DIGITAL 1 Watt ATV FM TRANSMITTER FOR 10GHz
The 10GHz Transmitter is tunable over the whole of the ATV 10GHz band in 500KHz steps and also this design 4MHz steps. The heart of the Frequency Generation was taken out of a Farnell Stealth 2.4GHz FM TV Sender TX and gives out at least 10m/W and can if required give a little more at the expense of matching isolation. The surface mount chip PIC16F84 is removed and is not an easy task just look at Picture (1). I removed the side plate to get at it. Then I reprogram it to go up to 2.57875GHz and drive the Display and the four up/down Frequency Buttons. This is then fed into the WDG times four multiplier so that we get about 60m/W out on 10.315GHz see picture (2) and (4). I actually only need 17m/W to drive the DL2AM German 1.2 WATT P.A. a very good design and well worth the money and it has a monitor output circuit so that you can see if things are working fine or not........
For safety reasons I would run the PA at about 1 Watt then you are not causing overdrive conditions and distortion. The only problem I had was that when you go more than say 20/30 MHz the times four multiplier drops off its output power not due to the Synth Driver but to the cavity. However the unit was originally designed I suspect for narrow band stuff....But lets face it we tend to all stick around common frequencies so I don't see a problem...One could reduce the Q of the filter if you have time to play......Due to the unlinear way multipliers work I found that at 10GHz the sound to carried level had changed by more than 10db unless its my Analyzer but I just simply reduced the injection at 6 MHz to effect a cure. to give about -20dbc....again I used the same displays as in the other articles and stored the last frequency in the PIC EEFLASH....The replaced software multiplied the Display reading by four ........G3RFL