Casual operating comments in the review text for the most part failed to identify this particular anomaly, even though it very likely degraded the results of some intermodulation distortion tests. This brief paper describes both a source and correction for what we now identify as “The Noise Blanker Drive-Signal Leakage Problem.”Įarly reviews by RSGB and DLARA, and ARRL remained within their structured testing schemes, for consistency. Now that we know their source, it makes perfect sense that their reported characteristics varied, and that some folks didn’t hear them at all. These signal artifacts were variously described as ‘phantom signals’ or ‘ghosts’ or ‘rumble’, and were so variously reported, as to be completely rejected by ICOM. These signals took on a lot of characteristics, and weren’t observed by all amateurs. Shortly after Icom’s IC-756 Pro HF/6 meter transceiver was introduced into the US, one of the authors observed that signals within the upper IF bandwidth could be heard, even though they were well outside the lower IF filters. You may not rewrite or reproduce it, in any way, nor may you remove the copyright paragraph.
You may give copies to other amateurs, in printed or soft form. You may provide links to sites where this piece is found. This short version is provided for web posting through specific web sites, previously authorized. This condensation may not be distributed or republished, without express permission of the authors, or of ARRL. Correcting the IC-756Pro Noise Blanker Drive-Signal Leakage ProblemĬorrecting the IC756Pro Noise Blanker Drive-Signal Leakage Problem by Jim Jarvis N2EA and Tony Brock-Fisher K1KPĬOPYRIGHT: This piece is a condensed version of Technical Correspondence, QST, June 2002, p.68.
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