Lego helps to hold the cable...

My son is a heavy LEGO-fanatic. He has two characters he does not like to play with. I decided to recycle them in the perfect way. Now they are slaves and holding my usb cables on the side of a shelf. 

Pictures tell everything, nothing more to say:)

One more antenna tuner

Recently I made an antenna tuner (can be found below) for HF QRP portable operation. I am pretty satisfied with it. It is solid like a rock, not too big and does the job it needs to do. Good as it was I felt I need to build a new one with some more features. 
I built a switchable 1 to 4 and 1 to 9 broadband transformer to the end of the "L" network. It is a MUST! After testing several tuners with high impedance random antennas I decided to use transformers after the tuning circuit. Sometimes you can double or triple your signal. In QRP field operation the it means you can just jump above the noise floor. 
In dark environment the led was so easy to use. Making difference between transformed and straight mode signal with the led is complicated. I simply could not remember exact light strength after tuning, while needle tells the truth so accurately. Hence I built in a small led and a lithium battery. The switch of the meter gives power to the led in one position. 
Experiences are so nice with the new monster. Yes a monster, because it does not look good, but it really does it's job as I expected. 

I had a sick idea and tuned my 1.5m long telescopic whip indoor on 80m band. SWR was 1:1. I touched the whip when testing with 0.25W. I felt the RF burning my skin. It was impressive. Of course I don't plan to use my short whip on 80, but it was clearly visible the power entered the tuner was not lost finally.

After the first tuner I received mails saying "please send a schematic".
Well, here it is. Sorry for the ugly sketch, I don't have any sort of cad software to draw fancy schematics, paint is so "paintful" for me:)

Important! There is a 5 pF capacitor between the antenna and the tuning aid circuit (diodes) I was tired when sketching. 

Coils are mainly on toroid cores, except the fist three ones. DPDT switches are used, so coils are isolated when not used. The transformer is a standard 1:4 and 1:9 broadband one. I used a ferrite toroid core I tested before. It shows no significant loss from 3.5 to 30MHz. Variable cap is an old plastic one. I used the the two caps serial to reduce the stray capacitance. The meter is also from an old CB radio, while germanium diodes are ABT 60 yrs. old Hungarian "Tungstram" models. 

Few words about the meter light... There is a bright led fed by a lithium battery. It will be enough for the next decade I think. To have a really nice dimmed light around the meter all you need is some sand paper to polish the surface of the led a bit. It will become matte white with no such a magnifying glass effect at the tip of it. I use to change old meter lights in CB radios exactly the same way with very nice result. 

Some pics from inside:

You can see the old plastic capacitor in the middle. The RF choke on the left was there just for test reasons. You can see the small coils on the left and the high inductance on the right.

Finally here is the front end.

Not too nice, but works amazingly good. I am not going to stick labels to the switches. Everything is so easy and straight-forward. The line of switches on the top is the inductance. Switches on the middle belongs to the capacitor. The right side is the output. The first switch on the right column is to select between straight output and the transformer. The next is 1-4 or 1-9. It is a three position DPDT switch, so the output is not connected to the transformer when it is in mid. position. Below that  the meter switch and the big knob on it's left is the variable cap. The one on the left below the 36uH switch has no function. The knob on the left is the pot of the meter sense.

The UHF connectors at the two ends makes the tuner able to be used even mounted to a PL magmount with whip inserted right to the top of it using the output connector. Also it can be connected directly to the radio with a 90 deg. coupler and used with the whip. The banana plug on the right is the gnd. It is ideal for connecting counterpoises. (recommended)

The circuit is not a new thing, it is more like "inventing hot water". One can find several ideas like this. It does not have source, it is so so evident, even I wasn't born with this idea in my head...