On 03/25/21 12:50, Edson W. R. Pereira wrote:
>
> I have an old IC-821 that recently started having CPU issues and am not
> sure I will be able to fix it. I am in the process of rewiring the dual
> PA and front-ends to my PlutoSDR.
>
> With the present availability of SDRs like PlutoSDR, LimeSDR, BladeSDR,
> etc., it is much easier to use them to receive (and generate) signals,
> but they lack good filtering and adequate RF power. It would be nice if
> we could have some commercial solutions.
>
> 73, Edson PY2SDR
Hello Edson,
It seems that an outboard filtering "box", with the appropriate
band-select signals from the SDR, would be a good solution.
Indeed. I have rescued some BPF from old equipment and have been using them for RX for some time. Now I am trying to get TX.
It could incorporate RF amplifiers, too, to get the signal up to at
least 5W. At that point, a conventional external PA could bring the
signal level up to 100W or whatever the user chooses.
I still have to determine the power level needed to excite the IC-821 PAs. It may be necessary to add an RF buffer.
While I like the ADALM-PLUTO, I don't like the USB interface. USB is
finicky even under ideal circumstances. I would much prefer a GigE
interface into the Zynq inside that box. It could then be placed
anywhere on the network, ideally with PoE so that a separate power
supply would not be required.
You are absolutely right. USB also tends to generate a lot of RFI on HF. I intend to put the pluto inside the IC-821 cabinet with a USB to Ethernet converter plus a media converter to transport Ethernet via fiber. This way I can galvanically isolate the PC from the SDR and antenna and also mitigate some RFI issues. But I am not sure how stable the USB/Ethernet will be.
It would be really nice to have a low-cost SDR transceiver like the Pluto or Lime with a native SFP port.
The design is open-source, so it could be done.
True. Anyone would be interested in a community front-end and PA project for SDR interfaces?
73,
Edson, PY2SDR