Test of a cheap PCB based end fed half wave antenna

There is a nifty little PCB based end fed antenna Unun and winder being sold in the Chinese stores online. It does look a lot like the ones sold by QRPGuys. The kit comes with the BNC socket, a capacitor, a toroid, some cable ties, the butterfly nut and bold, and a length of enamelled copper wire. It doesn't come with the antenna wire. 

I cut the wire for a 20m band antenna. The flatness of the SWR curve suggests rather high losses in the toroid.

For a 20m band antenna there is enough space to wind the wire around it but I think it wouldn't be enough for lower bands.

Strung up near the house it certainly brings in CW and FT8 signals well on 20m. 

The capacitor doesn't look like a high voltage type and I wouldn't want to transmit more than a very few watts into this. I could substitute the capacitor and toroid. It's very compact and something to throw in the travel bag but I wouldn't trust this for extended digital transmission.