Tuesday 19 November 2013

New ATV 5 Watt Class-A amplifier

Last week Erwin, PE2ER, informed me that he had an assembly kit of a 23 cm amplifier. Since I am involved with some ATV activities these days, he asked me if I could use this kit. I struggled with some PA designs last weeks ( with power modules or CLY15) and therefore I was very glad with this offer. 
Last sunday I assembled the 1.2 GHz amplifier which is a design of PA0VRE from 2002.
It contains two SHF transistors: A BFQ68 and a BFQ136. The amplifier is able to generate 5 Watts RF power at 1.2 GHz with 200 mW input.
Assembling the kit was a delicate job. Some very small SMDs (2p2) had to find their way to the pcb and the whole circuit is mounted on a heatsink. 
All details are here: http://www.van-rees.nl/23pa/versieNL.PDF

Anyway, after building the first test on the bench were promising.


                                             The 23 cm amplifier finished

This morning I connected the amplifier to the ATV baseband circuit, connected the biquad antenna to the amp and pointed the antenna to the local ATV repeater and switched the power on.
A nice steady ATV signal at 10 GHz from PI6ZTM came back for me:

                  
    My 1255 MHz ATV signal (LH upper corner) arrived at the PI6ZTM repeater


 LNB for 10 GHz reception and dual quad antenna for 23 cm transmissions. With this    antenna setup a distance of 4.2 km between my QTH (JO22gb) and the repeater on "De Blankaard" (JO22fb) is bridged.



Steady ATV FM signal

I am curious what is possible with the 1.2 GHz Watts available now. Maybe, now it is also time to give my ATV antenna a permanent place on the roof.
Thanks Erwin !



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