[hpsdr] penny/pennywhistle

[Graham / KE9H]

Geoff:

After thinking about it, I have devised a test for T2.

Remove it from the board.

Then try to operate the power amplifier.

If T2 was the problem, then the amplifier will operate
at about 60 percent of rated power, which is a lot better than
the "almost nothing" you are getting out right now.
The DC power to the drains will still be supplied through
the primary of the T3.

Then, when you put T2 (rewired) back into the circuit ...

If it is wired correctly, the output power will go up.
If wired incorrectly, the output power will go down.

But the amplifier will partially/mostly work without T2
present.  If you want full power and linearity, then it needs
to be there.

--- Graham / KE9H

==

On 11/6/2011 8:33 AM, Graham / KE9H wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Geoff:
>
> The exact wire size is not critical.  The bigger the better, as long 
> as two
> pieces twisted together will still fit through the hole in the ferrite.
>
> --- Graham
>
> ==
>
> On 11/6/2011 2:53 AM, Geoff wrote:
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>>
>> Hi Graham et al,
>>     I checked out Penny carefully, set it up properly (thanks Phil) 
>> and it's
>> good. With reasonable power now available I checked the input SWR of
>> Pennywhistle as per the manual. T1 on Pennywhistle passed that test. 
>> It thus
>> appears that I somehow screwed up the wiring/winding of T2. Given 
>> that it's
>> Sunday evening, I'm getting hungry and I don't have any #22 wire 
>> repairs will
>> have to wait. Can anyone recommend a suitable metric equivalent to #22?
>>     Thanks for the help I've received thus far :-).
>>
>> 73 de Geoff vk2tfg.
>>
>>
>> On Sun, 6 Nov 2011 12:38:34 am Graham / KE9H wrote:
>>> Geoff:
>>>
>>> It sound like the RF amplifier transistors in PennyWhistle are
>>> biasing up fine.  Recheck the wiring of, and in particular the
>>> directions of the windings in T1 and T2.
>>>
>>> --- Graham
>>>
>>> On 11/5/2011 2:14 AM, Geoff wrote:
>>>> ***** High Performance Software Defined Radio Discussion List *****
>>>>
>>>> Hi guys,
>>>>
>>>>     I am presently trying to get my completed Rx/Tx setup going. On 
>>>> Tx I
>>>> have a problem (or 2, dunno). My unmodified TAPR Penny is putting 
>>>> out the
>>>> expected power level. Pennywhistle has been setup as per the 
>>>> manual. I am
>>>> getting much lower power levels than i should. Most bands give me 
>>>> between
>>>> 400 and 600 mW, 10m gives me 1.5W. 6m gives less. Penny whistle 
>>>> draws a
>>>> maximum of about 2A on 10M. My aimless fiddling with gain and drive
>>>> levels in powersdr gave some small improvements but nothing 
>>>> significant.
>>>> Any attempt to run the PA calibration routines results in powersdr
>>>> throwing a wobbly over invalid calculated gain. I am transmitting via
>>>> Alex into a Bird 82C dummy load (overkill I know)
>>>>     Any ideas you can give me to get my HPSDR system up and running 
>>>> properly
>>>> on Tx would be much appreciated by this frustrated numpty :-).
>>>>
>>>> 73 de Geoff vk2tfg.
>>>> _______________________________________________
>>>>
>
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