I have one variant similar to signalink. Is a Cat/data interface Sm4xiu.?
Yes, is a possiblity that the isolation transformers, can be a source of problems. But now I jumpered it. I have made new tests, and I obtained connections ok, at speed of 7200 bauds in the UZ7HO highspeed sound modem ( with the rig in 9600 mode ). But no at 9600.?
I have good rx, but no TX.
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Caution: the 857 rig have two rx outputs in pkt mode: One pin? for rx in 1200 and other pin rx pin 9600, in data connector. And only one pin for tx in 9600 and 1200. Yes I put a swtich for switching audio 9k6 to 1k2.
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I suspect that the problem is that my usb sound cards (? I? am trying two models ) have a line level output sufficient for 1k2, but? with very low level of signal for 9k6. In fact one of the two have a little more high level than the other.
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I see in the rig with mod indicator at the display, the better sound card, only comes to 1/4 of the modulation scale of the meter.?
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Looking the cat port radio specs. I see the tx input of the rig, have a signal of 1Vpp 10k Zin. I suspect that in general the usb sound cards line level don't have this level of signal. I will measure later, with a oscilloscope the level of signals.
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If this suspect is correct I will contruct a little preamplifer for example with operational amplifer ( non inverter amplifier with single power supply with variable gain).?
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73's? ? ?
