[hpsdr] Problems Calibrating Pennylane and with LPU, Could Use Some Help

Tue Nov 29 19:17:21 PST 2011

Kjell,

Thanks. I like that suggestion. It sounds really worthwhile.
I'll do it!

73,
Bob
K4QQK

-----Original Message-----
>From: Kjell Karlsen <la2ni at online.no>
>Sent: Nov 29, 2011 12:42 PM
>To: Bob Mahrenholz <bobm at edge.net>, Phil Harman <phil at pharman.org>
>Cc: hpsdr at lists.openhpsdr.org, n4wxe at yahoo.com
>Subject: Re: [hpsdr] Problems Calibrating Pennylane and with LPU, Could Use Some  Help
>
>Hi.
>
>I want to describe the method I use to set the drive to the PA. Luckily I  
>have a good Spectrum Analyzer so by connecting it to the PA via a Power  
>attenuator I can adjust the output on each band so that the  
>intermodulation products are at least -30 dB down from the Peak Envelope  
>Power. I use the built in 2-tone generator in PowerSDR for this  
>adjustment. The Drive slider must be on 100% as Phil mention.
>
>When using the 2-tone generator for the adjustments the power indicated on  
>a calibrated Power Meter will show half the PEP power. If you do not have  
>a Spectrum Analyzer you can use an Oscilloscope instead. The 2-tone signal  
>is seen as a perfectly double sinus LF signal filled with the RF. As long  
>as there are no or low IM products present there will be no "flat topping"  
>of the signal envelope. If the slightest distortion is seen, the IM3 is  
>around -35-40 dBc so set the output to this point. The distortion is  
>increasing very fast, one to 3 dB increase in drive may give 10-15 dB  
>higher IM3 (and IM5-IM7 aso.)
>
>By doing this on each band, the signal you put on air will be very good.  
>It will not be possible to overdrive the PA.
>
>The IM products from Penny and Pennylane are normally >-60 to -70 dBc at  
>500mW PEP output and that is extremely good. Please do not overdrive your  
>PA and destroy this.
>
>Good luck and 73,
>Kjell
>
>
>
>
>
>
>
>På Tue, 29 Nov 2011 04:43:52 +0100, skrev Phil Harman <phil at pharman.org>:
>
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>> Bob,
>>
>> The automatic Power out calibration  function in PowerSDR does not
>> function with Penny or PennyLane - we need to talk nicely to one of our  
>> PC
>> programmers to get this changed.
>>
>> In which case the manual method is to one to use for now. I set the
>> 'Gain-By-Band' so that I get 100w out of my attached PA when the Drive
>> slider is set to 100%.
>>
>> Can't help you with the 'pop' since I don't use the LPU but very pleased
>> to hear that you are not letting the smoke out of any of the chips.
>>
>> 73 Phil...VK6APH
>>
>>
>>> ***** High Performance Software Defined Radio Discussion List *****
>>>
>>> Hi:
>>>
>>> I've been trying to calibrate my new Pennylane card HPSDR per the
>>> instructions on Page 12 of the Penelope Manual.
>>> (http://openhpsdr.ogr/wiki/images/4/4c/Penelope_manual_v_1-2.pdf)
>>>
>>> I have just installed the Pennylane card in my HPSDR Pandora which
>>> has Magister and Mercury all powered from the LPU.
>>> I installed the 17-Nov-2011 version of PowerSDR1.16 from W5WC (I
>>> prefer its look to the "skin" of PowerSDR1.19) and have
>>> no problems in receiving with Mercury. Firmware versions are 18 for
>>> Magister, 29 for Mercury and 13 for Pennylane. I am using
>>> Winows XP SP3 on an Asus based PC.
>>>
>>> I have connected a 50-ohm dummy load to the Penelope output BNC.  I
>>> have my scope connected across the load resistor so
>>> I can measure the output voltage and its frequency and look at its
>>> waveform. I do not have a microphone connected as yet.
>>> The "Drive" level is set at 100. Everything seems to perform as
>>> expected except for the output power adjustment.
>>>
>>> A problem occurs when I try to run the calibration routine in the "PA
>>> Settings" Tab as recommended on Page 12 of the
>>> referenced manual. The initial "Gain By Band" settings are all set to
>>> 49.0 dB. When I click on "Calibrate", Pennylane
>>> starts stepping thru increasing amplitude signal values at 160 meters
>>> until at the 4th step the signal begins to overdrive
>>> the output of Pennylane and the signal on the scope shows clipping.
>>> After a couple of more steps, the routine stops with
>>> an "Invalid Gain Found" message. The clipping level is just under 20
>>> volts peak-to-peak (0.5 watts). The amplitude of the
>>> output first step of the calibration measured 10v p-p on the scope,
>>> the second 15v p-p, the third 16v p-p and the 4th and
>>> following steps are heavily clipped at 18v p-p. The TX Meter "Fwd
>>> Pwr" read successively 251, 408, 624, 628......mW.
>>>
>>> After trying various settings,  I found that if I crank the "Drive"
>>> down to 4, the calibration runs without bombing. In this case
>>> the amplitude of the output remains constant as the frequency is
>>> stepped to each band in turn. However, after the calibration,
>>> the "Gain By Band [dB]" values are not changed from their initial
>>> settings as I expected they would be.
>>>
>>> Since Pennylane was checked out at IQLabs, I assume I have not set
>>> something up right but I can't figure out what it is.
>>> Or does Pennylane not work the way Penelope does?
>>>
>>> Can someone explain just what is being calibrating and how it is
>>> done. Apparently Pennylane is feeding different input signal
>>> levels into its input and is reading the output so as to set the
>>> system gain on each band to get the same output at each rf
>>> frequency. Also, what is the "Advanced Calibration Technique" that is
>>> selected by checking the box in the "PA Settings" Tab?
>>>
>>> I have found that I can do the calibration manually. For each band, I
>>> set the "Gain By Band [dB]" to 49.0 and slowly crank it down
>>> until the "Fwd Pwr" as read on the TX meter reads 500mW. This is with
>>> the "Drive" level set back to 100. This appears to work
>>> properly and gives me a consistent 0.5 watt output on each band.
>>>
>>> However, if I hold the output at 500mW for too long, I hear a "poof"
>>> from Pandora and everything goes dead!  All the red lights
>>> go out and the program stops. If I turn my power supply off and back
>>> on again, things seem to recover. I suspect maybe a fuse
>>> blowing because of excessive current drain but the total Pandora
>>> current drain including the fan only measures 1.670 amps. LPU
>>> has 2 amp fuses in both its 12 and 5-volt outputs.
>>>
>>> I have no experience with the type resettable fuse used in LPU. Do
>>> they make a noise when they blow? Are they fast acting or
>>> slow acting? They are 2-amp fuses (unless I got them mixed up) with
>>> only 1.670 amps thru them. What sort of accuracy may be
>>> expected for their blowing current? Maybe I should measure the supply
>>> current on my scope and see if there are any high
>>> transient currents. Anyone's experience on these matters would be most
>>> helpful.
>>>
>>> Thanks for any information or any ideas.
>>>
>>> 73,
>>> Bob Mahrenholz
>>> K4QQK
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
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>>
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