Special Treatment For SDR Receiver

Discussion in 'Software Defined Radio (SDR)' started by WQ4G, Sep 6, 2020.

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  1. WQ4G

    WQ4G Ham Member QRZ Page

    Greetings to all:

    Does the SDRplay RSP1A need any special protection from RF, such as grounding out the center conductor of the coax connector, to protect it from my transmitters? I know about the RSP1A limits if I were transmitting into it. But, what about when I am TXing on my HF rig at 100 watts? Or when I use my amp at 600-700 watts?

    Also, do I need to be cautious/conscious about where I place the thing in my shack? Do I need to keep it away from the amp? Or can I lay it on top of the amp?


    Dan WQ4G
  2. K6CLS

    K6CLS Ham Member QRZ Page

    I haven't had any trouble with stray RF in my RSP1A. I'm careful about common mode.

    But put ferrites on both ends of the USB cable.

    And yes, protect it from TX signals. Eithwr with a coax relay,.or a separate receive antenna, situated a good distance from the transmitting antenna.

    I'm curious, what software will you use?
  3. HB9PJT

    HB9PJT Ham Member QRZ Page

    When you have the RSP1A connected to an antenna which is near the transmit antenna then too much RF might come to the RSP1A. I measured once 5% of the transmit power when I connected the power meter and a dummy load to the RX antenna. Depending on the band. When you use a SDR switch like the MFJ 1708B then the SDR does not have a problem.

    73, Peter - HB9PJT
    N0CEL likes this.
  4. WQ4G

    WQ4G Ham Member QRZ Page

    Well, that's a good question. I have down loaded and tried SDRuno, HDSDR, and SDR Console. I like SDRuno because it seems more familiar (like an old school radio), but I have been using SDR Console more. I want to eventually start using the RSP1A to hunt RFI with and Console seems more useful in that respect. So I have been concentrating my effort on familiarizing myself with SDR Console.

    I don't plan to use the RSP1A as my main station receiver any time soon. So it won't be hooked up to any antenna while I am transmitting. But, I need to find a permanent place for it to reside in my shack and I am concerned about it's proximity to my HF rig, Amp, VHF equipment, and transmitting antennas.


    Dan WQ4G
  5. N9LCD

    N9LCD Ham Member QRZ Page

    I wouldn't trust any switch until I verified that there was no leakage between ports. I had leakage at "receive only" levels with a mechanical switch until I separated everything!
    WQ4G likes this.
  6. KA9JLM

    KA9JLM Ham Member QRZ Page

    It is all about timing.
  7. G8GYW

    G8GYW Ham Member QRZ Page

    I have an RSPdx on my desk next to my 100W transceiver, and they are connected to the same antenna via a MFJ-1708-SDR switch.

    The SDR is perfectly happy.

    KK4NSF likes this.
  8. KA9JLM

    KA9JLM Ham Member QRZ Page

    That is good.

    I think that model is up to version 3. It took 3 tries for them to get it right.
  9. HB9PJT

    HB9PJT Ham Member QRZ Page

    Only 2 generations are known to me. But there are 2 variants with different functionality in both generations. Many other companies do not touch this topic. There are only few alternatives and MFJ is perhaps the best solution.

    73, Peter - HB9PJT
  10. KK4NSF

    KK4NSF Ham Member QRZ Page

    That's the exact same set-up I have, and it's worked well for several years now. The only thing I'd add is that I have my switch grounded. I don't know if that helps, but it can't hurt.

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