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Re: LF: TXing 2200m WSPR

To: [email protected]
Subject: Re: LF: TXing 2200m WSPR
From: Andy Talbot <[email protected]>
Date: Sun, 24 Dec 2017 23:16:40 +0000
Cc: [email protected]
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Yes

Try anything and try to work out what is happening.  But first of all, he needs to know what power being deliverfed into a 50 ohmsload is seemingly higher than it 'can' be.    The Vdd^2/2/Rl cannot be violated.
If it appears to be so, then Rl or Vdd or the measurement  has to be wrong.

I once had to go though a similar try-everything-and-believe-nothing-until-tested process to work out why my 700Watt 137kHz Tx appeared to be more than 100% efficient!
It turned out my Bird 30dB 1kW attenuator only had 29.4dB attenuation at DC.  And for a 1GHz jobbie, 137kHz is DC.

On 24 December 2017 at 23:03, Chris Wilson <[email protected]> wrote:


Hello Andy,

Is  there  any point in Paul putting his dummy load on the end of his
75  odd meters of feeder co-ax outside? And then on the secondary of
his  matching  transformer when tapped one to one? In case the co-ax is
iffy or the impedance matching transfomer's doing something odd?


Sunday, December 24, 2017, 10:42:16 PM, you wrote:

> Well ...    Using exactly the values in the filter circuit diagram,
> 50R transforms through the filter to 48.5 - j2.86 (Ret Loss = 30dB, 
> VSWR = 1.07)   [Using GM3SEK's original Netcalc prog.]


> So that's pretty conclusive the ideal filter values will not be
> upsetting things at the fundamental frequency.    
> According to Google, the  T106-2 has a stated Al value of  13.5nH
> /turn^2  so 72 turns does indeed give 70uH.   So IF your core is correct, the filter should be OK.


> It's a bit difficult from now on, at a distance, to try to work out what is happening.
> Anyone else, any suggestions ?


> BTW ...


> Peak to peak of a { symetrical }square wave needs to be multiplied
> by 4/pi to get the peak-to-peak of the fundamental component.   So
> the amploitude you see will be lower by about 1.3 times for teh same fundamental power component. 


> Andy  G4JNT





--
Best regards,
 Chris                            mailto:[email protected]



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