• DJ7TH Hi Rolf,

    I guess that the strong signal near 2708 MHz is just an artifact resp. alias, similar to the birdies on an analogue receiver.

    It also disappears, for example, if you set the SA to a center frequency of 2408 MHz.

    Reducing then the span step by step from 61 down to 33 Mhz, again, our spurious signal moves from right to left through the spectrum.

    At 32 MHz span it has reached 2407.8 Mhz once more, at 31 MHz span it disappears miraculously...

    But it gets more interesting.

    At 2408 MHz I have permanently a smaller signal with about 10...15 dB above the noise floor,

    independent of span and center frequency.

    However, this signal also disappears completely if a span of 3 MHz or less is set.

    73 de Roland

  • DM5RM Hi Roland,

    yes, very mysterious things are already happening inside Pluto. It would be interesting to know whether a commercial SA produces the same results and which spurious waves are actually generated by Pluto. In my 2.4GHZ-PA, a multi-circuit filter ensures the suppression of secondary waves, but only if they are outside the passband 8)

  • Please always keep in mind that the Pluto is a digital piece of equipment (key word: aliasing) and is 140 USD only.. there is a reason why real spectrum analysers are much more expensive. That said, once you recognize its limitations it is a great piece of hardware.

  • Hi all,

    some of the undesired components and images are derived from combined of nearby local oscillators RX and TX; unfortunately, this is a lack of the transceiver of Pluto as confirmed by ADI. These undesired components are not present at some span settings because the LO RX turns in sweep tuned mode, and they are out of scope of the chunks. Keep in mind that this behavior is mainly due to using RX and TX in loopback configuration with nearby LO.

    73 Alberto