SP 109 vs (balanced) 250, my experience

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Idea: why not swap parts to make the 109 balanced, and the 250 not? If I still like the 250, then it’s because of case geometry and/or VIVA. If the 109 is better, then I know I like a balanced second stage. I’ll have to look at a schematic...
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This weekend I cleaned my regs, took the best of two 109s to make one good one, and tuned everything using a DIY manometer. 109 has a good (old) lever, duro-poppet w/ fresh seat, and old(er) metal orifice. 250 has a 1yr old s-poppet seat and metal orifice, and bent (non parallel) lever feet. The levers are of the same shape/ design otherwise.

On the bench, the 250 cracks about .8-.9 and is more forgiving. The 109 cracks 1.1-1.2. in and is harder to find the exact cracking point. Both are tuned to 5-min past free-flow.

Underwater (~45 fsw) the 109 is smoother than before (stepped performance gone), and with no other frame of reference is adequate. The 250 still feels more natural, while the 109 actually influences how I breathe (I just learned that this is called “positive inhalation work”.) I actually tried exhaling only through my nose to eliminate the feel of the larger exit orifice on the 250, but yes, the 250 exhales a little easier.

I like the weight (and vibration damping?!) of the 109 and it’s much quieter on inhale. If I stop and just breathe I can feel a slight unevenness to the 250 which I think is the lever feet. Therefore still I prefer the 109 but wish it felt more natural.
 
@buddhasummer : 108Hp (It has the replaceable orifice) :poke:

If I could get new face plates and new rubber diaphragm covers that fit I'd be all over the BAs again but the inability to get these parts turned me to the Conshelf. I've got 10 brand new OEM face plates, numerous new OEM diaphragms and exhaust valves for them. As a consequence I'm happy to dive them and not be concerned at all about scratches, wear and tear etc I sleep easier. I'm mad, crazy not angry.
 
Shirley everyone could send all their faceplates to the one that tinkers in brass
and after some massaging and some panel beating conduct a communal chroming
 
Shirley everyone could send all their faceplates to the one that tinkers in brass
and after some massaging and some panel beating conduct a communal chroming

I got a bunch done a year or so ago but was then stuck with the dilemma, look so pretty don't want to scratch them. Sold the lot. It was too much hassle to repeat.
 
You should test dive a Sea Hornet B Commander second stage... final refinement before they closed down.
They are also very easy to service with standard o-rings and simple cup LP seals...
Adjustable AND were designed to crack reliably at 0.5" (I was dubious but tested on a magnehelic... they really do) with the patented Turbo boost as a bonus...
Try one and really go crazy :D
 
You should test dive a Sea Hornet B Commander second stage... final refinement before they closed down.
They are also very easy to service with standard o-rings and simple cup LP seals...
Adjustable AND were designed to crack reliably at 0.5" with the patented Turbo boost as a bonus...
Try one and really go crazy :D

Photos?
 
Ha ha ha ha yes that's certainly how it is but I just bash them up some to make them match

yeah gathering all the other parts and repairing all the other parts is bit more than I'm willing to invest these days
crushed a faceplate on the boat yesterday I'll just take that off and straighten it so it doesn't impede the diaphragm

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I did the 109 almost 20 years ago, it's never seeing water
the dull reg I also had done then, but dulled it up for effect
 
the dull reg I also had done then, but dulled it up for effect
Yeah I still haven't forgiven you for doing that to a Porpoise :wink:
 
https://www.shearwater.com/products/teric/

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