Here's another blast from the past, from forty-odd years ago -- Poseidon's first stab at their "upstream diaphragm-actuated servo-assisted system" (which just rolls right off the tongue) -- the "Cyklon Maximum," which would later become various models of the "Jetstream," including "Thor," "Odin;" and, more recently, the "MK3."
The most conspicuous difference from newer models was certainly the lack of a switch on the second stage; and in that sense, more closely resembled the function of the Xstream, of some twenty years later -- while also sharing nearly identical LP valves, and even very similar IP settings (8.8 bar for the Maximum versus the Xstream @ 8.5).
Paired to that was a 2801 balanced first stage, which featured a 200 bar fixed yoke in the US model (a bit unusual for Poseidon) and an optional DIN conversion that would allow for a maximum of 300 bar (4200 psi).
Without going too much into the weeds, it was also among the first of the 2800s to feature a cupped "valve piston" in the balanced housing, in lieu of the old "spring guide," which was later used with the 3700 series, and looked confusingly out of place.
A friend, who had purchased it last Winter, along with a cache of old parts and tools, told me that the seller had mentioned that it had been "recently looked-at" -- though that slightly-worn "membrane with washer," seen below, suggested otherwise.
For those familiar with working on later Jetstream models, the Maximum low pressure valve possessed a few slight differences, including a multi-piece metal valve insert, in lieu of the later plastic one-and-done, whose silicone "sleeve" or "condom" to many, was to be replaced at each servicing, as well as a more heavily-built servo, that had been composed of four parts (including the o-ring), instead of two.
Sadly, that original servo valve had been swapped out for a more modern version, since I had hoped to finally futz with one of those. I had heard that they had been fiddly and easily prone to damage (sharing a thin, delicate edge, similar to that of a Cyklon valve seat).
Here are a bunch of various regulator components, along with a parting photo of the late Ingvar "Ingo" Elfström, the founder of Poseidon, caught in a real Sea Hunt moment, sporting both a Unisuit (they were great -- the first neoprene drysuits) and the Cyklon Maximum from 1981 . . .
The most conspicuous difference from newer models was certainly the lack of a switch on the second stage; and in that sense, more closely resembled the function of the Xstream, of some twenty years later -- while also sharing nearly identical LP valves, and even very similar IP settings (8.8 bar for the Maximum versus the Xstream @ 8.5).
Paired to that was a 2801 balanced first stage, which featured a 200 bar fixed yoke in the US model (a bit unusual for Poseidon) and an optional DIN conversion that would allow for a maximum of 300 bar (4200 psi).
Without going too much into the weeds, it was also among the first of the 2800s to feature a cupped "valve piston" in the balanced housing, in lieu of the old "spring guide," which was later used with the 3700 series, and looked confusingly out of place.
A friend, who had purchased it last Winter, along with a cache of old parts and tools, told me that the seller had mentioned that it had been "recently looked-at" -- though that slightly-worn "membrane with washer," seen below, suggested otherwise.
For those familiar with working on later Jetstream models, the Maximum low pressure valve possessed a few slight differences, including a multi-piece metal valve insert, in lieu of the later plastic one-and-done, whose silicone "sleeve" or "condom" to many, was to be replaced at each servicing, as well as a more heavily-built servo, that had been composed of four parts (including the o-ring), instead of two.
Sadly, that original servo valve had been swapped out for a more modern version, since I had hoped to finally futz with one of those. I had heard that they had been fiddly and easily prone to damage (sharing a thin, delicate edge, similar to that of a Cyklon valve seat).
Here are a bunch of various regulator components, along with a parting photo of the late Ingvar "Ingo" Elfström, the founder of Poseidon, caught in a real Sea Hunt moment, sporting both a Unisuit (they were great -- the first neoprene drysuits) and the Cyklon Maximum from 1981 . . .
