Scubapro R109

[dave22387]

I believe that they were originally sold as the 'high performance adjustable 2nd stage' with the MK5 1st stage, and the entire set was simply called the MK5. The part number for the 2nd stage was 109. "156" refers to the balanced version of the same 2nd stage.

SP had a popular unbalanced plastic 2nd called the R190, hence the confusion.

Maybe the most successful 2nd stage design in history, in terms of longevity, influence on later 2nd stages, and performance.

Thank you!!!

 

[agilis]

I should also point out as a P.S. that the 109/Mk 5 or Mk 10 DIN regulator combinations that I use, together with another less finely tuned 109 as safety second are used on HP steel tanks, usually filled to the limit for these tanks, around 3700+ hot. My old all brass Mk 5 DIN connector is listed at 3300 lbs. max, but it has handled the slight extra pressure just fine for many years.

I disassemble, clean and inspect my 109 and 156 regulators after almost every dive day, and after every overseas dive trip, not because it's always necessary but because I enjoy doing it and keeping them in nearly new condition however old they may be.

 

[dave22387]

Now I want some !!!

 

[Couv]

I believe that they were originally sold as the 'high performance adjustable 2nd stage' with the MK5 1st stage, and the entire set was simply called the MK5. The part number for the 2nd stage was 109. "156" refers to the balanced version of the same 2nd stage.

SP had a popular unbalanced plastic 2nd called the R190, hence the confusion.

Maybe the most successful 2nd stage design in history, in terms of longevity, influence on later 2nd stages, and performance.

Master Luis provided this in another thread:

The 109 is just the Catalog Number (Part Number) of the second stage that was included as part of the regulators with the Mk-1, Mk-5, Mk-6, and Mk-7 designation.

The Mk-2 and Mk-3 regulators included the 108 second stage.

The catalog numbers for the first stages are as follow:
Mk-1: 101-1
Mk-2: 102-1
Mk-3: 103-1
Mk-5: 105-1
Mk-6: 106-1
Mk-7: 107-1

I don’t recall that there was ever a Mk-4.

The 108 and 109 part numbers were for the second stages. The next second stage that was introduced (in 1976) was the 128 (a.k.a. the Pilot).

A regulator included a first and a second stage. The only reason to buy first or second stage (by itself) was as a replacement part (octopus were not commonly used).


Therefore, the correct (original) label for first stage of a MK-5 is therefore a 105-1, but Scubapro changed their numbering / labeling system when they started mixing first and second stages.


The numbering system that Scubapro used in the 60’s and 70’s was very simple. They never envisioned having as many regulators as they have had in the last 20 years.

The individual parts started with 101-x; where “x” would run from 2 and up.

The 105-1 (Mk-5 first stage) used most of the same parts as the 101-1 (Mk-1 first stage) so most of the parts were 101-x. Only the unique parts would start with a new series of numbers. The swivel was 105-8, the cap was 105-3, etc.


Below are some examples of the 1976 Scubapro diagrams.

 

[Rich Keller]

I use two 109s and two 108HPs alone with MK3s and MK5s.

 

[Slater]

What is a functional SP Mk5 first stage paired with a 109 second stage worth???
Ive aquired two of them, not rigged with octos...
Have no idea how old they are or if the second has been upgraded with 156 parts, decent shape externally.
Looking at the face of the second you can see bright blue silicone purge diaphram.

Have read DA Aquamasters post on these but was curious of value & is there really a large demand for these regs still?
I dive an Aqualung Legend LX so im ok for my personal reg but was hoping for some insight..
Keep them, have the gone through & sell them?Looks like some really still enjoy them looking at past posts, but do they really breath just as good as todays regs at depth?

 

[LeadTurn_SD]

What is a functional SP Mk5 first stage paired with a 109 second stage worth???
Ive aquired two of them, not rigged with octos...
Have no idea how old they are or if the second has been upgraded with 156 parts, decent shape externally.
Looking at the face of the second you can see bright blue silicone purge diaphram.

Have read DA Aquamasters post on these but was curious of value & is there really a large demand for these regs still?
I dive an Aqualung Legend LX so im ok for my personal reg but was hoping for some insight..
Keep them, have the gone through & sell them?
Looks like some really still enjoy them looking at past posts, but do they really breath just as good as todays regs at depth?

The prices for -109's and Mk5's on ebay fluctuate, and it seems like their popularity here on scubaboard has driven up the price in recent years.

I blame that on the "usual suspects" being so darned honest and helpful, and letting the unwashed masses (like me!) know how wonderful these regs are.

I got a great deal: I believe I paid about $35 for my first -109 (unbalanced when I got it) in near-new condition; then soon after I paid about $45 for a late model Mk5 with -109, also in near perfect condition. Both were purchased on ebay, and I think just were not seen by other bidders.

So I ended up with a Mk5 and a pair of -109s for about $80, then chased down parts to rebuild/upgrade the regs myself.... I guess I ended up at around $130 total for regs and parts??

So, if you have someone else doing the rebuild.... you may not make a huge profit, but probably would come out ahead... but really I would just Keep Them!

Breathing: So much depends on tuning the 2nd stages, but for my -109s I've found them to breath very smoothly, with just as low a cracking effort as any of my "modern" 2nd stages, but maybe just a hair less "venturi" effect...

So, subjectively, I have some modern 2nd stages that breath just ever-so-slightly better than my -109's, but this is slight, and I have my modern 2nd's tuned pretty aggressively.... And in my case I suspect when I replace the demand lever on my main -109 with a G250 lever it may breath a hair better still....

Anyway, I did not mean to be so wordy, but yes, the -109's will hold their own with any current 2nd stage, and if they are properly tuned your should only feel the slightest difference between them and current top-end 2nd stages, barely noticeable. I would not hesitate to take them silly-deep.

Best wishes.

 

[Couv]

What is a functional SP Mk5 first stage paired with a 109 second stage worth???
Ive aquired two of them, not rigged with octos...
Have no idea how old they are or if the second has been upgraded with 156 parts, decent shape externally.
Looking at the face of the second you can see bright blue silicone purge diaphram.

It is difficult to say how much they would sell for, but most likely having them serviced will not increase the sale value enough to justify the expense unless you do it yourself. The real value would be realized if you needed a set of regulators. Having them serviced so you could dive them would certainly be worthwhile.....yes, they will perform as well or better than most of the plastic/fantastic POS available today.

If you decide to keep them, contact rsingler here on SB to have them serviced or join us in the DIY forum.

 

[halocline]

What is a functional SP Mk5 first stage paired with a 109 second stage worth???.....
Looks like some really still enjoy them looking at past posts, but do they really breath just as good as todays regs at depth?

View attachment 165820View attachment 165819

Of the two that you have pictured, the 109 is probably worth a little more, because the MK5 in your photo looks to have the 'middle' size yoke, not the heavier later yoke, and it might have a 3/8 rather than 7/16 HP port. It looks like someone has replaced the adjusting knob on your 109, which leads me to believe that it probably has a balanced poppet; just a wild guess. Anyhow, they're worth whatever someone will pay. Maybe $40-50 per stage at the most, but I don't really know.

They breathe quite a bit better than many of 'today's' regulators, but 'better' is a bit of a subjective term. As LeadTurn mentioned, they lack some of the venturi-assist punch that some smaller plastic 2nd stages have. I find that to be 'better', I don't really need a regulator to shove air down my throat. Depth doesn't really have anything to do with how 2nd stages breathe except in extreme cases that recreational divers will never experience. The Mk5 has excellent IP recovery and high flow capability much like your aqualung legend 1st stage; you'd never be able to tell the difference in a blind dive test.

 

[rsingler]

For those following this thread, please know that I currently have about a dozen 109/156 regs that I have gradually acquired on EBay, which I am in the process of restoring.
This will probably be a four-month project, but I have an excellent Chrome shop lined up in Sacramento to help. If after a test run, I'm happy with their work, then the plan is to bead blast, rechrome and polish the cases. I will rebuild as either late 109s (duro poppet) or 156 (S-wing balanced poppet).

Having acquired them for $35-55 each in various states, my plan is to offer them for $100. Despite how that sounds, after cost of poppet, spring, seat upgrades and rechroming/polishing, I'll lose about $5 per reg with no labor cost. They'll be "mint."

As readers have discovered, those of us that love them, really love them. PM me if you want on board. Even at $100, I expect they'll go fast.

Rob