[ARC5] Input impedance - BC-453-B - un-un

[Kenneth G. Gordon]

On 4 Feb 2015 at 20:57, Dennis Monticelli wrote:

> 
> Guys,
> 
> Maybe we're over-thinking this input matching "problem."

Well, I haven't viewed it as a "problem": I am simply very curious whether 
matching the input impedance could make any difference, either good or 
bad.
  
> If the input parallel tuned tank's parallel resistance at resonance is in the
> neighborhood of 50K ohm (as Ian reports), then let's ask ourselves what a 50 ohm
> antenna looks like after passing through the series 8.5pF input coupling cap. 
> The series circuit of 50 ohms and 8.5pF need only be transformed into its
> parallel equivalent circuit to answer that question.  Doing the mathematical
> conversion at 400KHz results in 44K ohm in parallel with 8.5pF.  The
> capacitance will get absorbed by the antenna trimmer leaving 44K of antenna
> source resistance.   
> 
> I just don't see a need to be fiddling with input matching networks.  And let's
> give the ARC-5 designers the credit they deserve.  

Well, as I have repeatedly stated here, as far as I am concerned, the ARC 
engineers were pure geniuses. They appear to have thought of everything.

Ken W7EKB