Split Frequency Operation; Puresignal; Setting Up Puresignal - Apache Labs ANDROMEDA ANAN-7000DLE MKII User Manual

RX Independent Tuning: the encoder shifts the receiver up or down in frequency from the VFO
setting, leaving the TX unchanged. Pressing the encoder button clears the RIT offset.
TX Independent Tuning: the encoder shifts the transmitter up or down in frequency from the VFO
setting, leaving the RX unchanged. Pressing the encoder button clears the RIT offset.
6.6 Split Frequency Operation
Split frequency operation is enables using the SPLIT button. An indicator on the display is activated
when SPLIT is enabled.
If RX2 is disabled: VFO A will be used for RX, and VFO B will be used for TX
If RX2 is enabled: VFO A provides both. The RX frequency is displayed as normal; the TX
frequency is displayed in the band segment display.
6.7 Puresignal
Puresignal provides an algorithm to correct the non‐linearity. It does that by measuring the
difference between the actual output and the intended output, and correcting the TX samples to
allow for the difference. This algorithm was designed by Warren Pratt NR0V and leads to TX signals
20‐30dB "cleaner" than those with no correction. This all happens in the background, once it has
been initialised.
Puresignal takes a sample of the TX signal after the high power amplifier. ANDROMEDA includes a
suitable signal coupler. If you use an external linear amplifier, then you will need add a suitable
coupler (which could be built into your amplifier).
6.7.1 Setting Up Puresignal
1. Follow the guidance to set up your microphone, drive, antenna and filter selection for
"normal" TX.
2. Select the Menu > Linearity form. The Puresignal Control form will be shown.
3. Click the AmpView button. You will see the AmpView form, ready to show linearity
corrections.
4. Use the Drive encoder to select the power level you want to operate at.
5. Connect a dummy load with appropriate power rating to your antenna connector (ANT1,
unless you have selected a different antenna).
6. Click the left menu button until Setup is displayed. Set Duplex to on.
7. Click The console display zoom 2X button
Click the Two‐tone button on the front panel. You will see your TX signal as two tones in the
panadapter display area. Puresignal will rapidly adapt the signal to reduce intermodulation to much
lower values.
8. After a few seconds the TX display should be stable. Click Two‐tone to off to complete the
calibration test.
9. The AmpView button will have updated to show the amplitude and phase behaviour of the
amplifier, and the correction that has been made.
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