in the last few days I've been evaluating a couple of low cost audio to USB interfaces for use primarily with digital modes -- RTTY, PSK, JT65, FSK441. My primary objective is to improve decode performance at low signal levels. I studied the catalogs and chose two low cost units that looked like they would do the job and would not have RF problems.
Here's a link to a little Numark adapter that I bought for $33. t's as cute and easy as it looks. Power from the computer, a couple of RCA to 1/8-in cables for gozinata and gozouta. http://www.bhphotovideo.com/c/product/639303-REG/Numark_STEREO|IO_Stereo_iO_USB.html The other one I bought is this Tascam unit. A bit larger, more mechanically robust, mostly metal enclosure, more flexible with respect to levels. The 1/4-in jacks for guitar and mic have more gain, so will work with lower signal levels. $70 http://www.bhphotovideo.com/c/product/648495-REG/Tascam_US_100_US_100_USB_2_0_Computer.html To evaluate them I hooked them to different Thinkpads running JT65-HF and fed both of them from the line of a K3, then compared their decode performance, and also compared them with the Thinkpads' internal sound card. The two new adapters performed equally well, and often produced almost twice as many decodes on a given pass as the the internal cards. Next I transmitted through them and looked at their spectrum on a P3 hooked up to a second K3. Distortion products look minimal on both units. I also pulled them apart and studied their construction. Both use proper construction that avoids the Pin One Problems that cause RFI issues. Now that I'm sure that they work well, I'm rewiring my station to use them in place of the sound cards built into my Thinkpads for SO2R contesting and everyday digital operation on both HF and VHF. Both of these units are a real bargain from well known audio vendors. Their interface to the K3 (and other rigs) is really simple. They don't do any control functions, so you still need a serial or USB to serial for that. I use VOX to key the K3. Both are available from other vendors, but B&H had the best prices I found, and shipping by UPS Ground was free. 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
