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Sotabeams Pico EFHW tuner [solved]


Hi everyone.
I recently bought a couple of Pico Tuner kits from sotabeams https://www.sotabeams.co.uk/pico-tuner-end-fed-half-wave-tuner-kit/
I decided to set up one for 17m and the other for 30m band.
I carefully followed very clear step by step instructions. I’m able to make the primary winding around the toroid and find a resonance point very close to the desired frequency

Then I install the 4.7K and the resonance is still there even if less sharp:

Then I wind the secondary winding with only 2 turns around the core (as suggested by the instructions). I solder 5m of RG174 cable and I connect it to the antenna analyser. This is the result:

Resonance completely disappears across 10Mhz… I must be doing something wrong but I can’t understand what.
I also “rolled back” step by step the circuit and I was able to find the resonance when only the primary winding is on the toroid.

Any ideas on what I could be doing wrong?



Did you think to email the supplier for help?


Of course I did Richard.
Then I thought how much I value the ham community and that maybe other people might have experienced the same issue or might experience that in the future and they would be happy to find a solution on a public forum just using google rather than writing an email.
If you prefer to keep it private I’m happy to contact you via email.



We provide customer support by email. If the problem is one that we think is likely to trouble other people we modify the instructions because we don’t believe that customers should have to search on Google for help with our products.

I await your email and I will be very happy to assist.


Will we ever hear the results of this problem?


Last I heard he had found his mistake. Nothing else heard…


(post withdrawn by author, will be automatically deleted in 24 hours unless flagged)


Hi everyone.
As Richard posted above, the issue was caused by a (stupid) mistake I had made. I soldered the inner of the coaxial cable to the counter poise hole on the PCB.
Richard kindly spotted the mistake and I was able to complete the antenna and test it on air with good results over the weekend.

So nothing to update in the assembly instructions which are indeed very clear. Just a reminder for me: avoid building anything late at night after a tough day at work and another couple of hours playing with my toddler kid.

73s Gab


Hi Gab,

full marks to you for acknowledging the mistake, which is a simple one, as they always are. It helps to know that with checking, such mistakes can be identified. Thanks for publishing the details.

The behaviour of the circuit was consistent with the transformer being short circuited.

73 Andrew VK1DA/VK2UH