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Re: Hints for finding why my RXTX 6.1 is deaf?

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  • pontjakken
    Hi Tony, Thanks! It s alive now but I think sensitivity isn t very good so I will look into the T4 aswell. I m only testing with a few meters of cable as
    Message 1 of 3 , Feb 27, 2007
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      Hi Tony,

      Thanks! It's alive now but I think sensitivity isn't very good
      so I will look into the T4 aswell.

      I'm only testing with a few meters of cable as antenna inside
      but I can only hear 1 or 2 very faint CW signals.

      If the kit is working 100% I should be able to pick up some stronger
      even with a simple antenna? I'm living in a flat at the moment so my
      whole shack is packed in boxes at the moment and have no means of
      putting my bigger antennas up. :)

      73 de Jörgen SM4WWG

      --- In softrock40@yahoogroups.com, "Tony Parks" <raparks@...> wrote:
      > Hi Jörgen,
      > Please check to make sure pins 1 and 7 of U8 are at about 2.5 volts
      DC. Also make sure the QSD circuit is enabled with pins 1 and 15 of
      U7 near zero volts DC. The gate of Q6 needs to be high to connect the
      RX input to the antenna connection on the board as well as having the
      PA LPF components, (L3, etc. ), mounted on the board. The signal
      level on pins 3, 6, 11, and 12 of U7 will be very low unless an RF
      source is used to inject a -20 dBm signal at the antenna input.
      > One common problem is how T4 is connected to the circuit board. If
      leads are not connected properly the RX sensitivity will be reduced by
      40 dB or so.
      > Thanks for getting the information to me on the circuit board
      problem. I will post soon you findings.
      > Thanks and 73,
      > Tony KB9YIG
      > ----- Original Message -----
      > From: pontjakken
      > To: softrock40@yahoogroups.com
      > Sent: Monday, February 26, 2007 8:04 AM
      > Subject: [softrock40] Hints for finding why my RXTX 6.1 is deaf?
      > Hi all,
      > I just finished building the RXTX 6.1 kit.
      > When checking the 800 Ohms between ground and +5V i discovered
      > some shorted pads (I have informed Tony on this)
      > Anyway, after fixing the grounded pads I now tried the kit.
      > It draws about 30 mA in receive mode (the only mode tested so far)
      > but it seems absolutely deaf. No signal on the I Q-output.
      > I've checked the clocks and I have signals on pins 14 and 2 on the
      > FST3253 (S0 and S1).
      > But nothing special on pins 6,3,11,12 (1B1, 1B4, 1B2, 2B3) or pins 7
      > and 9 (1A and 2A). The scope measures anything on those pins (in
      AC mode).
      > Shouldn't there be something to see on the scope on any of the other
      > pins, even without any antenna connected while receiving?
      > Nothing special happening on the op-amps on U8 either.
      > Any ideas on what to check for, do, etc?
      > Best regards // Jörgen SM4WWG
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