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Comtek BST-25/216 on battery power?


Johnny Karlsson

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What are you using out there for battery power with the base station?

 

I've only used it with AC, but would be good to have an option handy at times when this is not a viable solution.

 

The manual states "Power Requirements: 12 Volts DC, 300 mA max". It's not clear to me if this 12v requirement is such that one would need a regulator keeping it at precisely 12v when using a NP-L7S with a cup-to-4-pin XLRF, such as the one from PSC:

http://www.locationsound.com/psc-fpscpsm-np1-4pxlrf-np-1-battery-cup-with-4-pin-female-xlr-3576

 

Anyone with experience doing this, please let us know. Thanks.

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I ran my Comtek Base Station on the cart using my cart power supply for years and years. The power supply that I built is not regulated when on batteries alone but is regulated (nominal 13.5 vdc) when on AC. I never had any problems but it certainly isn't proof of what voltage variable/range is the actual specification. A more detailed spec would be helpful (like "Ext. DC 9 to 14 vdc") which most manufacturers publish. 

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If the heat and wildfires haven't knocked out the phone service in So.Cal., may I recommend you call and ask Comtek's tech department.  I've typically found them booth forthcoming and helpful, and the odds are pretty high they'd know more about it than most anyone. 

 

It's doubtful you need external voltage regulation, but it would be nice to know what Comtek specs as the allowable voltage range. 

 

However, it's pro gear designed to play nicely with other pro gear, so I wouldn't sweat it.

 

 

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Thanks guys, much appreciated! 

 

JW, I agree - most manufacturers spec a range, and this is why it got me a little concerned.

 

Yes JB, I will try calling them when I get a chance, to get their perspective and actual specs. I've also had nothing but a great experience calling Comtek in the past.

 

It's great to hear first hand experience from the field though. Everyone here knows what a NP-L7S is, and that it can spit out upwards of 16v when fresh off the charger, then hovers in the 14.x range...

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  • 2 years later...
On 8/10/2018 at 9:28 AM, Johnny Karlsson said:

Thanks guys, much appreciated! 

 

JW, I agree - most manufacturers spec a range, and this is why it got me a little concerned.

 

Yes JB, I will try calling them when I get a chance, to get their perspective and actual specs. I've also had nothing but a great experience calling Comtek in the past.

 

It's great to hear first hand experience from the field though. Everyone here knows what a NP-L7S is, and that it can spit out upwards of 16v when fresh off the charger, then hovers in the 14.x range...

I have the best 75/216 and use a np1 into a 12v regulator..... runs all day long

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7 hours ago, nevo said:

I have the best 75/216 and use a np1 into a 12v regulator..... runs all day long

 

 

On 8/12/2018 at 8:06 PM, nevo said:

I run mine off a Np1 with a 12 v homemade regulator...... 1 batt lasts a full day 

 

Would you guys please share with everyone what regulator you are using? Thanks

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On 9/3/2020 at 9:12 AM, Johnny Karlsson said:

my tech guy just built one into a Xlr barrel for me will take up to 30 volts in and outputs 12v

It’s a simple transistor and zener diode

Would you guys please share with everyone what regulator you are using? Thanks

 

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Thanks guys.

 

Well, around the time when I first  started this thread, I had a highly trusted repair tech at one of our usual suspects make me a BDS-to-4-pin XLR cable specifically for use with the BST. He looked into the whole thing and concluded that it would be fine without a regulator. I measured the output at the 4-pin and it indeed shows the same voltage as a Lectro SRC connected to the same BDS displays.

 

It is actually running fine, so I should perhaps not worry - but still.... the uneasy feeling I got from that email Straight Outta Comtek!

 

So I've been looking at several different buck converters/regulators and have contemplated one with an automatic voltage input range of 8V-40V. With 95% efficiency claimed, I even considered putting one between the battery cup and the BDS to have everything comfortably running at a steady 12V.

- Of course, then there would be no indications of remaining battery level left at any given time, and also I read some old threads here, as well as elsewhere mentioning it's common to get pretty bad RF spray from regulators and/or putting diodes in line... so yeah, right here on public display is me arguing with myself and haven't pulled the trigger on a regulator yet, because I'm still not sure if it's worth having one LOL.

 

 

 

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Yeah it’s a toss up. I think the guy at Comtek is pretty committed to the EXACT best case recommendation for the design spec of the unit so probably a steady 12 Volts is best. I think if you’re running a Meon or PSC system at 13.8 or whatever I wouldn’t worry too much I mean hundreds of mixers are using Comtek transmitters powered this way without any issues. Maybe the unit dies after 25 years instead of 30 but would that really matter to you? I would be a little more concerned if your DC setup is running a higher voltage like an NP1 based system would and that’s where you might want a regulator. Of course, that’s also the situation where you want it more compact and adding more crap to the rig is pretty unwelcome. I’m totally speculating here and there are plenty of mixers who power these with NP1s without any problems so it’s really up to you. I have done it on occasion as well. 
 

I find it a little irritating that Comtek doesn’t back this statement up with a little more factual info. When I pressed them on it the reaction I got was sort of “ no, it needs 12 volts, it’ll keep up with a higher voltage for awhile but...” but no real explanation of what might happen or when. 
 

Check out the brand Samlex if you do go down the regulator path. They make fully enclosed power supplies and regulators and etc that are popular with HAMs so noise specs and EMI should be good. I wouldn’t trust amazon cheapies. They also have isolated models which could help if you were having a ground loop issue somewhere which I currently am with my video monitor.  They have a unit about the same size as a BST75 that will accept any input voltage we would use and output 12.5 @ 8amps or something. I haven’t used one but thought about buying one and putting a hotbox on the output side to power any fussy 12v stuff on the cart. It’s kind of too bad the off-the-shelf power distros from RA and PSC don’t include a few regulated and isolated outputs. 

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