domenica 9 novembre 2014

Back to tubes after a long time

A long time was spent in my Ham life and after beginning when tubes were the only way to be on the air, slowly I left for solid state equipment, as obviously.

My beginning was using a Geloso G4-102 free running VFO and 6L6 tube as a PA, really QRP (2 W I think), and later adding an 807 PA, really a QRO for me.... hi

In the times I left tubes as when I was young and then an electronic engineer the state of the art was about solid state, as it was (and still  it is so) compact, portable and less dangeorus obviously.

But fashion and feeling that you have looking at the red light inside the tube, and the blue light you see in the PA when key is down is something not equal to anything in tech, and so after 40 years, now that I'm living in a countryside I've a little bit time to spend in doing my tubes equipment once again.

So last afternoon I put together the power supply and the the ONE TUBE TX with an EC82 I had in the junk.

The transformer is from a IK0BDO gift and the components are from and old FL101 I dismounted some time ago as it was out of function.

Then it was the time of the tube itself and so the ECL82 found a place on an old pcb I made for a project by IW0BZD, Pino, in the LF reception.
After a while the circuit wa running and a clean note was on the FT817 I use as a monitor and on the spectrum analyzer screen.

But it was just the oscillator part of the double tube, as ECL82 has a triode and a pentode part. SO the amplifier was done accordin various project I found on the web. The main was from Hans Summesr G0UPL.

So at the end I was able to put together the whole TX: oscillator, and PA and PI-Tank using the old FL101 tank and a couple of capacitor I had .
The result is very rugged and so I have to put in a cosmetic form and to do it better, but anyway the first tube TX after a long time was made I this is what I like. Mybe in the winter I'll be able to be in the QRP MAS contest I like so much. Who know...?


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