you an indication; as to whether the oscillator inductor is in the right ballpark. If you’ve used the same calculator for all the inductors, the accuracy of the other inductors, should be similar to the oscillator inductor.
What does your oscillator inductor look like (dimensions and number of turns) ?

[Electronically]

On your online calculators you should see for the first coil for 85nh is 5 turns. Diameter 4.5mm. Length 6mm or 6.2mm.
18swg used.ive no tried the other coils but thats a starting point if that helps.

Sent from my AMN-LX9 using Tapatalk

[yellowbeard]

That appears to be this yoke :
https://ludens.cl/Electron/fmtx/fmtx.html
There is a picture that you may be able to count the coil turns from - he doesn't give the turns in the text. Also he mentions that the 2SC688 on the diagram is actually a 2SC668.

[radium98]

yes ,thanks yellowbeard ,that transistor maybe swaped by 199 and also i changed the output to 3866 and also the prescaler ,but the coils i stopped in front

[Bton-FM]

When winding P.A. coils does it particularly matter if I use higher gauge wire, will it change the inductance of the coil significantly?

[nrgkits.nz]

There’s are a number of factors that will affect inductors, their inductance, and also the Q. Using thicker wire will definitely change the inductance for the same number of turns with same inside diameter, you can expect less inductance using thicker wire given the other parameters are the same. Also don’t sit them flat against a ground plane or you’ll get a dampening effect resulting in a lower Q.

On my TX boards I have etched away small squares of the top ground plane directly underneath where the output filter inductors sit, I’ve found this improved harmonic suppression also.

Then there’s skin effect, the higher the frequency the more it wants to skip along on the outer edge of the wire, resulting in more heat at high power due to the resistance in the wire - using thicker cable somewhat reduces the resistance and heat.