Are there SDRs on 2m/70cm?

Discussion in 'Software Defined Radio (SDR)' started by K3RW, Aug 8, 2019.

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  1. W6RZ

    W6RZ Premium Subscriber QRZ Page

    Here are two block diagrams showing digital direct conversion and direct sampling. There are advantages and disadvantages to both, but you end up with the same thing. IQ samples at baseband.

    [​IMG]

    [​IMG]
     
    EA1DDO likes this.
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I use two tin cans with a string.

    Absolutely direct conversion (vibration on one end carries along the string to create vibration on the other end), but no code involved.

    Worked when I was 7 years old to talk to my neighbor who was a good 200 feet away. That took a lot of string, and it works best when pulled tightly. ZERO QRM or RFI, a big plus.
     
    EA4BPN and N3AWS like this.
  3. N3AWS

    N3AWS Ham Member QRZ Page

    How did it do in rain, snow, hail, hurricanes, etc.?

    Oh, and in my FL properties we have covenants against strings over 20 ft.

    73
     
  4. W5SAT

    W5SAT Ham Member QRZ Page

    To be honest I really don't know what the point of the discussion is anymore. The OP asked about 2m/70cm SDRs, I weighed in on the IC-9700. Somebody said that the cheap China HT are actually SDRs if you think about it, I said I didn't think that was the case and it's irrelevant anyway because their performance really sucks and now W6RZ is spending all day trying to show me how much smarter than me he is and illustrating his point with a bunch of unrelated block diagrams.

    I'm out.
     
  5. W6RZ

    W6RZ Premium Subscriber QRZ Page

    Sorry, I thought you wanted to learn something about SDR. I guess I was mistaken. :(
     
  6. K3RW

    K3RW Ham Member QRZ Page

    I would just like a 2m or 432 SDR so that I'm not chaining transverters to transverters in order to get on microwave bands.

    I can run 28 MHz SDRs all day, theres no shortage of those. But when I start delving into transverters well above 3GHz I start needing 144/422 or high IFs when I get up to 24GHz and above.

    Perhaps theres really nothing wrong with chaining 2 together. But if I could run a true SDR or 432 I figured I have better performance on 10G+ than not. Partly the ability to PLL and add GPSDO into circuits may be part of that. Running a gunnplexer gets me on 10G easily... but nope. Need a lot more accuracy than that. Can't spend half a contest trying to work 1 station.
     
  7. W5SAT

    W5SAT Ham Member QRZ Page

    K3RW, as far as I know there is only one radio on the market that is a true SDR on 2m and 70cm - the IC-9700. It is a RF direct sampling receiver on those 2 bands. It can be locked to a GPSDO. There are no IF stages involved for 2m and 70cm but there is down-conversion required on 1296 MHz.

    Perhaps I am missing something but it seems this fits the bill.
     
  8. VE7BPB

    VE7BPB Ham Member QRZ Page

    I'm surprised no one has mentioned the PlutoSDR or the LimeSDR.

    My Pluto goes from 70mhz to 6ghz continuously, on both rx and tx, in full duplex. Granted the output power is only 5mw but there are lots of amplifier blocks out there for cheap. Takes a modest PC and you can use free software like SDRconsole to operate it. Or if you want to go even cheaper use a Raspberry PI and the free software available for Linux. I've listened to more than one user on the QO-100 satellite using a Pluto with a 10ghz LNB down-converted on rx and the Pluto direct on the 2.4 ghz uplink with appropriate amplifiers.

    The LimeSDR is also a contender with similar specs except it only goes up to 3.6 ghz, I believe.

    As far as GPS-DO , the Pluto can be used by just soldering one capacitor on the board and connecting the GPS-DO. I have not done this with mine yet, but only because I find it sufficiently stable for my current use.

    And the best part, Pluto is under $200, Lime is around $200, software and information is easily available for both and operation couldn't be simpler.

    regards, Roy
     
    N3AWS, K3RW and EA1DDO like this.
  9. K3RW

    K3RW Ham Member QRZ Page

    It does fit the bill. But even at its current discount its still a hefty chunk, with a bunch of that probably because it has 1.2 GHz. For me I'd rather have a 2m or 432 SDR and run a transverter on that, since I would be running bands other than just 1296 with it.

    I did find there are some 2m SDRs after all. The SunSDR2-PRO being one of them.
     
  10. N3AWS

    N3AWS Ham Member QRZ Page

    Both of these products look exciting! I had never heard of either of them before. Thank you for sharing!
     

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