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Re: [softrock40] Re: 6m Ensemble RXTX

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  • Shirley Márquez Dúlcey
    Like people said, the CMOS switches in the Softrock radios don t work well above 10m. The VHF Softrock receiver uses a preamplifier and mixer in front of the
    Message 1 of 8 , May 13, 2013
      Like people said, the CMOS switches in the Softrock radios don't work well above 10m. The VHF Softrock receiver uses a preamplifier and mixer in front of the QSD; a VHF transmitter could be designed using a similar approach but the Softrock series does not yet include such a design. Other SDR designs that cover VHF or UHF bands use different front ends: either a mixer for downconversion or a high speed DAC for direct sampling at the receive frequency. (Or they just have poor sensitivity like those DVB sticks.)

      The C version of the Si570 has enough range (barely) to cover 6M; for normal sampling you need an oscillator frequency of 4x the operating frequency. (Subharmonic sampling is another possibility; the fixed-frequency Softrock Lite radios use that on the higher bands.) The more expensive A or B versions would cover 6M easily.

      On Sun, May 12, 2013 at 2:51 PM, Adam Jacobs <jacobs.adam@...> wrote:

      This is something like the road that I am planning to go down when I get some time. I have the 6m transverter that mates to the FT-101. The transverter (supposedly) works, but I don't have an FT-101 to supply all of the various tube plate voltages and such. I scored a broken FT-101 and grabbed the powersupply components, the idea is to build a separate supply for this unit and make a standalone 6m transverter for use with my FT-840. However, I'm not convinced of the receive potential of a tube transverter. Maybe I'm wrong, we'll see. :) So I was planning to build out a 6m Ensemble VHF RX for the receive path.

      -73 Adam W7QI

      On Sun, May 12, 2013 at 8:27 AM, Zack Widup <w9sz.zack@...> wrote:

      The VHF Ensemble II works quite well on 144 MHz as a receiver. I think
      I mentioned here before that it compares with my Yaesu FT290RII which
      needs a little assistance for weak-signal work. An LNA preamp does
      great. I use mine mainly as a microwave IF on receive so I only have
      to watch the display while peaking a signal with the dish, not have to
      try to move the dish with one hand and tune a receiver knob with the

      I suppose for a transceiver you could use the RXTX with an additional
      6m transverter.

      73, Zack W9SZ

      On 5/12/13, Alan <alan4alan@...> wrote:
      > ----- Original Message -----
      > Subject: [softrock40] Re: 6m Ensemble RXTX
      >> Well I got an email that the si570 and multiplexers in the kits won't do
      >> much above 10meter. So it looks like I'll need to do
      >> some research and see if there are pin compatible replacements that will
      >> handle the frequency range.
      > David,
      > No, the Softrock Ensemble does not seem a good choice for 6m. You can use
      > subharmonic mixing but sensitivity is poor. A preamp would
      > help.
      > But there is a VHF Ensemble with a mixer. That may be built for 6m and
      > performs well.
      > As Alan says, the UHFSDR can be built to go much higher. I'm not sure that
      > is quite as straightforward as a Softrock? I'll have to
      > try one some day.
      > 73 Alan G4ZFQ
      >> --- In softrock40@yahoogroups.com, "kb9gpm" <goofy_36@...> wrote:
      >>> I'm curious about something. Has anyone tried to build an Ensemble RXTX
      >>> to work on 6 meters. It seems like it would be a matter
      >>> of changing the receive and transmit filters. I'm also assuming the
      >>> si570 in the kit will run up that high.

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