Hi Alberto! >I would say that probably the culprit is the QSD, rather than the >sound card. With Winrad, being careful in tweaking the Fine controls, >I have been able to reach even 110dB of attenuation of the image. But >when you are at this level, just blow on your QSD hardware, and you >will see that value deteriorate up to 80dB or even worse... and, in >addition, 110dB are obtained just at a single point of the range. From >tests I have performed, with a calibration about at mid scale, what >you can obtain is a rejection that goes up to about 50dB at the two >scale ends. This is a value that many could consider acceptable. >But of course you must start first with a hardware that is reasonably >balanced by itself. > >73 Alberto I2PHD >
Well this, of course, wasn't something I wanted hear, hi. The desing for the receiver side is basically the same as can be found from the "software defined radio for the masses" part 1, expect I have a dual balanced QSD. Some pics of the board can be found at www.oh1gtf.com under the "SDR HF transceiver with DDS", just to show you the design. The reason why I originally thought the problem might be in the soundcard, is due few stories I found about E-mu soundcards working with SDR (flexradio I think). Here's one: http://www.productionforums.com/viewtopic.php?t=1738&sid=6d7731ffe8e67095fa6a43c7335a2ccc It would unfortunate to make new desing because the receiver, but if this is the case, then it has to be done :) I thought that copying a commercial desing would haved worked! I should propably test with somekind of external soundcard (USB), wouldn't it tell either the fault is in souncard or QSD? 73 de Janne Pulkkinen, OH1GTF
