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

Tue Nov 29 10:42:21 PST 2011

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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