► As been reminded in a prior reply, the early F5's used push-on connectors and then they went to screw-on connectors. Get an F5 that uses the screw-on coil connector.
► I considered an F5 but was encouraged to buy and Omega 8000 in March of 2010 and it quickly became my preferred urban Coin Hunting model. I bought the pro package and compared coils at many sites for a couple of weeks. I preferred the 'standard' elliptical Concentric to the 11" BiAxial (DD) coil, and in typical urban trash I liked the 5" DD. Then I borrowed the round 8" off a Delta I bought for kids to use and preferred that for typical day-to-day coverage. My Omega-preferred coils were the 8" Concentric and 5" DD. That combination worked very well for me.
► Because I spend the bulk of my detecting time working ghost towns and other sites that have very dense concentrations of nails and other ferrous debris, I use more dedicated models that provide me with superior handling for dealing with iron nails being barely rejected and providing a quicker recovery speed to produce a fast response on nearby desired trash. The F5, Omega, and many detectors struggle in that regard, and in the late summer of '15 I sold/traded my Omega, as I had my T2 w/5" which was, at the time, my better Relic Hunting device before I switched to a superior make/model. I had moved to a dinky town of 535± people and had very little Coin Hunting opportunities like I used to.
► Fall of last year, I decide that due to health and mobility concerns I just can't get to as many out-of-the-way older sites and will have to spend more time working urban parks, schools, parking strips, etc., etc. So I added an Omega 8000 back into my arsenal, and spotted an ad for a 7" Concentric coil, the same one used on the Fisher F11. Got it, mounted it, and have totally enjoyed using the 7" Concentric coil on the Omega 8000, the simplified cousin of the F5. Shortly after, I bought another Omega 8000, a V.6, that came with three coils including a 7" Concentric which I keep mounted full-time.
► I then bought a Fisher F44 and moved the 7" Concentric from the first Omega 8K to the F44, then mounted the 5" DD on that first Omega 8K, a V.4
► I have used the other coils designed for the F5/F44/Omega 8000 and 8500, as well as the solid 5X10 F19 coil on these models, and while I do keep extra coils on lower rods in my Accessory Coil Tote, I have found the 7" Concentric and 5" DD to be the two best search coils to complement each other for a wide-range of detecting applications.
Just my experiences.
Monte
