I'm not usually at a loss for words (as those who know me will quickly attest!) but I am blown away with my experience using my Flex6700 in the ARRL Phone Sweepstakes this past weekend.
I was cooking along - rate was great, I was well ahead of my previous best performance in the contest when PG&E (Pacific Gas & Electric - our local power utility company) struck... the noise floor on 10m jumped to about S4 with the familiar growl of power line noise. Not a surprise... we're just into the start of our "wet season" here in Northern California and arcing/leaking insulators are an annual pre-Thanksgiving visitor at my QTH.
The noise was strong enough to make copying many of the weaker callers much harder. A real rate killer at 1pm on a Sunday afternoon in Sweepstakes.
SOP (Standard Operating Practice) - change bands - down to 15m I went. Oh... bother! Same noise, about the same signal strength... No, I am not going to fight for a run frequency on 20m or put up with the lower rate of S&P on that band.
Wait a minute! A couple of weeks ago I finally installed the Inlogis PixelLoop that I had purchased at Visalia and which had kept my car company in the garage ever since... I had purchased the PixelLoop as a receive antenna for the low bands - primarily to help on 160m. The PixelLoop is good at rejecting local noise sources... wonder how it works on 10m?
A quick selection of the RX-B antenna port for the receive antenna and bingo! Not bad considering I haven't finished the remote control rotor system to change the (currently fixed 70 degree) azimuth of the loop.
Wait another minute! What if I run the SteppIR DB18E (the transmit antenna of course) and the PixelLoop in diversity mode on the 6700? Hmmm.... past experiences with the Flex5000RX2 in diversity were pretty mixed and I'd eventually passed on that experiment even though it was one of the reasons I'd purchased the second RX in the 5000. All my reading on diversity had suggested that two similar antennas were needed with physical separation... can't get much more "dis-similar" than a loop and a yagi!
[ADDED CLARIFICATION] Several folks asked my about the Flex5000 results I mentioned above... to be clear, when I did those first experiments with my 5000RX2 it was with two closely spaced and medicore antennas. The two receivers in the 5000 are phase synchronous - just like the two SCUs in the 6700 - with well separated and similar antennas I would expect similar results from the 5000RX2 as I get on the 6700. [\ADDED CLARIFICATION]
I punched up diversity mode, set the second slice to use the RX-B input (and therefore the second SCU in the 6700) with the primary slice using ANT1 and the DB18E.
Like many people, I have "bucket" hearing loss in one ear - in my case, likely environmental exposure to too many shotgun blasts when I shot skeet competitively (20K targets in a typical year)... so the default configuration in DIV mode putting one slice full on the left channel and the other full on the right didn't feel quite right especially with the gain differences between the two antennas... The adjustment didn't take long - equal left/right allocation for the primary antenna, loop full on the right and a slight audio level adjustment to compensate for the bucket hearing in my right ear.
OMG! Wow! Wicked! (and my pet peeve despite my British origin) Brilliant!
I had just discovered a way of plugging my brain into two antennas. Direct high speed bus connection to a neural processor with millions of years of development! The K6TU WetWare Neural Processor was now directly bus connected to the radio.
In my installation, there is about 600 feet separation between the loop and the DB18E on my tower. I'm lucky (very lucky!) to have the space and also the distance it provides from my neighbors (most of whom I like ;-) to space out the antennas.
On 10m, this equates to around 20 wavelengths while on 160m, I have about 4 wavelengths between the vertical and the loop. This gives good spatial separation between the two antennas which helps with selective fading, shifting paths in the ionosphere and different angles of arrival from geographically separated stations.
Its really hard to describe the result and in the heat of the contest, I wasn't about to reach for the audio recorder to grab samples.
Our brain has an amazing audio processor as part of its configuration - some folks are really good at not turning it on (they are the one's who don't listen very well)... but the rest of us have a lifetime of experience in leveraging its controls.
Single signal experience
Strong or weak, using the two antennas in diversity mode sounded like the station was bouncing around inside my head! When one channel would fade, the other would typically get stronger with the sensation that the station was walking around in front of me. It made it much (and I mean MUCH) easier to pull out the weaker stations especially with the power line noise issue.
Pile up experience
This was freaky! In a typical pile up with multiple callers, often the best technique is to get a fragment of a call and focus - "Whiskey Nine - again?" - instead, it was like the calling stations were all around the room - spread out spatially inside my head. Rather than pulling out a fragment of a callsign, I'd find I could clearly hear a full callsign and go right back to one of the callers.
Maximizing score in a contest is about time management... writing my post on the 2014 Sweepstakes yesterday showed this in spades. Taking breaks, efficiency in sending and receiveing the contest exchange all contribute minutes per break or seconds per contact. In the course of 24 hours and 1000+ Q's, seconds turn into HOURS. My average rate in the Phone Sweepstakes was around 65 Q's/hour - my best hour was over 100 Q's... gaining another couple of effective HOURS translates in several hundred more Q's.
I ran the entire rest of the contest in diversity mode - my rate was significantly improved, my motivation was higher and the fun factor was off the charts.
I think this is my new closing tag line...
If you aren't using a Flex 6000 6700 radio, you aren't using the best tool for the job.