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Author Topic: Monitoring PSK31 signal output  (Read 5737 times)
N8EUI
Member

Posts: 146




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« on: January 17, 2013, 12:49:55 PM »

Hi all,
I recently acquired a very clean Yaesu YO-301 monitor scope in excellent working order.  Just wondering, can this scope be used to visually monitor the quality of my PSK31 signal output?  I have it setup to monitor my SSB transmissions.  Conventional wisdom would have it PSK31 transmissions can be monitored, too.  Correct?

Thanks,
Tom, N8EUI
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N8FNR
Member

Posts: 130




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« Reply #1 on: January 18, 2013, 06:03:00 AM »

Don't know about using your scope but I have a Flex-5000 and we are told to just keep the ALC below -1 and there is no mention in the instructions about using the scope built into the rigs software.

On the otherhand I have an IMD Meter by KK7UQ and it works great. It is well worth the cost ($140).

Zack
N8FNR

IMD Meter by KK7UQ
http://www.navigator-interface.com/naviusa_010.htm
"The IMD Meter by kk7uq is by far the best, easiest and most accurate way to monitor your own transmitted PSK IMD.   The IMD Meter displays your transmitted BPSK31/63 or QPSK31/63  IMD in real time on an easy to read 3 digit LED panel.  There are absolutely no connections to your radio, coax or PC. The IMD Meter by kk7uq is a true stand-alone IMD Meter."

Ther are 28 eham reviews all are 5. http://www.eham.net/reviews/detail/4210
« Last Edit: January 18, 2013, 06:07:46 AM by N8FNR » Logged
AA4PB
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Posts: 12667




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« Reply #2 on: January 18, 2013, 06:39:38 AM »

An idling PSK31 signal will look like a two-tone test signal on the monitor scope. The problem is that it takes a pretty fair amount of distortion to be seen visibly on the scope. A second receiver or a PSK-meter is a much more accurate method of determining IMD levels on a PSK31 signal.
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N8FNR
Member

Posts: 130




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« Reply #3 on: January 22, 2013, 09:10:27 AM »

Here is another external way to measure your PSK signal. I had one of these and used it with a TS-850 before I sold both. It was a very easy kit to build and it worked very well. The price is $50.00. It is rated 3.6/5 on eham but I would have given it a 5 myself. http://www.eham.net/reviews/detail/3347

http://www.ssiserver.com/info/pskmeter/

Zack
N8FNR
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K0YQ
Member

Posts: 436




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« Reply #4 on: January 22, 2013, 11:19:01 AM »

Don't know about using your scope but I have a Flex-5000 and we are told to just keep the ALC below -1 and there is no mention in the instructions about using the scope built into the rigs software.

On the otherhand I have an IMD Meter by KK7UQ and it works great. It is well worth the cost ($140).

Zack
N8FNR

IMD Meter by KK7UQ
http://www.navigator-interface.com/naviusa_010.htm
"The IMD Meter by kk7uq is by far the best, easiest and most accurate way to monitor your own transmitted PSK IMD.   The IMD Meter displays your transmitted BPSK31/63 or QPSK31/63  IMD in real time on an easy to read 3 digit LED panel.  There are absolutely no connections to your radio, coax or PC. The IMD Meter by kk7uq is a true stand-alone IMD Meter."

Ther are 28 eham reviews all are 5. http://www.eham.net/reviews/detail/4210

Universal Radio has had a KK7UQ IMD meter on their used list for awhile now at $80.  Great little gadget for PSK... 
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AD6KA
Member

Posts: 2232




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« Reply #5 on: January 23, 2013, 12:13:30 AM »

Here is another external way to measure your PSK signal.
<snip>
http://www.ssiserver.com/info/pskmeter/Zack, N8FNR

The PSK Meter is pretty nifty. From their site:
...... a microprocessor-based RF signal sampler that periodically
checks your RF output, computes its IMD locally, and
automatically sets the sound card's audio level to provide the
highest RF output with minimum distortion.

I too like the PSKMeter, because:
1) I can read the IMD and waveform right there on
     the computer screen in another window.
      Or the same window if things are resized.

2) It automatically adjusts the audio level.
    So it's a meter AND fixes any drive level problem.
    No more messing around with Windows Audio Sliders
       or tiny pots on interface boxes!


However.....
The KK7UQ IMD Meter has an advantage in that you
don't have to hookup anything to the rig or hookup anything
to the computer. Sometimes less gizmos and wires
to hookup is better.

There's a place for both, it's a matter of preference.
73, Ken  AD6KA
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KA2UUP
Member

Posts: 388




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« Reply #6 on: January 23, 2013, 06:28:55 AM »

The PSKMETER is a godo product. However, the problem is that the software may not work with Windows 7.  For clean PSK signal, do the following:

1)  Put the radio in CW and adjust for a signal output of 50 Watts
2)  Change to SSB and tune your PSK signal so that the ALC indication is zero.

This should give you an output of about 25-30 Watts, more than enough for PSK31 and within the IMD limits.  I use a Kenwood SM-220 station monitor and it is useful in monitoring the output.

Good luck!

Bert, KA2UUP
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N7WE
Member

Posts: 13




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« Reply #7 on: January 23, 2013, 08:40:20 AM »

I too am a fan of the IMD Meter.  Quick, easy, no connection, visible number, and audible alarm if things go wide.  If the IMD meter is about 30, no ALC showing on the rig, and power about 25w, you know you are clean.  The world of PSK would be a better place if everyone had this meter in their shack.  Well worth the money, but sure wish you could still buy it as the kit!

Also, if you can have someone take a screen capture of your signal on their waterfall and email it to you - that's the ultimate check!  Super easy to do if you are running HRD/DM780. 

Rick - N7WE
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AD6KA
Member

Posts: 2232




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« Reply #8 on: January 24, 2013, 03:10:50 PM »

Quote
KA2UUP:
The PSKMETER is a good product. However, the problem is that
 the software may not work with Windows 7.

Good point! I've found LOTS of ham software that
won't run, or run properly with WinBlows 7.
Sometimes the fix can be as simple as using
a FTDMI chip USB/Serial cable, other times nothing works.
73, Ken  AD6KA
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