I don't see what might be the purpose of using an RTL dongle. It's 8bits ADC limits its dynamic range to a mere 48db or so. Otherwise tapping is a good idea. All the points you have identified might be good depending on the hardware between the uBitx and the PC. For instance if you would use just an opamp, an oscillator, a 7dbm passive mixer (no IQ, just to convert between 12 an 96khz depending on the soundcard) and an audio step up transformer the tap before the 12Mhz would perfectly make sense to me not only to have just a slightly bigger visual picture of the signals around but to use the PC as the main receiver.
Il 25/set/2018 04:07, "Joe Puma" <
kd2nfc@...> ha scritto:
I think I found a good tapping point. C215 before the filter and shield to ground. C216 seemed like there was a lot of noise, I don¡¯t think it was more signal, just more noise. C214 looked ok but had the classic dip in the center that I even see on my commercial rig when I tapped the IF. Noise floor was also higher then 215 is that what we call ¡°cruft¡±?
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Only thing is at c215 when my SDR is plugged in the audio and noise seems to drop a little. Cant say if it¡¯s a attenuated signal but there is a difference when the sdr is plugged in. maybe I need something to buffer the connection?? I use this on my FT-840
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I do have the full signal now and bot the IMD is messy. I see now why I hear AM stations everywhere on 80 and 40.
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Connected to 210, check the dip to the left.
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Connected to C215
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Wider View IMD = Yuck, ??BCI filter is Next!
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Joe
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Sent from for Windows 10
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When used in matched pairs, the dots should be together.
