On Thu, Jan 14, 2010 at 1:33 PM, Geoffrey Mackenzie-Kennedy <[email protected]> wrote: > On Thursday, January 14, 2010, at 4:53 PM, Guy Olinger K2AV > <[email protected]> wrote: > > >> This is another one of those subjects that seems to have advanced on >> rumor and inuendo. Actually measuring in-band IMD is not as simple as >> it looks. Basically (whether included on a single chassis or not) the >> apparatus must be able to generate a pair of signals which are >> combined in a way that precludes IMD in the test signal to start with. >> Then the frequencies must be set so that A, B, 2A-B, and 2B-A are all >> inside the passband, (inside the roofing filter for the K3 with dsp >> bandwidth set to match) . > > Hi Guy, > > I don't know about the subject being one that has advanced on rumour and > inuendo, certainly not in "non-amateur" circles, but I agree that measuring > in-passband IMD is not as simple as it looks.
Rumor and inuendo so far as an in-band "problem" exists on the K3...not that it does not exist at all on any receiver. I can think of a few receivers listening to a pile up, both CW and SSB, where the best way I can describe the audio was "muddled" or "muddied" or "ground up" or "mixed together", my common world phraseology for what I impute to in-band IMD. I certainly have listened to receivers that did NOT have this effect, among them my own K3, Orion II, Collins S-lines, and my old 75A3. The first SSB contest I did with my K3 I found that I was greatly helped by its clarity in pileups. It was a great improvement over my MP. I am primarily a CW op, and I was in the SSB Sweepstakes to help with the PVRC club score (sum of both modes). I need every bit of help I can get in an SSB contest. >> I for one would like to see some hard lab-grade facts on the existence >> or non-existence of this "problem". I should have added "...on the K3", so the sentence could not be read out of context. > I can send you direct if you would like some data in the form of a Gain > Distribution Analysis for a receiver in use here. This would not be a K3, but different receiver that you own. And as the direct measurement is a real pain, we would be dealing in what amounts to a "logical inference" based on "do-able" tests on the non-K3 receiver you own. I'll respond to you off-reflector for the details. > 73, > Geoff > GM4ESD ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
