Bill Most certainly, especially if it adds components or any sort of tweaks to eliminate or reduce ground loops add filtering or whatever would customize it more than the external box.
Tony has already said he could produce a board which could possibly fit in a 15 pin backshell. Am most definitely interested. I think in the all in all, the Delta 44 is probably the best compromise. Eric -----Original Message----- From: Bill Guyger [mailto:[EMAIL PROTECTED] Sent: Friday, August 05, 2005 12:18 AM To: [EMAIL PROTECTED]; FlexRadio@flex-radio.biz; [EMAIL PROTECTED] Subject: Re: [Flexradio] Delta 44 Breakout Box and Balanced audio Eric I have a drawing of exactly what you are asking for. Its in PDF form and I'll be glad to send it to you. I can also send it in Visio (.vsd) or Autocad (.dwg) format if you desire. At least one other list member is using my breakout box / ground loop eliminator, and is happy with the results. Bill AD5OL >>> "ecellison" <[EMAIL PROTECTED]> 08/04/05 10:43PM >>> Don Yea!!! Thanks for the information! I have Tony * KB9YIG awaiting a word to go ahead with 15 pin connector board kits to interface directly to the Delta 44 with 1/8 inch stereo cables or jacks. without external box etc. I have a mass of wires running all over the place with infernal ¼ inch connectors, and in the long term plans that just ain't gonna cut it. ¼ inch is fine for guitars which don't go on DXpeditions, but there is a limit to 1930's audio connectors! I know you are making a different point here, however, would love it if you would consent to a drawing of the components you mention. Any ideas for filtering and isolation would also be appreciated. I think many folks will go the Delta 44 / 66? Route. For anyone who is reading, Tony is also specing out a serial port to paddle circuit board with 1/8" stereo connection for CW which I'll produce and 'market'. Thanks Eric _____ From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Don Newberry Sent: Thursday, August 04, 2005 11:25 PM To: FlexRadio@flex-radio.biz Subject: [Flexradio] Delta 44 Breakout Box and Balanced audio Hello all, I was considering using a DB 15 connector, appropriate plugs and shielded cable to interface between the SDR and the Delta 44, bypassing the breakout box altogether. I thought this would make a little cleaner setup here (not that this has mattered much before, hi). I traced out the wiring inside the box to find out the pinouts for the various ins and outs, and will list them below. One interesting thing that I found was how M-Audio implements Balanced or Unbalanced configurations. As you may know, they allow balanced audio ins and outs by using both the Tip and Ring, with the shield tied to the sleeve, But it appears that they are not using a true Balanced input at the sound card. The Ring connection simply terms. into a 10k resistor in series with a 22u cap to common, while the Tip continues on to the sound card input. The outputs are sim., the Ring is tied to common through a 130 ohm R and series 22u cap, while the Tip carries the actual output. I suppose these components match the Z values on tip and ring as they appear to external equipment, but there is no signal present or used by the Ring half of the line. In the past, there was some talk of using balanced I/Q signal paths between the SDR and Sound card, to gain noise cancelation and s/n improvment at the sound card. This is a step up from our current unbalanced method. Seems like M-Audio is defeating any advantage of using balanced lines, even if a new SDR incorporated them. I wonder if the Delta 44 is typical of other higher end "Pro" sound cards? Just something you might want to keep in the back of your mind for future use. Anyway, here are the breakout box pinouts: TRS Jack DB15 pin In 1 tip..............13 In 1 ring.............term'd (Input ring terminations are 10k in series with 22uF to sleeve) In 1 Sleeve........14 In 2 tip..............6 In 2 ring............term'd In 2 sleeve........14 (Input 1 and 2 sleeves are tied together) In 3 tip..............15 In 3 ring............term'd In 3 sleeve........7 In 4 tip..............8 In 4 ring............term'd In 4 sleeve........7 (Input 3 and 4 sleeves are tied together) Out 1 tip..........1 Out 1 ring.........term'd (Output ring terminations are 130ohms in series with 22uF to sleeve) Out 1 sleeve.....9 Out 2 tip..........2 Out 2 ring.........term'd Out 2 sleeve.....9 (Outs 1 and 2 sleeves are tied together) Out 3 tip..........3 Out 3 ring........term'd Out 3 sleeve....11 Out 4 tip..........4 Out 4 ring........term'd Out 4 sleeve....11 (Outs 3 and 4 sleeves are tied together) Pins 5, 10 and 12 are not used. Pins 14, 7, 9, and 11 (sleeves) are grounded at the sound card's ground plane 73 and gn Don, wd4egf
