Info Clash of the Titans

[Capt Jim Wyatt]

Kind of a long story ..... I dive sidemount with two older grey Shearwater transmitters because when I bought these a few years ago there were no yellow ones available. I was aware there could be "clashes" / interference between the two. The workaround has always been to not turn them on at the same time. This has worked for me without fail for a long time. Until yesterday (4/30/24).

Preparing for the dive I set up both bottles, turned the valves on a few seconds apart and the Perdix AI read the pressures almost immediately with the brand new Energizer CR2 Lithium batteries I installed on the transmitters.

When I got in the water and put the tanks on I kept getting NO COMMS error messages alternatively between the two. I suspected "clash" between the two so I turned off one tank, purged the second stage, waited 15-20 seconds and pressurized again. Both worked fine for 30-45 seconds then NO COMMS messages again popped up. I went through this off/purge/wait/on again series of steps several times on both sides. They would hold good comms for a minute or so and then NO COMMS again. This went on for 10-15 minutes trying to establish good comms so as to dive, no joy. I aborted the dive and assumed the new batteries were bad.

Then went home, removed the batteries and measured the voltage at 3.0 volts, both batteries. I am not sure what voltage I should expect out of these brand new batteries. 3.4 maybe?

This morning I reinstalled the same batteries after being out of the transmitters overnight, placed the regulators on the tanks, pressurized them about five seconds apart and the Perdix AI caught the signals and displayed the pressure readings for 5 minutes or more and it seems all is well.

WTF

I *think* that the issue was the clash and I further think the clashes do not clear in a matter of 1-2 minutes??

Any opinions? Has anyone experienced this behavior?

 

[inquis]

Yup, happened to me on my last trip to Ginnie. I got all the way to the Bone Line before acting up. I did the reset dance several times, but misremembered the time and didn't wait long enough either. Buddy was wet & cold, so the early turn turned out to be a blessing in disguise.

The gray transmitters turn off after 2 minutes of zero pressure.

(This from the older SW manuals. The info in the current manuals assume the Swift.)

That said, 3.0 V on a new battery seems on the low side to me. The couple of spares I have sitting on the shelf are 3.25 V.

 

[tursiops]

Agree with the above. Need to wait at least 2 minutes for the timing to reset. The issue is that when you turn it back on, you might miss the good window and hit the clash window again.

 

[Capt Jim Wyatt]

Somehow I missed the 2 minute part....

Thanks for the replies.

 

[Capt Jim Wyatt]

That said, 3.0 V on a new battery seems on the low side to me. The couple of spares I have sitting on the shelf are 3.25 V.

Roger that.

 

[-JD-]

Or just stop worrying, get mellow, and go yellow ...

They do come up now and again and I've gotten them for no more than a grey one.

Still looking for a green one, though ...

 

[Belzelbub]

Honestly, while rare, this could continue to happen. It really depends on the actual interval between the two transmitters. IIRC, it's supposed to be 5 seconds between transmissions. It's really not. It's approximately 5 seconds. Individual circuitry tolerances will mean it's not exactly 5 seconds. So, one could be a bit under 5 seconds and one could be a bit over 5 seconds. Eventually, they may catch up. Which is likely what you saw as the NO COMMS didn't start immediately.

A low battery could be a contributor, but I wouldn't expect this will completely eliminate the issue. Having one of the transmitters be yellow or a Swift is about the only way to be sure.