109 Second Stage on MK10 or MK5?

[herman]

Vintage ? No, reguardless of what the board might say, 75 is more the accepted date not 80.

In any case, assuming the first stages are both set at the same IP and both are working properly, there is no way you can tell the difference between them when connected to the same second stage. As long as the same IP and flow is in the hose, the second stage does not "care" what brand, make or model of first stage is supplying it. While there may be some first stage differences at full flow, no one can breath a first stage that hard so that does not matter in the real world. Bottom line is, go with what you like, the first stage will not make any difference.

 

[Couv]

I think "vintage" around here is an indicator of the poster's age. I was working in a SP shop when the G250 came out, it was in the mid 80ies. Zung must have been a pup then.

 

[Zung]

Bro, you're absolutely right: I started diving in '88; before that, I was... pre-sentient!

 

[halocline]

Practically speaking there'd be no difference between the MK10 and MK5 for using your 109, but theoretically there might actually be a bit of a difference towards the end of a dive. I've found that my MK10s have a slightly greater IP drop over the tank range than my MK5s, which I can only attribute to the smaller piston diameter allowing for a relatively greater friction co-efficient at the HP o-ring. I think you can mitigate this by using polyurethane duro 90 (or maybe any duro 90) o-ring and making sure any glaze on the piston shaft is removed with micromesh.

So, with the unbalanced 109, you might find just a bit more of an increase in inhalation resistance at the end of the dive with a MK10 than with a MK5. Probably not.....

I have 8 or 9 109s (most converted) and one G250 (that I loaned out for almost a year and didn't miss) so guess which reg I like better!

BTW, I'd like to find a MK10+ conversion kit, so if anyone has one or two, I'll buy or better yet trade something for it.