ARCHIVE: Australian Ham Radio Discussion Forum ( AHRDF )

Hi To All,

I am about to go down the Non-Resonate End Fed path as it better suits my current location.
In the Philippines where I am currently, we are able to use full legal limit as far as power is concerned.

With that in mind, the UNUN will need to be able to handle such power when or if ever needed.

To handle the power I am looking at using 3 x Toroids but I am unsure what mix to go for.
I have a 2 x F240-43 Unun but expect it will get warm so I am looking for the correct mix to use.

I have heard that the 52 mix is to be using in high power environments, but others say 31, thus the confusion.

The antenna is around 145' long and up 25' parallel to the ground. The unun will be at the same height.

So, what do you think??


Pete VK4CCV/DU7
Camotes Islands, Cebu.

For 9:1 unun I prefer lower mu ferrite toroid such as 61 or 52 with 8-12 turns by experiment. The 52 ferrite has a higher curie point thus maybe better for high power (watch out your plastic case).
Also a 9:1 with random EF-wire seldom provide an ideal 50-ohm load, so not recommend for QRO (unless use an ATU).