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1-3 of 3 messages
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PSK Interface problems
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by N0YAX on October 15, 2009
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Hey Everyone!
I finally got my soundcard interface in today, and hooked it up for my first foray into the world of PSK31. Still trying to figure out how to set all the dials and stuff, but one weird thing was happening - when trying to use the Serial interface to transmit, the radio never fully shifted to transmit mode. I'll start off with my Hardware:
Radio: IC-730
Computer: Acer Aspire One
Interface: Custom made by Associated Radio in Kansas City, specific for the 730
Since the Aspire One has no hardware serial port, I'm using a USB->Serial adapter by Sabrent, purchased from Newegg:
http://www.newegg.com/Product/Product.aspx?Item=N82E16812156003&Tpk=SBT-USC1K
I read reports of this adapter working well for PTT function on PSK31 for machines with no serial port, and the price was right, so I got it as well.
Using Digipan, when I have the software try to transmit, the audio from the radio does go silent, I do hear the click I normally hear when I push the mic button, but the transmit light never comes on, and there's no RF being transmitted according to my watt meter. The interface connects thru the accessory connector, not the mic jack, and in fact, the mic was completely disconnected while I was testing earlier. I grabbed the interface and compared the accessory plug with the pinouts shown in the manual, and it looks right to me, but the transmit failure puzzles me. I'm thinking about trying again, but this time using one of my computers that actually has a real serial port.
When I shift the radio into VOX mode, I do put out a signal, but at very low power levels (only about 10-15 watts out according to my watt meter). I know you're not supposed to drive at full power with PSK31, but surely I should be able to get 30-40 out. This is with the RF PWR dial at about half, the mic gain a little below half, and the volume controls on the computer almost all the way up. I'm new to the mode, so right now my #1 concern is wanting to make sure I have everything configured right so I'm not causing a bunch of splatter.
I know I was getting out, as I can see my call appearing on the psk.gladstonefamily site. But I never had much luck getting an answer to my CQ's.
So, I guess my question is two-fold:
1. Any ideas on the oddness in the PTT function?
2. Can anyone out there give me a quick run-down on exactly what to look for to ensure my signal is clean?
Thanks!
Jeremy, N0YAX
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RE: PSK Interface problems
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by WB5JEO on October 16, 2009
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The short form of clean signal set-up is essentially (into dummy load or dead part of the band)use the volume slider with the Mode set to TUNE and see what your normal output power is. ALC level should naturally be high at that time. Set Mode to transmit and use the volume slider to drop the volume out until the ALC quits working or nearly quits. Power should be well down at that point. The best check, of course, is to monitor your signal or have someone else monitor it and report your IMD, which should be in the -20 somethings and a waterfall display consistent with that, showing only faint sidebands or none.
I don't think that power out you're showing is unreasonably low for where you set your RF power. (It's really not a matter of power causing problems, although the rule is always minimum power to do the job. It's how you're driving it. Your only concern with power is whether your rig can handle it at 100% duty cycle.) You definitely got copied coast-to-coast during both sessions on 40.
But you shouldn't have to run the volume slider that high. Try playing the Wave slider to see if you can get the highest power without ALC coming in with the Volume slider at about half scale. (Volume and Wave should be unmuted and all other controls muted.) If that fixes it, go back through setting it all up, since you'll probably be overdriving then. I don't know enough about the 730 to say if it's an issue with the radio creating the no signal with PTT run through the accessory socket.
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RE: PSK Interface problems
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by VA7CPC on October 19, 2009
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If the rig-to-soundcard interface is going into the IC-730 microphone input:
I believe that the IC-730 has really low mic sensitivity. You might need either more audio drive from the computer, or an adjustment to a voltage divider in the interface.
If you can bring up the Windows Mixer, there are two sliders you have to adjust. One is the "master gain" control (the left-most slider), the other is the "Wave" slider. The "master gain" control is duplicated in the "Volume" control (the loudspeaker icon on the Windows taskbar).
To get full output from the soundcard, _both_ sliders should be at the top of their range.
Many PSK31 programs (including Digipan) let you adjust the "Wave" slider from within the program. But they don't let you adjust the "master gain" control.
Charles
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