Scubapro Balanced Adjustable 156/109 with MK 18 2nd stage, a good idea ?

[scubafanatic]

I was looking for a decent backup/spare reg set, and bought my 1st Scubapro 1st and 2nd stages (Ebay today)

Mk 18 (described as excellent cosmetic and operational condition) $ 115
156/109 balanced adjustable (essentially new condition, freshly rebuilt with new diaphragm/poppet, etc.) $ 145 ( I just thought this 2nd stage looked COOL! )

both items together totalled $ 260, both items looked GREAT per their photos, and seller ratings were 99% and 100% positive feedbacks, both to arrive to me 12/12.

I've bought (and still own) many a reg set, but I'm new to Scubapro regs, so I'm hoping I made good choices at decent prices.

I saw a few decent-to-good looking MK 10 1st stages (and do own a pair of Atomics with very similiar 1st stages) but I decided to mate the 156/109 1st stage with a diaphragm 2nd stage (with LP port swivel turret) for this purchase, because I like the sealed diaphragm design better. Should I still hunt down a MK 10 st stage (and if 'yes', which one as I know there are a lot of variations within the MK 10 series), or is the MK 18 perfectly fine with no issues ?

...did I do OK ?

Karl

 

[Nemrod]

A Mk 18 will be fine with a 109 second. You will probably have to tune the 109 and the Mk18 for the IP, 135 is good.

N

 

[Fishpie]

As for the MK 10 the vast majority are all the same, the exception being the MK10 Plus which was only made for a brief period at the end of the series lifespan (along with some conversion kits).

Early 10's have the old style "banana" metal yoke nut and no waist.
Later ones have round plastic yoke knobs and a groove in the waist to fit a rubber boot to hold in grease....cold water SPEC when filled.
The Plus have different piston and seat and were a further cold water adaptation.
For water above 45 degrees it makes no difference which one and they all have the same (high) performance.

They can be the best performance bargain of all SP 1st stages.
The main caveat being opening them up for the 1st time to service if it's been many years since last service. Theres a couple of parts that need the be separated that can get corroded together over time. A careless tech could easily do some nasty cosmetic damage wielding a pin spanner.....but that can also be said for quite a few different regs as well.

It's been a few years since I played with an 18 but I don't remember it having a second "environmental" seal like the current 17.....again not a problem until the water is very close to being solid.

Have to agree with you about the cool factor of the 109/156BA.....has to be the E Type of the scuba world.

 

[scubafanatic]

As for the MK 10 the vast majority are all the same, the exception being the MK10 Plus which was only made for a brief period at the end of the series lifespan (along with some conversion kits).

Early 10's have the old style "banana" metal yoke nut and no waist.
Later ones have round plastic yoke knobs and a groove in the waist to fit a rubber boot to hold in grease....cold water SPEC when filled.
The Plus have different piston and seat and were a further cold water adaptation.
For water above 45 degrees it makes no difference which one and they all have the same (high) performance.

They can be the best performance bargain of all SP 1st stages.
The main caveat being opening them up for the 1st time to service if it's been many years since last service. Theres a couple of parts that need the be separated that can get corroded together over time. A careless tech could easily do some nasty cosmetic damage wielding a pin spanner.....but that can also be said for quite a few different regs as well.

It's been a few years since I played with an 18 but I don't remember it having a second "environmental" seal like the current 17.....again not a problem until the water is very close to being solid.

Have to agree with you about the cool factor of the 109/156BA.....has to be the E Type of the scuba world.

I'd opted for the MK 18 over the MK 10 because I was leery of a non-sealed piston 1st-stage (my 2 Atomics are sealed pistons). I don't dive 'cold' water, but do dive salt water, so I'm trying to reduce the impact of salt water corrosion on the 1st-stage innards, reducing the high maintainance factor. Also, I believe pistons need shims for IP adjustment.

I don't buy used/vintage items with the intention of being the fixer-upper 'tech' guy, I'll pay extra $ for items that can be used/vintage that are already serviced/great condition.

I was looking to build up a reg set with a metal 2nd-stage (limiting me to Mares and Scubapro), I wanted an Adjustable 2nd-stage, narrowing it down to Scubapro only, but somehow not really warming up to the look of the A700, so I wanted a new condition 'vintage' 2nd-stage reg...and as you say, the 109/156BA just looks cool !

 

[Nemrod]

The USD/AL Conshelf is all metal and frankly can kick 109 butt.

N

 

[scubafanatic]

The USD/AL Conshelf is all metal and frankly can kick 109 butt.

N

I don't think those 2nd stages are diver adjustable though. I also own a number of Aqualung Titan LXs though (the ones that were phased out after 2008, not the newest version) which are my workhorse regs that I've been quite happy with.

 

[Nemrod]

I don't think those 2nd stages are diver adjustable though. I also own a number of Aqualung Titan LXs though (the ones that were phased out after 2008, not the newest version) which are my workhorse regs that I've been quite happy with.

I have several sets of both, the Conshelf is easier to work on, less finicky on adjustment, easier to get parts for, flows more air and exhaust more easily due to the 30mm exhaust valve vs 25 for the 109. The Conshelf has a lower WOB and is equally rugged and simpler. The Titan XL is a plastic Conshelf and it too will kick 109 butt.

If I recall, the 109 (and the G250) got a 3 out of 5 on the ANSTI test at 75 RMV at 135 feet and the Titan XL a 5. The Conshelf is probably a 5 or at least a 4.5.

The 109 is prettier though, I give it that. Your 109s will do fine with the Mk 18 or as a friend of mine, with a Titan or Conshelf first. Mine have Mk Vs or clone Mk Vs. I prefer the clones.

N

 

[halocline]

I saw a few decent-to-good looking MK 10 1st stages (and do own a pair of Atomics with very similiar 1st stages) but I decided to mate the 156/109 1st stage with a diaphragm 2nd stage (with LP port swivel turret) for this purchase, because I like the sealed diaphragm design better. Should I still hunt down a MK 10 st stage (and if 'yes', which one as I know there are a lot of variations within the MK 10 series), or is the MK 18 perfectly fine with no issues ?



Karl

The MK18 is not a sealed diaphragm. It's a MK16 with a turret, not a MK17 with one. They are typically rebuilt with the newer MK11/17 poppet and function pretty much the same. I think it's a fine first stage and I don't think you'll have any sort of problem with it at all.

Other than the MK10+, all the MK10s are functionally the same, although as Fishpie pointed out there were some cosmetic differences. Even though the later SPEC models had the groove (good luck finding a boot for those!) you could still seal the earlier ones, it just might be a little messy. I've had excellent luck sealing my late model MK5s with the small ambient chamber holes, and overall I like MK5s better than MK10s. But that's more personal preference than any actual performance issue.

Here's an interesting point; neither the MK10 nor the MK18 will provide completely stable IP across the supply range. MK10s will drop a good 7-10 PSI from 3000 to 500 tank pressure, and MK18s will rise about the same amount. If your 109 has been refitted with a balanced poppet, you won't notice any difference. If you want really stable IP within a few PSI over the whole supply range, the MK15 or 20/25 is your ticket. I am a big fan of the MK15, but it has some disadvantages, namely a unique seat that's harder to find and it requires a specialized set of snap ring pilers to service. But it lasts a long time; I service mine on 5 year intervals at most.

If your 109 has been serviced expertly, which includes careful examination and possible replacement of the lever, all rubber parts, and the chrome is in excellent shape, I don't think $145 is unreasonable at all. It's kind of scary though to think they're that pricey these days; I don't think I've ever paid more than $30 for one. But that doesn't include the new parts.

Enjoy your new regulator, and I suspect if you get the right mouthpiece and hose set up for the upgraded/restored 109, you won't want to just use it as back up.

 

[Fishpie]

The only other metal 2nd stage with an adjustment knob is the Kirby Morgan Super Flow..........this is just a Conshelf 2nd stage with the knob added but their price and reputation doesn't reflect that.
It does confirm my and Nemrods assertion that the old USD 2nd stages don't get the respect they deserve.
btw all of the current AquaLung balanced 2nd stages (LX, Legends and Micron) are really an Apeks in a slightly different case and have remained unchanged functionally since their introduction.

 

[axxel57]

scubafanatic

As you probably know, the 109 has a big fan group in this forum,and whatever problem you might face with it in the future, you will find excellent advice here.

Concerning the Mk18, you might have to decide sooner or later (if it has not be done yet) to replace the old poppet - seat configuration with the newer one(MK11 - MK17).

If you should find in your MK18 the old configuration, you probably can find that out by just connecting your 1st to an IP meter. The old MK18 is a notorious creeper, if there is the slightest imperfection on the hard or soft seat,the IP will creep quite a lot.

If the imperfection is bigger it will override the 2nds.

I've been servicing a MK18 - D400 of a professional videographer now four times.

Since the service intervals were relatively short, and in between I had to change - clean the poppet - soft seat components, I suggested to change for the newer Mk11 -MK17 configuration what he agreed. With the newer configuration there is hardly any noticeable creep. So far so good.

That was in March, he has been working almost very day with it and last week I did a service again.

What I realized in the process of changing and testing was that with the old configuration there was the problem with the creep, but the balancing was excellent,just 2 - 3 psi difference between full and near empty tank.

With the new configuration the IP was solid,but the balancing even lousier than the one of the MK11 - MK17.

The difference between full and near empty tank is now 13-14 psi.

When I told the guy that, he decided to stay with the new configuration, because he did not expect much effect he might be able to feel while diving because of his very good 2nd stage, which I agreed.

So if your 109 should be still unbalanced and your MK18 has still the old poppet - seat configuration,you might want to hang on with it for a while until you got your 109 balanced, because an IP change of 13 -14 psi with the newer configuration (if it should be in the same range in your 1st stage), could easily translate in an increased cracking effort of about 0,3 inch/h2o.
That is a difference you probably will feel while diving.

In this case you would have a harder breathing regulator in the beginning of the dive, which breathes better and better towards the end of the dive.

If your 109 is already the balanced version, then you might look for a change for the new configuration for the reasons mentioned above.

Anyway, good luck with your new 'Baby'.