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Re: transmit images with Rocky

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  • tj_alberta
    Thanks Tony, I am using the J2 out jack on the break out box to feed I/Q into the transmitter. I checked the cable and connections with an ohm-meter and the I
    Message 1 of 4 , Dec 2, 2007
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      Thanks Tony,

      I am using the J2 out jack on the break out box to feed I/Q into the
      transmitter. I checked the cable and connections with an ohm-meter
      and the I & Q inputs are not shorted together and all the cable jacks
      and sockets are in good order.

      I monitored the input on the R & L pads on the board with my Delta 44
      set to -10 dB and with the 20m CW xtal selected, and found the output
      power with one tone (Rocky transmit test) 0.65 watts.

      With these settings I measure about 2.0 V P-P on C3 and C10. I
      checked singal level by placing the scope probe on the top of R3 or R9
      R6,R12, R8, & R14 are found all to be at just above 2 V P-P. The
      same voltage appears on R5 and R11.

      With the two tone test, power out went down to 0.275 watts

      If I change the sound card settings to + 4 DB the one tone test gives
      1.5 Watts out. If, on the Rocky transmit tab settings I reduce the
      gain until the power out reads just under 1 Watt there are still
      images. I think + 4dB is too high with the Delta 44 as I measure >7
      v P-P.

      On either sound card setting (-10 dB or +4 dB there are images).

      There is probably some really simple explanation for all this -- but I
      have not been able to find it. Further suggestions will be most
      welcome.

      73

      Earl, 4Z4TJ

      --- In softrock40@yahoogroups.com, "Tony Parks" <raparks@...> wrote:
      >
      > Hi Earl,
      >
      > Please check the TX I/O output setting. Make sure the TX output is
      no more than one watt.
      >
      > 73,
      > Tony KB9YIG
      > ----- Original Message -----
      > From: tj_alberta
      > To: softrock40@yahoogroups.com
      > Sent: Friday, November 30, 2007 9:22 AM
      > Subject: [softrock40] transmit images with Rocky
      >
      >
      > 1) All of a sudden I am getting transmit images with rocky. Both in
      > CW and BPSK. For example, if I am 10KHz above the center freq then
      > there is an image every 10 KHz above and below center freq; if I am 15
      > KHz from the centre freq the images are +/- 15 KHz. These images are
      > real - I can hear them on a separate receiver. Sound card settings
      > look alright. Help? I have worked over 15 countries on QRPp BPSK
      > this week and would like to fix the bug asap.
      >
      > 2) With Power SDR I am only transmitting a CW signal on the center
      > freq. and it is very weak - can't find a way to increase power out. I
      > am getting full power out with Rocky. I remember I had this problem
      > last year with the 40m RXTX but cannot remember the solution.
      >
      > Thanks in advance for your suggestions.
      >
      > Earl 4Z4TJ
      >
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