Transmission Line Transformers

[kandrey89]

Hi,

I'm itching to build some, but I have some questions:

1. The term broadband when used in relation to TLTs seems to refer to 1-50MHz max, not exactly the 30-800MHz I'm looking for. While I realize that they are mostly for high power 1-50MHz amateur transmission impedance matching, is there any core material that is useful at 30-500+MHz?

2. Is there a guide or a reference sheet somewhere that lists various core materials and their use cases, parameters and qualities?

3. What is it about permeability? How is higher/lower permeability related to frequency cutoff? How is it related to power both in receive only mode, low transmit and 50W+ transmit?

I'm slowly going through Amidon's TLT Ref Handbook, and I also got Sevick's book but haven't had the chance to start it.

Thanks

 

[prcguy]

Is this for something like a 4:1 transformer/balun? Type 43 material can be used for HF through about 400MHz and maybe higher for small transformers made on binocular cores that will handle 100w or so. If this is just for receive then you can use smaller ferrite cores or beads and push the frequency range up to 800MHz or more but you will loose some of the lower end on HF.
prcguy

Hi,

I'm itching to build some, but I have some questions:

1. The term broadband when used in relation to TLTs seems to refer to 1-50MHz max, not exactly the 30-800MHz I'm looking for. While I realize that they are mostly for high power 1-50MHz amateur transmission impedance matching, is there any core material that is useful at 30-500+MHz?

2. Is there a guide or a reference sheet somewhere that lists various core materials and their use cases, parameters and qualities?

3. What is it about permeability? How is higher/lower permeability related to frequency cutoff? How is it related to power both in receive only mode, low transmit and 50W+ transmit?

I'm slowly going through Amidon's TLT Ref Handbook, and I also got Sevick's book but haven't had the chance to start it.

Thanks

 

[kandrey89]

Doesn't seem promising above 40MHz...
http://www.amidoncorp.com/product_images/specifications/2-48.pdf

 

[majoco]

What about those "binocular" cores that were used in TV antennas, supposed to cover 50MHz to 600MHz.

 

[kandrey89]

Don't you just want one of these to make all your questions disappear?
https://www.youtube.com/watch?v=NT3sGk6bGkU

You can buy most of Amidon's toroids in various sizes and materials to perform hundreds of characterizations for only $90 plus $20-40-60 for enamel wire of different gauge.

 

[majoco]

Magic. I would like to say that I need one, but I don't. I have a Tektronics time domain reflectometer plug-in that works well.

This probably went right over the OP's head.

Most of the fun with transformers is - suck it and see.