[hpsdr] Penelope Output power problem (HELP PLEASE)

[Graham / KE9H]

Steve:

The DAC is currently set to put out a current of about 20 mA, which into 
a 200 Ohm transformer
would produce about 4.4 Volts peak to peak, EXCEPT that the output stage 
of the DAC
hard clips at +/- 1.1 Volts.  The power control loop in the FPGA further 
limits the level
to keep the output out of clip.  T3 is a 2:1 voltage (4:1 impedance) 
step down transformer, so results
in 600 to 700 mV peak to peak at JP3, with the power/control loop at 
maximum.

(I was in error the other day when I said 1.2 Volt, I was thinking of 
the voltage at the input to
the transformer.)

Look for DC voltage on the two DAC output lines.  They should both be 
held at 0 Volts
by the transformer.  If there is any DC voltage, there is a problem with 
T3, or solder joints.

--- Graham / KE9H

Steven Doyle wrote:
> Hi Graham, Gerd
>
> With the board powered off I can confirm that I have continuity 
> between JP2 pin 1 and JP3 pin 1. When powered the voltage at JP3 is 
> 234mVpp so it looks like the problem is with T3 or the DAC.
>
> As I understand it(probably incorrectly) the DAC has a full scale 
> output current of 20mA so with the 220 R7 this should give arround 
> 4.4Vpp at the primaary of T3(4:1) giving arround 1Vpp at the secondary.
>
> Measuring the voltage pp at R7 gives the same 234mv implying that DAC 
> is not at full scale and also that T3 does not seem to be 
> working(assuming my understanding of the transformer coupling is correct)
>
> So what next ?
>
> 73s
>
> Steve
> G1YLB
>
> ----- Original Message ----- From: "Graham / KE9H" <KE9H at austin.rr.com>
> To: "Steven Doyle" <steve_doyle at o2.co.uk>
> Cc: "Gerd Loch" <g.loch at nt-electronics.de>; "hpsdr" 
> <hpsdr at lists.hpsdr.org>
> Sent: Thursday, April 23, 2009 12:41 AM
> Subject: Re: [hpsdr] Penelope Output power problem (HELP PLEASE)
>
>
>> Steven:
>>
>> The gain of the OpAmp output stage is about 23 dB.
>>
>> So for 1/2 Watt out, you need +27 dBm - 23 db or +4 dBm
>> into T1 for full output.
>>
>> Check for about 1 Volt peak to peak at JP2 pin 1 or 2.
>> Look for about 1.2 Volt peak to peak at JP3 pin 1 or 2.
>>
>> If not getting that, then look for problem between there and
>> the DAC.
>>
>> --- Graham / KE9H
>>
>> ==
>>
>>
>> Steven Doyle wrote:
>>> Hi,
>>>
>>> I have done some testing and checked the following.
>>>
>>> Gert Build Penelope so T2 installed correctly
>>> Tune Power set to 100
>>> Drive set to 100
>>> PA Settings set to 38.8
>>>
>>> The output of T1 is 236mV(Peak to Peak) and the output of the 
>>> operation amplifier circuit is 2.4V(Peak to Peak)  which looks 
>>> correct to me as I believe the gain is set to 10. Maybe the input 
>>> (236mV) is low I don't know.
>>>
>>> Any further ideas or what these voltages should typically be  ?
>>>
>>> thx
>>>
>>> Steve
>>> G1YLB
>>>
>>> ----- Original Message ----- From: "Graham / KE9H" <KE9H at austin.rr.com>
>>> To: "Gerd Loch" <g.loch at nt-electronics.de>
>>> Cc: "'Steve Niles'" <n5en at wt.net>; "'Steven Doyle'" 
>>> <steve_doyle at o2.co.uk>
>>> Sent: Wednesday, April 22, 2009 6:33 PM
>>> Subject: Re: [hpsdr] Penelope Output power problem
>>>
>>>
>>>> All:
>>>>
>>>> On the US built Penelope, and I assume on Gerd's Penelope, the
>>>> power control loop will start to go unstable, (a very low frequency AM
>>>> modulation appears on the signal) if you set the PA settings between
>>>> 38 and 38.6.   This is why I recommended a PA setting of 38.8 or 39
>>>> rather than 38.
>>>>
>>>> --- Graham / KE9H
>>>>
>>>> ==
>>>>
>>>> Gerd Loch wrote:
>>>>> Hi,
>>>>>
>>>>> The transformer is assembled according to the errata.
>>>>> All Penelopes were tested for correct output. On 6m however the 
>>>>> output
>>>>> is down to about 120 mW. This is the case for all Penelopes and is 
>>>>> due
>>>>> to the design.
>>>>>
>>>>> You can compensate differences in output through "PA-Settings" 
>>>>> where you
>>>>> can adjust the gain of the PA. That means a lower value for PA gain
>>>>> result in a higher output from Penelope.
>>>>>
>>>>> If you set all PA-settings to the lowest gain (38) the output is 
>>>>> up to
>>>>> 500mW on 80m and slightly less on the higher bands.
>>>>>
>>>>> 73, Gerd
>>>>>
>>>>>
>>>>> -----Original Message-----
>>>>> From: Graham / KE9H [mailto:KE9H at austin.rr.com] Sent: Wednesday, 
>>>>> April 22, 2009 2:28 AM
>>>>> To: Steve Niles
>>>>> Cc: Steven Doyle; g.loch at nt-electronics.de
>>>>> Subject: Re: [hpsdr] Penelope Output power problem
>>>>>
>>>>>
>>>>> Yes, if it is one of Gerd's Penelope's, then the transformer 
>>>>> should be
>>>>> installed correctly.  I guess I didn't read all the way to the 
>>>>> bottom.
>>>>>
>>>>> --- Graham /KE9H
>>>>>
>>>>> ==
>>>>>
>>>>> Steve Niles wrote:
>>>>>
>>>>>> Surely Gerd installed the transformers per the errata... Right Gerd?
>>>>>>
>>>>>> Steve N5EN
>>>>>>
>>>>>>
>>>>>> Graham / KE9H wrote:
>>>>>>
>>>>>>> ***** High Performance Software Defined Radio Discussion List *****
>>>>>>>
>>>>>>> Steve:
>>>>>>>
>>>>>>> Is the drive level set all the way to 100 for the test?
>>>>>>>
>>>>>>> Also, you need into PowerSDR under
>>>>>>> SetUp,
>>>>>>>   PA Settings,
>>>>>>>        and set all of the PA setting windows to 38.8.
>>>>>>>
>>>>>>> This will usually get you up to about 300 mW.
>>>>>>>
>>>>>>> If you still want the full 500 mW, refer to the Errata
>>>>>>> sheet for Penelope in the Support section.
>>>>>>>
>>>>>>> http://hpsdr.org/support.html
>>>>>>>
>>>>>>> This explains that you must reverse the output transformer to 
>>>>>>> get the
>>>>>>>
>>>>>
>>>>>
>>>>>>> full rated output.
>>>>>>>
>>>>>>> --- Graham / KE9H
>>>>>>>
>>>>>>> ==
>>>>>>>
>>>>>>>
>>>>>>> Steven Doyle wrote:
>>>>>>>
>>>>>>>> ***** High Performance Software Defined Radio Discussion List 
>>>>>>>> *****
>>>>>>>>
>>>>>>>> forgot to add that I am running the following versions
>>>>>>>>
>>>>>>>> PowerSDR 12Apr2009
>>>>>>>>
>>>>>>>> Firmware
>>>>>>>> Ozy FX2:20090201
>>>>>>>> Ozy 12
>>>>>>>> Mercury 26
>>>>>>>> Penelope 11
>>>>>>>>
>>>>>>>> thanks
>>>>>>>>
>>>>>>>> Steve
>>>>>>>> G1YLB
>>>>>>>>
>>>>>>>> ----- Original Message ----- From: "Steven Doyle"
>>>>>>>> <steve_doyle at o2.co.uk>
>>>>>>>> To: "hpsdr" <hpsdr at lists.hpsdr.org>
>>>>>>>> Sent: Tuesday, April 21, 2009 10:37 PM
>>>>>>>> Subject: [hpsdr] Penelope Output power problem
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>> ***** High Performance Software Defined Radio Discussion List 
>>>>>>>>> *****
>>>>>>>>>
>>>>>>>>> Hi All,
>>>>>>>>>
>>>>>>>>> I just received my new Penelope from Gert(thankyou), but I  am
>>>>>>>>> unable to get anything like 0.5W out.
>>>>>>>>>
>>>>>>>>> With the PA gain set to min (38dB) in PowerSDR and the drive 
>>>>>>>>> level
>>>>>>>>> set to 100  I am only getting 49mW out on the display when I 
>>>>>>>>> select
>>>>>>>>>
>>>>>
>
>
>



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