8 core coily cable

[Jason Torbitt]

Incidentally I spoke with Howard today, and he told me that for some reason, he has been prevented from posting on the forum, so can't post a reply to this topic with regards to the MK-V coily post cable. I'm sure once this has been resolved, he will have some answers to the points raised in this thread, for those who are following this topic.

[Eric Fletcher S.O.C.]

Thank you Eric for your very consise answer. I have used the F900 extensively with my MK-V post and have never had critical issues but notice that the camera will shut down if I don't stay one step ahead of the battery meter on the camera display. Once it's at three bars, I change batts. I also use 1 hytron 150 instead of the Hytron 50's. This being said what are the dangers with the MK-V post as I power the F900. I would also assume that if I presently have 22 AWG in my post, an upgrade to 20 AWG is at least a good start.

 

 

Well, here's part of the issue, the 2B 308 Lemo used by GPI and MK-V can only accept a 22AWG wire. That's why XCS and Tiffen went with different centerpost plugs.

 

The Dangers of Powering a HD camera on a 22AWG wire is that the resistance goes up on the wire with temperature, and as you pull more than rated amps you increase the wires skin effect which increases the temp which increases the resistance which increases the voltage drop which increase the amp load... and that increase the wires skin effect which increases the temp which increases the resistance which increases the voltage drop which increase the amp load, and on, and on, and on. It's called a cascade failure. (It's also why NiMH battery chemistry is so bad same thing happens)

 

In the end you CAN power the HD camera off the smaller wire but you will have to accept the shorter battery life.

 

I had a Pro II with the MK-V center post conversion and when I did a long show with a Genesis the rapid battery depletion was killing us, that's what prompted my change over to XCS.

[Eric Fletcher S.O.C.]

Eric-

 

Again, excellent analysis/explanation.

 

FYI, to be accurate, all the Ultras use 14 gauge wires for power, always have.

 

Also 5 separate coax's for regular video and HD component (4 down, one return).

 

One of the five in the Ultra 2 is a special coax (larger, special connectors/no breaks) for HDSDI, and a data communications line!

 

Jerry

 

 

Jerry,

 

I corrected the wire size for the U2 and the XCS Ultimate both are running 14awg wire which is the correct size for this app.

[Alec Jarnagin SOC]

Kelly and Jason,

 

I beg to differ. Howard posted ONE reply to Eric's post. It had no technical correction or technical information for that matter. It merely blasted a member of this forum AND contained foul language. If Howard wishes to post a technical correction, I assure you that I would not delete such a post and I'd have great issue with any Moderator that did.

 

Thank you.

[Alec Jarnagin SOC]

"the 2B 308 Lemo used by GPI and MK-V can only accept a 22AWG wire"

 

I use an XCS post with PRO II connectors and therefore the aforementioned 2B 308 Lemo. XCS still uses its 14 gauge cable in this version of their post so one can certainly use this thicker gauge cable with this connector BUT you will experience some voltage loss in the connector. This loss is obviously not regained on the other side of the connector, but it seems to help to have the bulk of the run made from this heavier gauge cable.

 

A note to PRO users. The fact that you are using a two stage post (this is also true with XCS) means your cable run is much shorter than any four stage post. In short, if your sled has been working for you, don't panic. The circuit breakers on the PRO are also rated at 10 AMPs which means they will pop if you exceed this limit. One solution for these power hungry cameras is to have a "Y" cable made to split the load between your camera power line and your AUX line.

 

Cheers,

[Iain Baird]

The MK-V conversion actually uses a 3B.308 to the 2B.307 which doesn't have the aux power run through it. So the Y-connector option is not available.

[Eric Fletcher S.O.C.]

The MK-V conversion actually uses a 3B.308 to the 2B.307 which doesn't have the aux power run through it. So the Y-connector option is not available.

 

 

That's another reason I ditched the MK-V conversion. Ditching that Aux pwr line is a REALLY bad idea. Panavision wasn't happy about it either.

[Jaron Berman]

Jerry - I just posted this elsewhere (mods - feel free to delete), but in discussion with Robert, he pointed me to a post you made a while back dispelling the rumor of undersized connectors on Steadicams. Problem is - the U2 has a cam power connector .2B (correct?), whereas the clipper 2 rig I own has .0b cam power. The connector itself supposedly has an 8A rating... is this ok for tricked F900 or F23 use? I'm looking to have it replaced with the .2B connector, but in your opinion is this necessary? Thanks!

[Jerry Holway]

Problem is - the U2 has a cam power connector .2B (correct?), whereas the clipper 2 rig I own has .0b cam power. The connector itself supposedly has an 8A rating... is this ok for tricked F900 or F23 use? I'm looking to have it replaced with the .2B connector, but in your opinion is this necessary? Thanks!

 

Jaron-

 

You are correct about the U2 with a Lemo 2B 303 connector which is rated at 17 amps; the 2B 308 connectors mentioned in other rigs are rated at 10 amps. When I wrote the other post, I was thinking of the original Clipper (I think I was thinking) with the same stage as the Ultra 1, therefore the same connectors. The later Clippers with the new stage use smaller connectors but have the same size power wiring harness.

 

The 0B 303 connector is rated 8 amps, so it will be less efficient than the larger connector. I would not recommend running a Genesis all up (13 amps or so, I think), but it should be fine with everything else. You have lots of "headroom" with the voltage off the lithium batteries (fewer amps required). I don't think it's worth changing the connector (not sure it can fit, either).

 

Hope this helps....

 

For others with questions, download the LEMO Unipole/multipole catalog from Lemo.com and look at page 45-49 for amp ratings. The whole power issue is more complex... how may connectors are in the line, the draw, how close the connectors are to each other. Test it in the field.

 

Jerry

[Jaron Berman]

good advice, and thanks for the speedy reply! Back to cable making with 0b shells

[JimBartell]

One other thing to factor in is that current ratings are based on continuous loads, not intermittent loads. Basically, when current flows through any conductor it generates heat. Current ratings are based on how much heat will be generated by a continuous current and whether the insulation can handle the heat. That is also why the current ratings differ for wires when confined with other cables vs. being in free air as Eric pointed out. So whether the load is of short duration, such as bringing a 435 up to speed, or continuous, like a Genesis, also affects the rating.

 

Basically, it is OK to overload a connector as long as the duration is short.

 

Jim "intermittently loaded" Bartell

[Jon Beattie]

Having a thicker guage wire running through your post will help with the drop off. Even with having to step it down for the lemo connectors. Wouldn't you have to say that the more power hungry cameras are an issue because of the voltage draw they have? A thicker gauge wire is a key piece to the puzzle giving your batteries a break. But isn't a voltage amp at the top stage worth considering? Marell makes a 24v-30v amplifier http://www.marell.co.uk/converters/PC-2430/ . Amplifying your voltage will still make your batteries run out quicker, but it should help with cutting down on camera going down.

[Iain Baird]

In fact two A/B batts at full charge give off +30v and then make their way to 24 so I'm not sure if the Voltage Amp would help.

[Eric Fletcher S.O.C.]

Having a thicker guage wire running through your post will help with the drop off. Even with having to step it down for the lemo connectors. Wouldn't you have to say that the more power hungry cameras are an issue because of the voltage draw they have? A thicker gauge wire is a key piece to the puzzle giving your batteries a break. But isn't a voltage amp at the top stage worth considering? Marell makes a 24v-30v amplifier http://www.marell.co.uk/converters/PC-2430/ . Amplifying your voltage will still make your batteries run out quicker, but it should help with cutting down on camera going down.

 

Well, you are assuming that the converter is 100% efficient, it's not. and in order to boost the voltage it's having to draw more amps in order to get the higher output. in the end your batteries will deplete faster.

[Eric Fletcher S.O.C.]

The MK-V conversion actually uses a 3B.308 to the 2B.307 which doesn't have the aux power run through it. So the Y-connector option is not available.

 

 

No it doesn't, it uses a 2B.308 at the base of the center post and a 2B.307 at the upper d-box. The photos on the MK-V site show that. That includes the photos of my rig that I shot that Howard doesn't have permission to use... What else is new...