It is now Christmas time 2020, and I decided to build a tuner for my HF Amplifier. The reason is simple. I have a mono band inverted V antenna for 20m, which is tuned to about 14.100 MHz. SWR is about 1 : 1.2. But going to the borders of the band, the SWR in increasing to about 1 : 1.3 which is by the way not bad at  all. But for all other bands the antenna is not that good. I also have a dipole in the garden. For 80m The borders of the band are going to 1 : 3. For 60 it is even worse. 40m is not that bad but at 7.200 it is also going to the 1 :3. 30m is bad. Everything above 20m is terrible. The reason I can be QRV out on these bands is that I have bought a MFJ-929 tuner for max 200W.

It works OK, but I burned it now twice, using only 100W. The diodes in the bridge were only OK for 100V. I changed them to bigger diodes handling up to 200V. Now I don't burn the diodes anymore, but still it is not good enough for my Amplifier, which is giving over 500W.

So I decided to dig into the world of HF high power (QRO) tuners. And I see an enormous challenge ! Come along , and ride with me,...

Loek Veeger, PE0MJX

 

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