PSK31 Power Level
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Elecrafters,
Don has been coaching me off-list through installation of one of his fixed audio output kits, which I've had around here for many months, un-built. All went well, except the audio through my computer was distorted. I eventually tracked it down to the K2 DSP gains being set too high. I was getting away with that in the basic K2, but the fixed audio unit doesn't like being pushed that hard. I've now carefully reset the DSP gains to get the same audio level with DSP and with DSP bypassed. Everything is working great. I'm now reminded of a nagging question since the last time I strayed from CW to PSK 31. I've read numerous places about setting the power level (mine is a QRP K2) to five watts for continuous use like PSK. Does that mean five watts for single tone like CW, or five watts average as the two tones warble back and forth? I'm using a WM-2 wattmeter in the output. Running about 10 watts single tone, I get about five watts warbling and a single ALC bar flickering. Is this okay, or should I back it down to five watts single tone? I thought this question might be of interest to a wider audience. Parker WD8JOL K2 #2636 ...back to work tomorrow, and peace for Don. _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Parker,
The best for running PSK31 is to set the power knob to 10 watts or above. Then adjust the level from your computer soundcard so your power meter goes up to 5 watts with the idle tone. There should be no ALC bars showing. Also, be certain that you have the compression set to 1:1. If you are using the RTTY mode, there is a separate SSBCr setting in the menu, and that is independent of whatever compression level you may be using for SSB. If you are using the RTTY filters, remember that there is yet another set of 4 filters that need to be properly set up for width (use the OP1 filter for FL1 - that is important), and set the remaining filters whereever you would like in terms of width and filter center. Use Spectrogram and it is easy. If you want to increase the gain for the KDSP2 again for whatever reason, you may have to add a divider at the two inputs of the Fixed Audio board - something like 2.2k in series and then 2.2k to ground should give you good results. 73, Don W3FPR -----Original Message----- Elecrafters, Don has been coaching me off-list through installation of one of his fixed audio output kits, which I’ve had around here for many months, un-built. All went well, except the audio through my computer was distorted. I eventually tracked it down to the K2 DSP gains being set too high. I was getting away with that in the basic K2, but the fixed audio unit doesn’t like being pushed that hard. I’ve now carefully reset the DSP gains to get the same audio level with DSP and with DSP bypassed. Everything is working great. I’m now reminded of a nagging question since the last time I strayed from CW to PSK 31. I’ve read numerous places about setting the power level (mine is a QRP K2) to five watts for continuous use like PSK. Does that mean five watts for single tone like CW, or five watts average as the two tones warble back and forth? I’m using a WM-2 wattmeter in the output. Running about 10 watts single tone, I get about five watts warbling and a single ALC bar flickering. Is this okay, or should I back it down to five watts single tone? I thought this question might be of interest to a wider audience. Parker WD8JOL K2 #2636 …..back to work tomorrow, and peace for Don. -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.446 / Virus Database: 268.18.3/700 - Release Date: 2/24/2007 8:14 PM _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Parker Buckley
I am glad Parker asked the question. I have a k2/100 and for PSK have been
setting the power level at 25 watts as displayed on the K2 readout. I do have a small blower mounted under a shelf over the K2/100---probably not necessary, but, as we all know, heat is the culprit for reducing MTBF's. Also, why should there be any difference in power out for single tone or a PSK signal? Thanks, Don, for your comments. 73, Lowell, W5FH ----- Original Message ----- From: "Parker Buckley" <[hidden email]> To: "W3FPR - Don Wilhelm" <[hidden email]>; <[hidden email]> Sent: Sunday, February 25, 2007 5:02 PM Subject: [Elecraft] PSK31 Power Level > Elecrafters, > > > > Don has been coaching me off-list through installation of one of his fixed > audio output kits, which I've had around here for many months, un-built. > All went well, except the audio through my computer was distorted. I > eventually tracked it down to the K2 DSP gains being set too high. I was > getting away with that in the basic K2, but the fixed audio unit doesn't > like being pushed that hard. I've now carefully reset the DSP gains to > get > the same audio level with DSP and with DSP bypassed. Everything is > working > great. I'm now reminded of a nagging question since the last time I > strayed > from CW to PSK 31. I've read numerous places about setting the power > level > (mine is a QRP K2) to five watts for continuous use like PSK. Does that > mean five watts for single tone like CW, or five watts average as the two > tones warble back and forth? I'm using a WM-2 wattmeter in the output. > Running about 10 watts single tone, I get about five watts warbling and a > single ALC bar flickering. Is this okay, or should I back it down to five > watts single tone? I thought this question might be of interest to a > wider > audience. > > Parker > > WD8JOL K2 #2636 > > > > ...back to work tomorrow, and peace for Don. > > > > > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.5.446 / Virus Database: 268.18.3/700 - Release Date: 2/24/2007 > 8:14 PM > > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Don Wilhelm-3
Don,
It's that "idle tone" that I question. If I push the Tune button (Digipan) I get a single tone. If I push the T/R button, I get a dual warbling tone which gives about half the reading on the wattmeter (probably something like an average of the two warbling tones and some off period between them). So you're saying to bring up the single tone to only five watts? That puts the warbling tone down to the 2-3 watt level. I guess the peaks are probably hitting the five watt level, but the meter can't keep up. Thanks, Parker _____ From: Don Wilhelm [mailto:[hidden email]] Sent: Sunday, February 25, 2007 6:23 PM To: Parker Buckley; W3FPR - Don Wilhelm; [hidden email] Subject: RE: PSK31 Power Level Parker, The best for running PSK31 is to set the power knob to 10 watts or above. Then adjust the level from your computer soundcard so your power meter goes up to 5 watts with the idle tone. There should be no ALC bars showing. Also, be certain that you have the compression set to 1:1. If you are using the RTTY mode, there is a separate SSBCr setting in the menu, and that is independent of whatever compression level you may be using for SSB. If you are using the RTTY filters, remember that there is yet another set of 4 filters that need to be properly set up for width (use the OP1 filter for FL1 - that is important), and set the remaining filters whereever you would like in terms of width and filter center. Use Spectrogram and it is easy. If you want to increase the gain for the KDSP2 again for whatever reason, you may have to add a divider at the two inputs of the Fixed Audio board - something like 2.2k in series and then 2.2k to ground should give you good results. 73, Don W3FPR -----Original Message----- Elecrafters, Don has been coaching me off-list through installation of one of his fixed audio output kits, which I've had around here for many months, un-built. All went well, except the audio through my computer was distorted. I eventually tracked it down to the K2 DSP gains being set too high. I was getting away with that in the basic K2, but the fixed audio unit doesn't like being pushed that hard. I've now carefully reset the DSP gains to get the same audio level with DSP and with DSP bypassed. Everything is working great. I'm now reminded of a nagging question since the last time I strayed from CW to PSK 31. I've read numerous places about setting the power level (mine is a QRP K2) to five watts for continuous use like PSK. Does that mean five watts for single tone like CW, or five watts average as the two tones warble back and forth? I'm using a WM-2 wattmeter in the output. Running about 10 watts single tone, I get about five watts warbling and a single ALC bar flickering. Is this okay, or should I back it down to five watts single tone? I thought this question might be of interest to a wider audience. Parker WD8JOL K2 #2636 ...back to work tomorrow, and peace for Don. _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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It has been a while since I did PSK, but I believe the driving factors
for his statement has to do with duty cycle and output power. Since PSK is at a higher duty cycle (the PA is effectively transmitting more power over a longer time) that they suggest you reduce the power to reduce the effect on the PA's and associated circuitry. As an example, all the lasers that are carrying the bits and packets on the optical backbone to the Internet, all use "Manchester coding". Where a 1 or 0 is represented by either a square wave shifting high, or shifting low. Instead of just a high or low. That way the transmitter is at low power for half of every cycle. There by reducing the duty cycle, and the demand on the system by half. David Wilburn [hidden email] K4DGW K2 #5982 Parker Buckley wrote: > Don, > > > > It's that "idle tone" that I question. If I push the Tune button (Digipan) > I get a single tone. If I push the T/R button, I get a dual warbling tone > which gives about half the reading on the wattmeter (probably something like > an average of the two warbling tones and some off period between them). So > you're saying to bring up the single tone to only five watts? That puts > the warbling tone down to the 2-3 watt level. I guess the peaks are > probably hitting the five watt level, but the meter can't keep up. > > > > Thanks, > Parker > > > > _____ > > From: Don Wilhelm [mailto:[hidden email]] > Sent: Sunday, February 25, 2007 6:23 PM > To: Parker Buckley; W3FPR - Don Wilhelm; [hidden email] > Subject: RE: PSK31 Power Level > > > > Parker, > > > > The best for running PSK31 is to set the power knob to 10 watts or above. > > Then adjust the level from your computer soundcard so your power meter goes > up to 5 watts with the idle tone. There should be no ALC bars showing. > > > > Also, be certain that you have the compression set to 1:1. If you are using > the RTTY mode, there is a separate SSBCr setting in the menu, and that is > independent of whatever compression level you may be using for SSB. If you > are using the RTTY filters, remember that there is yet another set of 4 > filters that need to be properly set up for width (use the OP1 filter for > FL1 - that is important), and set the remaining filters whereever you would > like in terms of width and filter center. Use Spectrogram and it is easy. > > > > If you want to increase the gain for the KDSP2 again for whatever reason, > you may have to add a divider at the two inputs of the Fixed Audio board - > something like 2.2k in series and then 2.2k to ground should give you good > results. > > > > 73, > > Don W3FPR > > -----Original Message----- > > Elecrafters, > > > > Don has been coaching me off-list through installation of one of his fixed > audio output kits, which I've had around here for many months, un-built. > All went well, except the audio through my computer was distorted. I > eventually tracked it down to the K2 DSP gains being set too high. I was > getting away with that in the basic K2, but the fixed audio unit doesn't > like being pushed that hard. I've now carefully reset the DSP gains to get > the same audio level with DSP and with DSP bypassed. Everything is working > great. I'm now reminded of a nagging question since the last time I strayed > from CW to PSK 31. I've read numerous places about setting the power level > (mine is a QRP K2) to five watts for continuous use like PSK. Does that > mean five watts for single tone like CW, or five watts average as the two > tones warble back and forth? I'm using a WM-2 wattmeter in the output. > Running about 10 watts single tone, I get about five watts warbling and a > single ALC bar flickering. Is this okay, or should I back it down to five > watts single tone? I thought this question might be of interest to a wider > audience. > > Parker > > WD8JOL K2 #2636 > > > > ...back to work tomorrow, and peace for Don. > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Parker Buckley
Parker,
Use the idle tone and look at the LED on the K2 - its response time should be much shorter than your other meter. Set the display to RF and you should see the output level. The TUNE from Digipan is a single tone. You can use that for tuning a manual tuner, but it is not as good for determining the power level. Actually the very best way is to observe the power out on a 'scope. Go to CW and set for 5 watts (or any desired level), transmit and notice the amplitude on the 'scope - then switch to PSK31 and adjust the audio input until the PSK31 signal as the same amplitude as the CW signal was. Note the deflection on the K2 RF meter and you will know in the future where to set the audio level. All this is an effort to allow you to operate with the lowest IMD possible - by setting up in that manner, you can be confident that you will not be driving the K2 into compression at any point and your powr level should be within normal ratings. 73, Don W3FPR -----Original Message----- Don, It’s that “idle tone” that I question. If I push the Tune button (Digipan) I get a single tone. If I push the T/R button, I get a dual warbling tone which gives about half the reading on the wattmeter (probably something like an average of the two warbling tones and some off period between them). So you’re saying to bring up the single tone to only five watts? That puts the warbling tone down to the 2-3 watt level. I guess the peaks are probably hitting the five watt level, but the meter can’t keep up. Thanks, Parker ---------------------------------------------------------------------------- -- Parker, The best for running PSK31 is to set the power knob to 10 watts or above. Then adjust the level from your computer soundcard so your power meter goes up to 5 watts with the idle tone. There should be no ALC bars showing. Also, be certain that you have the compression set to 1:1. If you are using the RTTY mode, there is a separate SSBCr setting in the menu, and that is independent of whatever compression level you may be using for SSB. If you are using the RTTY filters, remember that there is yet another set of 4 filters that need to be properly set up for width (use the OP1 filter for FL1 - that is important), and set the remaining filters whereever you would like in terms of width and filter center. Use Spectrogram and it is easy. If you want to increase the gain for the KDSP2 again for whatever reason, you may have to add a divider at the two inputs of the Fixed Audio board - something like 2.2k in series and then 2.2k to ground should give you good results. 73, Don W3FPR _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Parker Buckley
----- Original Message -----
From: "Parker Buckley" <[hidden email]> > I've read numerous places about setting the power level > (mine is a QRP K2) to five watts for continuous use like PSK. For PSK & digital in general your aim must always be a pure signal, that is: * No audio compression (feed radio via the accessory or data socket), * No ALC, * No ALC, * No ALC. To ensure best linearity I suggest you set your Power level on the K2 (or any other radio) to the max, then adjust power out using the soundcard controls (some PSK programs have soundcard adjustment built-in). Although you could run 10 watts, it's essential that you monitor ALC at all times. Myself I would adjust the soundcard input so that you are running 5 watts while idling, a few more watts will not bring much improvement. FWIW when you have ALC indicated your signal will be harder to decode and you may well be wiping out the band. I've seen a FT-817 user with a PSK signal 500 Hz wide due to overdriving the radio. Simon HB9DRV _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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