[hpsdr] munin idle currents strange behaviour - solved

[Georg Prinz]

Hello,

I had following situation:

after setting all idle currents according Kjell's recommendation the 
output power was on
80m 50W and on all other more or less 3 W. But, when changing the idle 
current during
operation I got over 100W on all bands. The curious part was, that the 
idle current of each
transistor and band was different - that means asymmetrical.

The reason was that the pushpull amplifier was not driven symmetrically 
with a phase shift
of 180 deg. The culprit was L2 which was wrong done. You can check it 
very easy with an oszillograph
at gate T3 and T4. You need a phase shift of 180 deg.

Now on all bands I get enough power easily. The measurements will follow 
soon.

73, georg, dl2kp







Am 08.09.2012 13:49, schrieb Kjell Karlsen:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi all builders of Munin.
>
> I have forgot to mention the possibility to measure the idling current 
> in the transistors by measuring the voltages on TP1, TP2 and TP3.
>
> If the preamp is in use, 1 Volt on TP1 of course corresponds to 200 mA.
>
> TP2: 400mV corresponds to 1A.
>
> TP3: 400Mv corresponds to 2A.
>
> I included this feature to make it  possible to implement the  
> readings in your own transceiver by sending them to the A/D inputs on 
> Hermes or Penny and make new software for this.
>
> 73, Kjell
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