Possibility of using cfl ferrite toroid cores as low pass filter for hf band

[Dom13c]

I am trying to put together the Michigan mighty mite transmitter for doing some Qrp with it.  I've gathered everything but the ferrite cores needed to construct the low pass filter. I was wondering if I could use green ferrite cores from old cfls. Buying them online from suppliers like Amidon is quite expensive for me. If possible mention the upper and lower limit of the working frequency of those toroids salvaged from the cfls.

[T3sl4co1l]

What LPF?
http://www.qsl.net/wb5ude/kc6wdk/transmitter.html

I don't know offhand what those green cores are, if ferrite or powdered iron.  Good bet they're a low frequency material, whatever it is, unsuitable for RF (unless what you were looking for is a resistor).

If you mean an LPF before an antenna, that needs to be low loss, stable value inductors, which ferrite toroids are unsuitable for.  Powdered iron types are good, the ones intended for RF (the ones intended for power switching are terrible).  Otherwise, there's always air core coils.

Tim

[HB9EVI]

Unknown toroids are a plain source of trouble. Without knowing the properties, you cannot match the needed usage for it.
spare you the time, working on that and directly get the right toroids, as lpf you would choose powered iron toroids from Micrometals, material -2 for up to 10MHz and material -6 for above

[Dom13c]

Sorry.😝😝 I forgot to mention that they are for LPF before antenna as you've mentioned. Ain't it even possible to utilize those cores as RFC?

[Dom13c]

What you've said is absolutely true. Can you mention a place in India where I can get those T13-9 or T20 type toroids for a better and cheaper price than many other online suppliers.( don't mention mouser , in our country they've sort of taken pledge to rip our pockets off. They take near about 1$ each for every single rf toroid , being a hobbyist it do is pretty much expensive to me)

[xaxaxa]

What you've said is absolutely true. Can you mention a place in India where I can get those T13-9 or T20 type toroids for a better and cheaper price than many other online suppliers.( don't mention mouser , in our country they've sort of taken pledge to rip our pockets off. They take near about 1$ each for every single rf toroid , being a hobbyist it do is pretty much expensive to me)

Aliexpress

[HB9EVI]

I ordered already some powered iron toroids on aliexpress; the majority was fine, but I've got some T50-6 which absolutley don't reach the Q they should have according to the specs. It pretty much seems that even with toroids you have to watch out what you get.

btw. what is material -9? I don't find in the micrometals list.

don't go too small with the toroids. Not only it's a pain winding them, also the achieveable Q is lower than with the bigger ones; personally I don't go smaller than T37-xx

[Dom13c]

I ordered already some powered iron toroids on aliexpress; the majority was fine, but I've got some T50-6 which absolutley don't reach the Q they should have according to the specs. It pretty much seems that even with toroids you have to watch out what you get.

btw. what is material -9? I don't find in the micrometals list.

don't go too small with the toroids. Not only it's a pain winding them, also the achieveable Q is lower than with the bigger ones; personally I don't go smaller than T37-xx

[vk4ffab]

The michigan mighty mite is only going to be putting out 1/2 a watt at most, just use molded inductors of a similar inductance if they gave you numbers, if not just design a low pass filter around fixed value inductors you have in your parts box.

I notice in your other post you have difficulty finding toriods, you can get them from Mini Kits in Aus, you will want iron cores in type 2 and 6 and ferrite cores in type 43 for your amp transformers.

https://www.minikits.com.au/