Hammerhead or Meghead?

[caveseeker7]

Tim, I know that the HUD signals the pO2 value with the number of flashes.

What I ment is that there is no secondary gauge which I consider worth mentioning.
A gauge allows you to see both the pO2 value of the cell as well as it's ability to
respond to gas changes in the loop, thereby give an indication of a cell's condition.

 

[trob09]

Tim, I know that the HUD signals the pO2 value with the number of flashes.

What I ment is that there is no secondary gauge which I consider worth mentioning.
A gauge allows you to see both the pO2 value of the cell as well as it's ability to
respond to gas changes in the loop, thereby give an indication of a cell's condition.

Gotcha. What's worth mentioning to one may not be to another.

FWIW the HUD provides the PO2 value of each cell in order and will respond to and illustrate gas changes in the loop. It is easy to see and verify cell performance for each cell via the HUD with a dil flush. The HUD will also provide a visual warning if a cell is tracking differently from the others.

Not sure if you knew that, but the HUD for the Meg does what you mention above -

 

[caveseeker7]

I didn't know that, nor do I understand how you can see it.

As I understand it, the HUD blinks, giving you the setpoint for one cell.
Then it cycles to the next cell and does the same ... so you can't compare
the cells side by side as on tripple readouts like the KISS or HH secondaries.

The cycling is continues, correct? You can't hold it on a cell to observe it over
a chosen period of time. That's the same on the MK16's secondary, which has
a digital number readout yet is still next to impossible (for me) to track.

And the flashes take a moment, then a brief break, then the next cell, so
how can you track the cell response?

Don't get me wrong, the ability and importance to watch what the cells are up to
is very much a personal preference, and I know plenty of divers who don't care
much for it. For myself it's something I want (and got ).

 

[trob09]

I didn't know that, nor do I understand how you can see it.

As I understand it, the HUD blinks, giving you the setpoint for one cell.
Then it cycles to the next cell and does the same ... so you can't compare
the cells side by side as on tripple readouts like the KISS or HH secondaries.

The cycling is continues, correct? You can't hold it on a cell to observe it over
a chosen period of time. That's the same on the MK16's secondary, which has
a digital number readout yet is still next to impossible (for me) to track.

And the flashes take a moment, then a brief break, then the next cell, so
how can you track the cell response?

Don't get me wrong, the ability and importance to watch what the cells are up to
is very much a personal preference, and I know plenty of divers who don't care
much for it. For myself it's something I want (and got ).

I too want to see what's going on. the meg HUD makes it very easy because it is constantly looking at each cell and reporting that info right in your field of vision.

There is a pause between each cycle of the HUD that is greater than the pause between each cell which makes it very easy to see and follow the cycle. you know which cell it is because it is the first, second or third in a series with a more defined pause separating the cycles. It continuously cycles through the three cells but takes at most 3 seconds for each cycle, It is very easy to start observing at the beginning of a cycle & watch how any or all cells move with a flush. If I want to watch the 2nd cell, I just focus on the second blink(s) in the series of 3. If I see blink, blinkblink, blink - pause - blink, blinkblink, blink (all green) I know that the second cell is reading 1.2 and the 1st and 3rd cells are reading 1.1. As I said, the cycle move quickly enough to track change in 1 cell or compare across cells.

The prism secondary is very easy to isolate 1 cell & watch it track, switch to another & continue so I can see how the meg's secondary might appear to be difficult but with a few minutes it is really quite easy to use and monitor the loop and each cell's activity. It is actually much harder to describe than it is to do.

Anyway, the prism is a fine unit, one that I gave serious consideration. I'm just defending the meg as it does what you suggested or thought that it didn't but in a way that might not be immediately obvious but becomes very obvious within the 1st pool dive.

Best,

Tim

 

[caveseeker7]

Thanks for sorting through that for me, Tim,.
I really appreciate that and take your word for it that you can easily enough track cell response.

As you pointed out, the PRISM only shows one cell at a time, and many in the tripple readout crowd belive cell tracking is hard or impossible. When switching the thumbwheel between positions the current is interupted and the speed with which the needle swings back up to the cell value is the indication of the cell's condition.

Much as on your Meg it's just a matter of getting accustomed to read it.

 

[trob09]

Thanks for sorting through that for me, Tim,.
I really appreciate that and take your word for it that you can easily enough track cell response.

As you pointed out, the PRISM only shows one cell at a time, and many in the tripple readout crowd belive cell tracking is hard or impossible. When switching the thumbwheel between positions the current is interupted and the speed with which the needle swings back up to the cell value is the indication of the cell's condition.

Much as on your Meg it's just a matter of getting accustomed to read it.

No problem Stefan.

Personal preference aside, the more informed we are about other rebreathers, the better off the rebreather community is.

 

[mattwave]

I don't get it. What's the big deal with the HH electronics, it seems so many divers are succesfully diving with stock electronics. Diving with a RB is unique enough, what makes the HH upgrade so valuable?

 

[BigJetDriver]

I don't get it. What's the big deal with the HH electronics, it seems so many divers are succesfully diving with stock electronics. Diving with a RB is unique enough, what makes the HH upgrade so valuable?

Matt,

There are several things that make the HH desirable. One is that it was designed as a deep-diving system, so the algorithm is set up to handle helium and deep stops effectively.

Another is the split handset arrangement. You have a totally separate unit driving the HUD, and until you have had a "shaker" warning from that unit, you will not understand how "positive" a warning system it really is.

Yet another thing is the vertical arrangement of the sensors, and the ease of which they can be changed. And finally, having the (optional) fourth sensor plumbed directly into the hat, with a feed to your HS or VR-3, is a real treat.

 

[caveseeker7]

Diving with a RB is unique enough, what makes the HH upgrade so valuable?

In addition to BJD69's points, the HH has a completely different layout.
Setpoint Controller:
- APD: two wired together
- HH: one setpoint controller, one separate pO2 monitor
-- left setpoint and dive computer
-- right handset pO2 readout for all three cells

Batteries:
- APD: one compartment for both batteries in loop, depending on age unsealed at ambient pressure (and shared in Vision)
- HH: separate batteries sealed at 1 ata outside the loop inside each handset

Alarm:
- APD: buzzer, implodes around 180 msw flooding the loop
- HH: vibrating alarm (DIVA)

Cables:
- APD: wires at ambient pressure inside hoses (Classic, anyway)
- HH: sealed waterblock cables

Displays:
- APD: Either twin handsets, no HUD (Classic) or single handset and HUD (Vision)
- HH: Twin Handsets and HUD with DIVA

Deco Software:
- APD: Either not available (Classic) or optional (Vision)
- HH: Standard (nitrox, trimix used to be but may change with O2ptima deliveries)

Price:
- APD: Upgrade to Vision incl. deco around $4,000 ($4,500 with scrubber gauge)
- HH: $3,000

Original Head (and cannister if scrubber gauge is ordered):
- APD: wants it back (they add the rest in new parts and resell the CCR at a lower price)
- HH: you keep it and thus have a backup

 

[bruehlt]

You know - it would be nice if anyone had links the the MH info....