Known Internal Spurs

Is there a list of internal spurs for the receiver. Is there something at 1000 KHz?


  • I checked here and indeed there is a steady carrier on 1 MHz in my Kiwi.
  • jksjks
    edited March 2017
    There is no documented spur list.

    If I disconnect the HF input on mine (or terminate in 50Z) the only spurs I get are the GPS clock at 16.368 MHz at about S1 in USB or CW mode. The rest of the noise floor is completely flat 0 - 30 MHz at a little below S3 in AM and a little below S1 in U/LSB. That of course is far from the full story.

    I don't believe there is any problem on 1000 kc. I looked at your Kiwi. Could it just be WMVP-HD leaking a little carrier? -80 dBm wouldn't be very much with that much power going into the USB from the looks of it. Their LSB suppression doesn't seem all that good unless that is intentional for some reason.

    Or maybe it's a co-channel carrier. It was 1900 local when I looked and the carrier varied from -75 to -95 dBm. A fading carrier like that is usually not a spur. Oh yeah, I just listened to 1000 kc now in CWN and it was pulsing at around 0.3 Hz. That is a classic sign of multiple co-located AM station carriers beating against each other. Now it's back to being steady with a very, very slight pulsing. Bring up the S-meter extension to see the pulsing graphed as a function of time.

  • I have stable signals on my kiwisdr on (khz):
    1104, 3312, 4416, 5520, 6624, 8832, 9936, 12144, 13248
    17664, 20976, 23184, 24288, 25392 and 26496

    It looks as if the 1104 khz is the main frequency and the others are multiple of 1104 khz, hm?
  • I have only weak 1104
  • With the antenna disconnected the noise floor is relatively flat at around -105dB and I see NO obvious spurs at all.

    When the antenna is connected I do notice a slight difference when the Micro USB port is connected to a PC, but nothing else.

    I have an RF choke on the Ethernet cable (12  turns on FT240-31 ferrite core) near the KiWi to minimise noise that could be carried by the network cable.

    Some noise can be induced into the KiwI from other nearby electronic equipment if has a strong magnetic RF field, for example if it includes a switching power supply or DC-DC convertor. You can test for this by disconnecting the antenna and moving the Kiwi around to see if the spurs change in level.


    Martin - G8JNJ
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