[hpsdr] Broken Pennywhistle any ideas ?

[Graham / KE9H]

Steve:

Are you running the Pennywhistle off 12 Volts?  For rated power output, 
it should
be running off the 13.8 Volts supply, not the 12 Volt regulated supply, 
and it should not
draw anything through the LPU.

As long as you have some kind of load on the output, 100 percent drive 
from Penelope
should not hurt PennyWhistle.

With the pots fully counter-clockwise, Pennywhistle should not be 
drawing any
significant current.  With the pots fully counter-clockwise, what DC 
voltage do
you have on the gates? Measure at the bypassed end of the 56 Ohm resistors.
Should be about 2 Volts.  A good FET should not start conducting until more
than 2.5 Volts on the Gate, and should be drawing the desired 450 mA 
quiescent
current with about 4.7 to 5.1 Volts on the gate.

--- Graham / KE9H

==

Steven Doyle wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
>   
>
> ------------------------------------------------------------------------
>
> Hi,
>  
> I accidently blew up pennywhistle Sad smile emoticon. I'm afraid I 
> drove it with 100% drive and gain I also took out the LPU Sad smile 
> emoticon
>  
> Anyway, I have replaced the mosfets, the 6 V regulator and Q3 and 
> tested the electrolytic capacitors, but no joy.
>  
> When I short the bias and ground in order to set the DC bais 
> currents(pots set fully counter clockwise), I see a voltage drop on 
> the supply, it drops to around 2V. I can't think what might be causing 
> this (duff capacitor ?)
>  
> Just wondering if anyone has any ideas or other tests I can do.
>  
> 73s
>  
> Steve
> G1YLB
>  
>  
> ------------------------------------------------------------------------
>
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