Re: zBitx +-2 MHz transmit spurs? --> SHOWSTOPPER for transmitting
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Jeorg,? Please describe your set-up and monitoring cabling, antenna etc,l BSEE, ? AASEET, ? FCC Lic.# PG-18-19178, ? KG9H Electronic Instrument Associates?- Central, Inc. ...since 1971 w:???d/l our linecard at???
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On Apr 16, 2025, at 11:36?AM, Joerg DB2OO via groups.io <db2oo.ju@...> wrote:
? To be on the safe side, I tested it with a lab supply as well as with 18650 batteries:
Same result, the +/- 2.x MHz spurs are there with both types of power supplies!
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I think the spurs are originating in the SI5351/MS5351, which has to deliver much more power than in the sBitx, which has low oscillator power demand, due to buffer amplifier for the 40MHz and high impedance input of the KISS-Mixer.
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The only band, where I did not see them is 80m, where the output seems to be clean.?
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On Wed, Apr 16, 2025 at 10:00 AM, <Vu3vwr@...> wrote:
Joerg,
Are you running the tests with batteries or are you using an SMPS to power the radio during the test? 2MHz is a common switching frequency and as Wojtek suggests, the issue maybe the PS.
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I have raised this with Farhan and will wait for him to chime in on this after he has a look.?
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73,
Ragav
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73, Joerg - DB2OO
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de KG9H
Life member, ARRL
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