Hi all,

I need to make an air core 16 AWG inductor with 8 turns. If I convert the AWG size to metric I get 1.29mm - I am struggling to find that, I have wire that is 1mm, is there a way I can determine how many turns I would need of that to have an equivalent inductor to match the spec of 8T 16 AWG?

The specs are:
16# (which I presume means AWG), 8 turns, length 0.625 inches, inner diameter 0.135 inches

 

Hello,

Can you find 1.2 mm wire?
That should be close enough.
Even with 1 mm it still should work (it is probably in a tuned circuit with a capacitor that can be adjusted).

Here is a page in air coil calculations:
http://info.ee.surrey.ac.uk/Workshop/advice/coils/air_coils.html

This is a link from the EDUCYPEDIA on coils and toroids:
Coils

Bertus

 

Hi Bertus,

I will see if I can find 1.2 mm - yes, it can be tuned with a variable capacitor.

Thank you for the links.

 

I found 1.25mm diameter wire, so problem solved!

My other problem is that the circuit calls for a silver mica capacitor. I've read up, being a beginner in this field, and found that silver mica is used because of it's high stability in RF circuits. However, would it make that much of a difference if I used a ceramic NPO capacitor? The value needed is 4.7pF - I have a ceramic NPO cap in that value.

The circuit is for a small tracking transmitter, not very high output.

I ask because I am having a very hard time finding the silver mica capacitor.

 

Hi Will,
My advice is that for all RF/Microwave design use always capacitors ATC series 600. They have L, S and F families that should be chosen according tho the frequency range and power level. These capacitors are full characterized and their models can be included in simulation files to increase the chances the design will work, out of the first round. Another good quality RF-Microwave capacitors vendors are DLI and Johanson.

I hope this can help you,

Nando Pinheiro

 

Thank you for the reply. I will look into the manufacturers you mentioned.

For the prototyping stage I can surely stick to a ceramic NPO capacitor for the value mentioned?

 

Thank you for the reply. I will look into the manufacturers you mentioned.

For the prototyping stage I can surely stick to a ceramic NPO capacitor for the value mentioned?

NPO has higher loss