The tests I ran on AM prior to writing the article yielded a very cleanĭisplay on my HP spectrum analyser. Actually, I wrote my article from a purelyĪcademic standpoint my amateur AM career ended rather suddenly at the end That's the kind of company I can support, were I to find myself in the market for a contemporary transceiver (not likely). Flex Radio, the makers of the SDR1000, have taken individual, specific suggestions from users and swiftly implemented corrective action or improvement in response. That's in stark contrast to other manufacturers who have developed DSP radios. I found his point especially interesting that Icom won't deal with such a problem if it considers the number of complaints small. I had asked an expert on the DSP based Icoms to help shed light on the distinctive and unattractive sound the 756 makes when used on AM, and to share the unreceptive level of interest a factory rep responded with when I telephoned Icom about this widespread and audible problem.Īlthough two questions are left unanswered (why this digital dirt can be heard at all amplitudes, and whether there are input sensitivity differences between the 718 and 756), this is one of the more relevant answers to explain what could be causing the noise.
It's possible the 718 is cleaner on transmitted AM than the 756 Pro II and III models because it does a better job handling higher audio input levels. I seem to remember the finals were not cheap. As stated in an earlier post, 25 watts or less, is recommended and encouraged, for most of Icom's rigs that have AM capability.
They did not recommend long key down in the AM mode at 40 watts. Icom technical support stated to me at Dayton two years ago, the 40 watt AM max is for a "very short" duration of time. Although Icom has stated in many of their current rigs 40 watts AM max., some distortion products do/or can appear on the output signal in the AM mode. I can't remember if they use identical final transistors.
In many respects the 718 is a scaled down version of the 706, but with larger cabinet, display, knobs, etc. Any comments on this or I am I missing somthing? With my old tube SSB tranceiver (Tempo One) you could not run more that 25W of carrier, but I believe that was a duty cycle limit. carrier power applies when both sidebands are part of the total power. I think if the finals can handle the duty cycle, this is OK since it is SSB with carrier added. The IC-718 seems to run fine at 40W output power on "AM".
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