Spectrum DSP M2 User Manual page 61

Recommended procedure for adjusting RX IQ gain and phase adjustments
1. Set the Spectrum DSP to LSB mode.
2. Set the AGC to FAST mode so that the receiver recovers more quickly from the "clicks"
that occur during the phase adjustments.
3. Tune in a strong, constant signal. This could be a shortwave broadcast station or a
signal generator – a signal generator is preferred.
4. Tune the Spectrum DSP dial frequency 1 kHz above the carrier frequency to obtain a
strong 1kHz audio note. Example: If your signal generator is set to 7200 kHz, you
would tune to 7201 kHz.
5. Now tune the dial 2 kHz lower, that is to a frequency 1 kHz below that of the signal
generator: You may hear a 1 kHz tone "leaking" through from the other side.
Following the example, the dial frequency would now read 7199 kHz.
6. If you hear a tone, adjust "LSB RX IQ Bal." to minimize the amount of leakage. Now
adjust "LSB RX IQ Phase" to further minimize the signal leakage. If no obvious
improvement is obtained, set this to the default value (0). In any case, note the two
values obtained.
7. If you have selected the "RX LO LOW" mode of frequency translation, tune the dial 11
kHz higher than the generator's frequency. Following the example, the dial frequency
should now be 7211 kHz. If the "RX LO HIGH" mode of frequency translation is
selected, tune the dial 13 kHz lower than the generator's frequency. Following the
example, the dial frequency would now be 7187 kHz.
8. If you hear the "leakage", adjust "LSB RX IQ Bal." and "LSB RX IQ Phase"
alternatively to minimize it. Once minimized, note the two values obtained.
9. Use the set of values obtained during the adjustment that caused the most difference
when adjusting both the "LSB RX IQ Bal." and "LSB RX IQ Phase" settings, with
preference on the values obtained in step 7.
10. Repeat the steps, above, in USB mode, adjusting the parameter "USB RX IQ Bal." and
"USB RX IQ Phase".
◦ For this procedure the frequency used in Step 5 would modified such that one
would tune 2 kHz above the frequency where a 1 kHz tone would be heard, or 1
kHz above the signal generator frequency. (The dial frequency would be 7201
kHz, using the example above.)
◦ If "RX LO LOW" translate mode is used, the frequency used in Step 7 would be
13 kHz above that of the frequency generator. (7213 kHz, using the example
above.)
◦ If "RX LO HIGH" translate mode is used, the frequency used in Step 7 would be
11 kHz below that of the frequency generator. (7189 kHz, using the example
above.)
11. Repeat the steps, above, in AM and FM modes, adjusting the parameters "AM RX IQ
Bal." and "FM RX IQ Bal.", respectively.
Spectrum DSP M2 User Manual V1.1
– Frequency translate mode ENABLED:
P 61