There are many ways mixing spurs can appear - several formulas, some specific to the IF frequency of the receiver. Multiples may appear on one frequency, sometimes multiples including a common station.
But also don't limit the thinking to daytimers when the spur disappears at night because it culd be a fulltimer which changes power, pattern or both at sunset generating something only with day facilities, or, if the mixing product ( and this is actually more frequent ) results from a source external to either station, it probably takes a certain amount of field strength at that point to create the spur, hence a reduction in power or a change in pattern could make it disappear. Russ Edmunds Blue Bell, PA ( 360' ASL ) [15 mi NNW of Philadelphia] 40:08:45N; 75:16:04W, Grid FN20id <[email protected]> FM: Yamaha T-80 & Onkyo T-450RDS w/ APS9B @15' AM: Modified Sony ICF 2010 barefoot --- On Mon, 2/23/09, [email protected] <[email protected]> wrote: > From: [email protected] <[email protected]> > Subject: Re: [IRCA] Image Frequency Question > To: "Mailing list for the International Radio Club of America" > <[email protected]> > Date: Monday, February 23, 2009, 8:47 PM > Here in the Detroit Michigan area, we have at least one > intermod: > > FM band: 98.7 + 105.9 = 204.6 / 2 = 102.3 and due to the > capture effect > on FM, only the stronger of the two signals (98.7) is > heard. Both > transmitters are approx. 5 miles apart from each other. > > And as a side note, back to the original request, I'd > look at 730 + 970 = > 1700 / 2 = 850, especially if 73 is a daytimer and if it is > heard on more > than radio. > > Good job, and 73 de Joe, KJ8O, Troy, MI > > > > On Mon, 23 Feb 2009 16:28:16 -0700, Deane McIntyre wrote > > On 23-Feb-09, at 1:46 PM, Ty T wrote: > > > > > Hello, > > > > > > While the topic of frequency imaging is being > discussed, I have one > > > to ask. Here in Billings, MT I can pick-up our > local 970, KBUL on > > > 850 during the day. It comes in just like it was > actually on 850. > > > At night, it is no longer present and KOA Denver > usually comes in > > > like a local themselves. Any ideas why 970 > images onto 850? The > > > other locals here are 730, 790, 910, 970 and > 1240. The only other > > > imaging I have noticed locally is a faint image > of 730 onto 1090. > > > > > > > Most likely a mixing (intermod) product with your > local on 910. > > 2 x 910 - 970 = 850 > > > > 2 x 910 - 730 = 1090, which gives you your other > mixing product > > > > Here in Calgary I get a few of these from our 50 kW > locals on 660, > > 770, 910, 960, 1010, 1060, 1140: > > > > 2 x 660 - 770 = 550 > > > > 2 x 960 - 1060 = 860 > > > > 2 x 1140 - 1060 = 1220 > > > > are the worst > > > > 73, > > > > Deane McIntyre VE6BPO > > Calgary AB > > > > _______________________________________________ > > IRCA mailing list > > [email protected] > > http://montreal.kotalampi.com/mailman/listinfo/irca > > > > Opinions expressed in messages on this mailing list > are those of the > > original contributors and do not necessarily reflect > the opinion of > > the IRCA, its editors, publishing staff, or officers > > > > For more information: http://www.ircaonline.org > > > > To Post a message: [email protected] > > > -- Joe Miller, KJ8O, Troy, MI -- Grid EN82 -- > --- WOW! Homepage (http://www.wowway.com) --- > > _______________________________________________ > IRCA mailing list > [email protected] > http://montreal.kotalampi.com/mailman/listinfo/irca > > Opinions expressed in messages on this mailing list are > those of the original contributors and do not necessarily > reflect the opinion of the IRCA, its editors, publishing > staff, or officers > > For more information: http://www.ircaonline.org > > To Post a message: [email protected] _______________________________________________ IRCA mailing list [email protected] http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: [email protected]
