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DIY kits 70W SSB linear HF Power Amplifier For YAESU FT-817 KX3

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It's time for a new project.   eBay link to the seller                   

OM's in need of a doc. copy please send me a mail , i'm happy to help.  E-mail adress at QRZ.com
It seems that the seller often forgets to add the doc. ....
My first impression : High quality PCB , all parts in the kit including 2 power FET's type IRF530N.
However i had doubts about the claimed 70 Watts output at 13.8V  for these fets are normally fed with 24 - 36V to get a good modulation. 

The first test was in the original configuration at 13.8V and 5Watt input from my FT-817. Max. power 80 Watt but the input swr on tx was 1:2.2 much to high. At  4 Watt input the swr drops to 1:1.5
Output was about 65W at 20m.but the modulation was as expected distorded at  2.7V bias voltage.
At 3.7V bias the modulation is verry acceptable.
5 Watt transceivers need a 1 dB attenuator to work with this Amplifier.






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