Power curve flattening in the driver and pre-driver stage

Glenn VK3PE is attempting to flatten the power curve from the µBITx by playing with the driver and pre-driver stages. 

He has completed his mockup of the PA driver stages and

  • used MPSH10’s in all stages.
  • Used FT37-43 toroids all wound with 10 turns 0.25mm wire either tri- or bi-filar according to original Sch.
  • Bypassed all emitter resistors with a 220pF cap.
  • swept from C80 input to T10 secondary (as wound)

The result is a very flat response: better than 1db from 3Mhz to 54MHz.

Glenn plans to mock up the finals now to see what the net impact is on the power response curve.  If it is nice and flat he will replace the parts in the µBITx and we will have a solution that everybody who wants to flatten the power curve can use.

Reference

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