100 uH coil

[walid1]

how can i wound 100 uH coil

 

[audioguru2]

I use this on in my FM transmitter:

View attachment 37580

 

[Staigen1]

I use this on in my FM transmitter:

Eh, 100 uH?

//Staigen

 

[audioguru2]

Hi Staigen,
Didn't you see my FM transmitter? I found some tiny variable caps to tune it, it has a low-distortion preamp with proper selectable pre-emphasis, the preamp and oscillator have a low-dropout regulator, it has an RF amplifier/buffer so that it doesn't change its tuning if something gets near the antenna and its range is more than about 2km. My FM band is full, so to test it I had to use the same frequency as a foreign-language low-power station on the other side of my city. ;D 

 

[Alun]

That looks more like 100nH than 100uH to me. ;D

 

[Staigen1]

To Audioguru
Yes, i have seen it before, here on the board, a nice little thing, built on a wero and all! Nice! ;D ;D
BTW, have you notice my message(question)?

To Alun
I agree with you, suddenly not 100uH!

//Staigen

 

[audioguru2]

Hi Staigen,
You are absolutely correct! My coils are only 100nH. I think Walid recently posted an FM transmitter circuit using 100uH by mistake and I didn't notice its error. :-[

 

[Staigen1]

Hey Audioguru, did you get my message?

//Staigen

 

[audioguru2]

Yes I did and I replied with a link to millions of these thingys:

View attachment 37582

View attachment 37583

 

[walid1]

OK OK guys it is 100uH coil and i can't purchase it, can i use a piece of ferrite rod and wound some turns on it? IF this OK what values (rod length and diameter, n turns etc)

 

[audioguru2]

Our 3W FM transmitter project uses a few RF chokes and tells how to make them:
http://www.electronics-lab.com/projects/rf/016/index.html

One of our 4W FM transmitter projects also uses RF chokes but its translation is difficult to understand.

 

[walid1]

I go to the 3W FM transmitter project which uses five RF chokes==>

L2,L3,L5,L7,L9  5  6-hole Ferroxcube Wide band HF Choke (5 WDG)

but i can't understand anything from this "6-hole Ferroxcube Wide band HF Choke (5 WDG)"
can you explain?
thanks

 

[audioguru2]

I guess the ferrite core is a Philips one with 6 holes for the wire to loop through and has 5 turns of wire in it.
Entering Ferroxcube in Google linked to a site by Ferroxcube. They have a few of these cores and the ones with the highest inductance resonate below 100MHz. Here is a good one:

View attachment 37594

 

[walid1]

Thats what I expect from you Audioguru. it is a good answer
thank you very much