Re: K3 ANT to IF OUT Conversion Gain

Wes Stewart

I would call that a second receiver, not a panadapter/bandscope.  I use an SDR-IQ with SpectraVue software for my bandscope.

SpectraVue knows all about the K3/K3S i-f output frequencies v. mode and BW so it displays the tuned frequency in the middle of the screen regardless of those adjustments (if desired, which I do).  It offers point-n-click or mouse wheel tuning.  There is no display smearing, refresh is instantaneous.  No fuss, no muss.

Wes  N7WS

On Monday, October 12, 2020, 5:34:48 PM MST, Bob Wilson, N6TV <n6tv@...> wrote:

On Mon, Oct 12, 2020 at 4:11 PM Robert <rdiamant36@...> wrote:
I am waiting for a used K3 to arrive soon and I am already thinking about using my Perseus SDR as a no cost "panadapter" connected at the IF OUT connector for many years.

I've been using a Perseus SDR as a transceiver panadapter for about 12 years now.  I highly recommend ignoring K3 IF OUT; use K3 RX ANT OUT instead.  This works with many radios, not just the K3.

See my presentation linked from my QRZ.COM page, or the direct link below:
The technique is the same for an SO1R station:  just split RX ANT OUT to (1) RX ANT IN and (2) Perseus ANT IN using a 50 ohm "Magic T" splitter (or a 75 ohm TV splitter).  A BNC "T" connector is not recommended since it doesn't isolate the two outputs.

There are many advantages to doing it this way:
  • No significant loss of sensitivity (just 3 dB from splitter)
  • The panadapter span is not limited by the bandwidth of K3 IF (200 kHz?); you can monitor the entire band with the Perseus, not just a small portion
  • The waterfall doesn't "smear" or move around when you move the VFO knob on the radio.  Frequency sync is no problem.
  • Using a program like HDSDR with OmniRig enabled, you can make the cursor on the panadapter track the VFO of the K3
  • You can use mouse click and mouse wheel scroll on the HDSDR waterfall to move the K3 VFO (something not supported by a P3, but supported by the K4)
  • The "Z" command (auto-zero beat) in HDSDR zero beats CW signals much faster and more accurately than the AUTO SPOT feature, and it can move your K3 VFO to do the same as long as both are calibrated the same
Note:  you must activate RX ANT on the K3, on every band, otherwise the Perseus receives no signal on that band.

Bob, N6TV

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