A 100W 49:1 UnUn in the palm of your hand.
This looks too small to handle 100W – even to me. It is only 64mm long excluding connectors, and 33mm in diameter.
Yet I’ve pushed 100W SSB into this for an hour QSO and without ill effects.
The reason is that it is a high efficiency UnUn. We used a nanoVNA and did S21 through loss test using a resistive terminator. It shows a loss of 0.1db from 3.5mHz to 14mHz. This means it easily handles 100W of SSB in such a small package.
Not only that, it is small, low cost and robust. It will slot into your go-bag rather nicely. It is easy to use and “not ugly” – you’ll be proud to use it.
A small note – this UnUn and all the ones we make work down to 80m – 3.5mHz because of the winding we use. It is optimized for the lower end of HF. On 10m for example it has 0.3db of loss which is not ‘fantastic’ but still low at 1/18th the loss of an ‘S’ point.
Keen observers will see a black banana post for connecting radials. These are optional with this design – or you can allow it to just use the coax as its radial.
In our experience, using short radials reduces common mode current and we suspect they help with efficiency and pattern.
edit : I shouldn’t show favorites but this classic UnUn is getting close to being a favorite. I put one in my pocket last week and now, the day before Christmas it’s still there.
update. An even smaller OZ-Pipe UnUn is in final testing – 27mm in diameter, 50mm long – and great for 50W SSB – but no banana post for radials.
What About a 1:1 Then?
The dirty secret of classic EFHW UnUn’s is that you quite often need a 1:1 balun to tame the common mode current. These are also called a common mode choke or a line isolator.
Here is the OZ-Pipe 1:1 Balun with SO239 connectors you can install in-line in your coax. You can get it in BNC also. Just ask.
So What About a Hybrid Unun?
On showing a friend the classic 49:1, he loved the size and shape of the OZ-Pipe UnUn. He loved it! I could see his eyes glazing over probably wondering if it could find its way into his pocket – then he asked if it has a 1:1 inside. Then he was disappointed when it didn’t. So he asked for that.
A day later the OZ-Pipe Hybrid UnUn was born. It’s 30mm longer for a total of 94mm excluding connectors, to fit the extra magnetics inside.
So here it is, the OZ-Pipe Hybrid UnUn. It handles 100W SSB with ease and should not need a line isolator. It is 94mm long by 33mm diameter. While being longer than the classic UnUn it is still ‘pocket friendly’ and does pack down well.
Remember, you must use radials with this product.
On Air Tests
Pretty much the least conclusive test is actually putting 100W SSB into a product then seeing how it handles the power.
After an extended QSO, pulling the device apart and checking core heating gives an idea of power handling.
The answer is…. well…. no big deal. Core heating was negligable. It works just like all the other UnUn’s and hybrid UnUns tried at the same time. This was precisely as expected. By ear it is impossible to tell the difference between the range of UnUn’s.
In another post I’ll tabulate the common mode current measurements I took with all products.