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Proven: The MFJ-1708SDR Degrades your Transceiver's Performance

Discussion in 'Videos and Podcasts' started by VK3BL, Jul 15, 2018.

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  1. VK3BL

    VK3BL Premium Subscriber QRZ Page

    FACT: The MFJ-1708SDR Transmit/Receive switch will degrade your receivers' performance and significantly hurt your ability to work weak DX Stations.

    Using a Signal Generator, Oscilloscope, T Connector & Reference Grade Minicircuits ZSC-2-2+ Power Splitter, I conclusively prove the MFJ-1708SDR will hurt the performance of both your main receiver and SDR.

    Watch the video for a full explanation why, and how an antenna should be split, I recommend watching the video on youtube so you can read the description:


    I also explain how to get the most of the MFJ-1708SDR if you own one.

    73, Jarrad VK3BL
     
  2. VK3BL

    VK3BL Premium Subscriber QRZ Page

    Well there goes any incentive to be a premium subscriber next time I guess...
     
  3. N6QIC

    N6QIC Premium Subscriber QRZ Page

    What video?
    Please post a link to your video.

    Thanks,
     
    VK3BL likes this.
  4. N5RFX

    N5RFX Ham Member QRZ Page

    I think you need to change the title of your you tube video. Be nice.

    73,
    Mark N5RFX
     
    VK3BL likes this.
  5. VK3BL

    VK3BL Premium Subscriber QRZ Page

    This Video :)


    PS, a viewer has Kindly let me know MFJ have released an updated version to address these concerns, its part number is MFJ1708B-SDR, and it includes additional relays and a transformer to isolate the receivers from one another! Glad to hear they put the effort in to doing it right in the end, even if I haven't got the chance to test one yet :)
     
  6. VK3BL

    VK3BL Premium Subscriber QRZ Page

    PS, initially the thread was moderated, with no explanation as to why, so I created a nicer titled one, with the same result. It wasn't until I reported my own posts several times that the thread(s) were finally un-moderated, and it took pointing out that I'm re-considering being a premium subscriber to QRZ.com.

    I still haven't received an explanation as to why they were moderated; I have alway been a good citizen on QRZ..
     
  7. WQ2H

    WQ2H QRZ Lifetime Member #214 Life Member Platinum Subscriber QRZ Page

    My dad use to say: "There is no accounting for good taste".

    I agree that a revised title for your video could be more appropriate. But maybe there is something deeply philosophical about saying something 'sucks'.

    I have one that been running non-stop since I got it. I love it. Is it perfect? Probably not. Ces't la vie.

    73
    Jim, WQ2H
     
  8. VK4GAP

    VK4GAP Ham Member QRZ Page

    That was a real painful thing to watch .
    Like just for a example , , why did you not shift 1 trace HORIZONTALLY a bit so one could see it! , i'll leave my other thoughts locked up .

    Paul ...
     
  9. VK3BL

    VK3BL Premium Subscriber QRZ Page

    Honestly? Because I hadn't used that scope in years and couldn't remember how to do it, and didn't think of it before I started recording. We live and learn.

    On the plus side, I found out enough people complained to MFJ about the balance/isolation issue, and they've now released a 'fit for purpose' version - the MFJ1708B-SDR, pay attention to the B ;)

    Quite a few people let me know about their horror stories with the original; one guy blew up his Pixel Loop RX Antenna... not sure how but damn that sucks.
     
  10. VK3BL

    VK3BL Premium Subscriber QRZ Page

    Dear Jim,

    If its connected to two good receivers, there likely isn't an issue. Its the guys who connect them to the 'wrong' SDR Dongle that run into all sorts of problems

    As for sucks... well... the minute I saw the schematic I was peeved and of the impression MFJ were taking the piss out of their customer base... it just took a while for one to come across my desk so I could prove it.

    I'm happy yours is working out for you, however.

    73, Jarrad VK3BL
     

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