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Re: 1 watt rf amp

Posted: Thu Feb 27, 2020 7:22 pm
by 1608cc
Try 4427 final stage from this schematic. Can You attach photo of your transistor ? Original Motorola should have gold leads and different marks and logo...

Re: 1 watt rf amp

Posted: Thu Feb 27, 2020 8:37 pm
by output
hello the transistor is now solderd in the board now.. the final stage on your diagram is about the same as the one ive copied i no the soldiering on my board aint great but ive been moveing parts thats why it looks so messsy..ive used a fixed voltage biasing on the emitter and base i will upload the diagram i copied i found it on the internet maybe i will try your diagram out

Re: 1 watt rf amp

Posted: Thu Feb 27, 2020 8:42 pm
by output
Screenshot_20200211-035953_Gallery.jpg

Re: 1 watt rf amp

Posted: Thu Feb 27, 2020 9:05 pm
by XXL
That’s because it essentially is part of your “exciter”. You’ve just joined it with coax. You’ve probably made an oscillator and it’s on some random frequency. You need to put the 1w transistor stage on the end of your driver board to keep the leads from acting as an antenna.

Re: 1 watt rf amp

Posted: Thu Feb 27, 2020 11:33 pm
by output
with out the vfo driver it still oscillating so some where ive gone wrong .some how i need to stop it from oscillating ..so it can then be rf amp.

Re: 1 watt rf amp

Posted: Fri Feb 28, 2020 2:26 am
by output
i think the amp is just out of linear mode this is why it oscillating ive used a voltage divider bias for this so im going to change the biasing to fixed.. im in need of a formula for a fixed bias .can any one help with this formula thanks ..