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Monday, 14 September 2015

Baluns - Yet Again!


Part of the Windom I made last time here was a 4:1 balun. Now I tested one of those way back in time here. Back then I didn't much like what I saw as the frequency increased - it looked like the balun was only good to about 4MHz.

I came home with one of these the other day:

I bought in from LAM Communications in Barnsley.

Now, I repeated the tests I did way back when on this new balun and got more or less exactly what I expected. Here I am inputting a signal at 2MHz into the balun and looking at the two signals out. My expectation is that these two signals should be 180 degrees out of phase, as they are here:

The yellow and blue are the two outputs and the purple the difference between the two.

Now, as I increased frequency the last time I tested a balun this picture got very much "out of bonk" (a technical phrase meaning broken) with the phase difference between the signals moving significantly. On this balun all seems well at 25MHz and higher:

So - this balun seems to have good performance over the advertised range of frequencies - much better than the last one I tested!

As a consequence this is the balun installed on the new Windom.

Local conditions.

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