I found a speed sign next to my house on K band, and can easily pick it up 0.5 miles over a hill in a 25mph zone -- almost a minute and definitely out of field-of-vision till the last 15 seconds. That was impressive. Range is pretty similar (a bit more) than 1793SE and A LOT longer than my Cobra which could only pick it up from about 30 seconds away.
I found another sign on Ka band (whoa! Ka-band speed sign?) that's mounted high, antenna directed down. Apparently the utility/city workers must have been slacking off, because there's this thick leafy branch right over the antenna from a nearby tree! There's also a road hump about 0.1 miles away from the sign, placing the sign well out of line-of-sight. XTR-690 issues Ka-band alert at about 0.2 miles away, about a block before the hill. 1793SE issues alert once I reach over the hill. Cobra XRS-9300 failed to alert on first pass, and issued a Ka band 1/5 alert when I parked right under the sign and pointed the horn at the antenna.
So, what have I learned today? Well first off the importance of terrain. Secondly, K-band performance is pretty similar on 1793SE and XTR-690, with XTR-690 a bit better though both are MORE than plenty. The XTR-690 is a huge improvement on Ka band, an area that the 1793SE is not terribly strong at. If you live in a Ka band area, there should be no doubt what Whistler platform to choose. Finally, Cobras cannot be counted on for Ka-band detection.
In both cases, ramp-up was EXCELLENT and smooth.
For fun, I also made a few other passes:
(1) 1793SE POP ON vs OFF: No difference observed on K-band that couldn't be explained as just natural variance. Ka band gains a bit of sensitivity, though not enough to make or break a save.
(2) FILTER: As one'd expect, FILTER has no effect on detection distance.
(3) XTR-690 K-band OFF: At about 1/4 the original detection distance on the first sign, I got an X-band alert.
(4) High vs Low mount: High mount increased range slightly, and in the case of the over-the-hill Ka on 1793SE, it made a very notable improvement. got alert at bottom of hill on high mount vs at the midpoint.