"I was wondering if anyone out there still uses a coinmaster 5500D?"... There might be a few (very few) still using the 5500/D on what you might call a regular basis, but few who are really keeping up with modern-day detectors and detecting.
"If so , can anyone educate me on this unit,..."... The 5500/D was introduced in 1985, at the same time the 6000 Di Pro was introduced.
In 1984 White's offered the Coinmaster 5000/D Series 3 for a suggested retail of $399.95. It was a 4-mode unit with a signal intensity/battery check meter and used the drop-in 4-AA battery holder.
In 1985, it was 'replaced', so to speak, by the 5500/D Series 3 which also retailed for $399.95 AND now offered the rechargeable battery system and Coin Depth reading of the former 6000/D Series 3 (from '84). In short, they dropped the 5000/S Series 3 and basically renamed the 6000/D Series 3 as the 5500/D Series three to reduce the number of '6000' labeled models in their line-up since they had the 6000/Di and 6000/D in 1984, and were just introducing the 6000/Di Pro.
I think the required sweep speed of the 5500/D & former 6000/D was just a touch slower than that of the 5000/D models i the GEB Disc. mode.
"... like what the difference is between the 6000D and what the i in Di models mean."... The 6000/D, like the 5000/D and 5500/D was a "motion discriminator" in the GEB Disc. mode, and that's what the 'D' stood for. Discriminator.
The 'i' in 'Di' stands for "identification" noting that those models featured the VDI display meter. (Visual Discrimination Identification).
The 6000/D offered "coin Depth" reading, as did the 5500/D which replaced it, and the 6000/Di offered both Coin Depth reading as well as VDI (commonly referred to as TID or Target ID).
In 1986 they retained the '6000' label for the 6000/Di Pro which was released in April of 1985, but went to the new model name of 5900/Di to replace the 6000/Di which they had dropped briefly. The goal was to reduce the confusion between so many models with '6000' in their name.
The term "Pro" used in 1985 for the top-end 6000/Di Pro was used to indicate that it featured White's new Autotrac
