One of our favorite controls on our Kenwood TS-480SAT HF transceiver is the Intermediate Frequency Shift (IF Shift). With a simple turn of the IF Shift knob it is possible to reduce interference from an adjacent frequency without changing the center frequency. IF Shift is effective at improving signals with voice (SSB), CW, and digital modes. It does not improve AM or FM signals.
The IF shift is also useful to shift the tone of a voice (SSB) contact by cutting or boosting audio frequencies in the high or low end. This little magic trick sometimes makes the difference between copy and no-copy for signals buried in the noise. IF Shift is useful on radios with and without DSP.
Combining IF shift and selecting a specific IF filter center frequency and IF filter bandwidth is amazingly effective with CW and digital modes. If you are unfamiliar with exploiting IF Shift on your rig, do give it a try with noisy signals.
Also try playing around with the various filters and IF Shift on your rig while monitoring the waterfall display on a computer with a program like Ham Radio Deluxe DM780. The waterfall display provides an excellent way to visualize how the received signal is affected by the radio's filters.
With a little trial-and-error and practice you will quickly find that you are able to zero in on weak stations and improve the audio enough to make the contact. We have used this technique countless times with PSK31, CW, and SSB with excellent results. This technique is also useful to shortwave listeners equipped with a receiver offering SSB and IF shift capability.
Good DX and 73,
By Michael Maher (NJ2X)
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© Michael W. Maher and NJ2X.COM, 2011. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Michael W. Maher and NJ2X.COM with appropriate and specific direction to the original content.