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Comtek M216 / BDS Power


audiofp

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My M216 lives in my bag 100% of the time and I'd like to power it with the BDS. Comtek tech support basically came up with the same idea as me: Fashion a wood block to 9v battery dimensions, mount the appropriate terminals/wire and power it with a regulated 9v feed from the BDS.  I've looked at the ISO9VOLT but the connector is in the wrong place.  Before I put this together has anyone come up with another solution?  -Thanks

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If you really want to power it from BDS then get the Comtek BST 75-216

http://comtek.com/bst-75-216/

 

I use this on my cart and also in my 664 bag provides a much stronger and better quality transmission. I use the 9v powered TX in my 633 bag  

I am already charging Np-1 AA Sony L mounts and I power 9v for the comtek RX so charging one more battery is no big deal. 

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I use a battery eliminator, I got it from Location Sound in LA back in 2004. Can't remember what it cost but it has been very convenient for me. One power switch for the whole bag etc. 

Having another plug into my BDS is no big deal for me. Seems like infinitely less hassle than charging another battery every couple days. 

 

Best,

Dennis

 

edit - one hassle was I had to drill a hole in the batt door for the cable, took 10 min 10 years ago. no biggie. 

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I forget who it was (maybe Eric Toline?), but a while back I got the recommendation for this eliminator from either this board or RAMPS, and it's worked flawlessly for years. I just snipped off the wall wart, and added my DC connect of choice.

 

http://www.qcavionix.com/be-9.php?cat=20503

 

I had to file a small cable exit in the battery door, but it didn't require too much surgery

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One other possible issue is RF current getting reflected back through the power connection into the BDS.

 

I don't think there are any isolation chokes in either the BDS ver 1 or 2. Also, I don't know if negative battery ground ts at the same potential as the sleeve on the micro-jack input (Comtek doesn't make schematics available for their current products). Might be creating more grief than it's worth...

 

--S

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The BST has variable output if you get into any trouble. But 216 is far enough away from radio mics, that it should be ok.

 

Trying to keep my bag light for this tired old body.  The BST adds another 11 oz.  One of the reasons I shifted to 633/Stingray.  I'll probably go with the 216/BDS experiment for now.

 

 

One other possible issue is RF current getting reflected back through the power connection into the BDS.

 

The Comtek tech had thoughts on that.  We'll see.

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I'll second the ferrite collar suggestion. Almost all RFI/power issues for me have traced back to Comtek. They are a great company with great products, but their designed application (originally) did not require the same sort of power issue considerations we need for our application.

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I use these for Comtek powering, both on the cart and in a bag:

 

http://www.qcavionix.com/be-9.php?cat=20503

 

It requires that I file a small rectangular hole for the cable to come through on one side of the Comtek where the door and the housing meet.  For use with the M216, I also file the outside of the battery eliminator's case a bit to make it fit well.

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The choke is part of the XLR connector assembly on the input. Newer Comtek input cables have a nice little inline splice box.

 

I have the schematic at the shop. can look it up if needed.

 

However, this does not address any possible RF current flowing through the power connection. It only helps reduce RF from getting back-fed to the audio source. (And even with that, there is still some leakage).

 

--S

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Hi all!

 

I've used a Dremel to drill a small opening for the DC input into the M-216's battery door right next to the hinge. This allows me to use an old Sennheiser 9V battery eliminator (model DC-1) that was originally intended for use with the first generation Sennheiser Evolution G1 transmitters or receivers. Input voltage is 9V to 18V and it delivers a constant 8V at 200 mA. Works great with the Comtek.

post-1504-0-68559200-1394709411_thumb.jp

post-1504-0-10696200-1394709420_thumb.jp

post-1504-0-33987700-1394709429_thumb.jp

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I went with the QCAvionix Battery Eliminator.  Nothing is easy- it's slightly deeper so I'll have to accommodate that.

 

 

For use with the M216, I also file the outside of the battery eliminator's case a bit to make it fit well.

 

Where did you shave- the back of the eliminator, front or both?

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I was sent this schematic a while back when I was trying to rebuild my comtek cable.. It has an exploded view of the choke..as well as the resistors at the connector end. I rebuilt this cable with a ta3 end for my 664 with all the resistors inside the connector.. pain in the ass! I use a ferrite choke at the other end because I didn't want to make any cuts in the cable to make their version of the choke.. So far so good.

cable_diagram.pdf

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