Control station power supply/ups

[emtprt]

We are adding a UHF 40 watt control station in the penthouse of a regional dispatch center. The control station will be a backup for the main system if there is a phone line failure but will primarily be used monitor a seldom utilized administrative channel. The 19" rack is already present and a 40 foot lenght of hard line and a 9.2 db gain yagi antenna will be mounted to the roof top tower.

I received a price quote that seemed pretty steep for the projects power setup. The radio( a CDM1250) will be mounted in a r1225 style 19 inch rack housing with a preselector and power supply. There will also be a battery revert and trickle charging system with a bank of 3 batteries on a seceond shelf.

The center does have a generator and we basically just needs to keep the radio powered until the generator kicks in. If the generator were to fail the entire center would be off line and the console would be likely be inactive. In that situation all of the batteries that were quoted would power a radio that could not be controled.

My question is do I really need all of these batteries for 1 minute of down time or the occasional power surge. I think that a simple rack mount UPS would meet my needs.

We decided to go with the mobile radio setup to allow easy an equipment change over in the event of a digital upgrade or future 6.25khz bandwidth requirements.

Thanks
Mark

[Bill_G]

If it really is one minute for the gen to stabilize, and the transfer switch to kick in, for a seldom used channel I wouldn't put any backup at all on it. But, you're right a simple 200W UPS would carry you.

[emtprt]

The control station will have 2 channels programmed and our fear is the radio might revert to the wrong channel if there was a power interuption. When we first strarted using the CDM radios we did not have the ignition sense installed. When a vehicle was started the radios would end up doing some strange things ie; wrong channel, be on scan or an option would activate that was not selected when the vehicle was shout off.

We now keep the radios power hot at all times and use the ignition sense. There have not been any issues for 9 years.

Mygoal is keeping the radio alive for the minute or two that the generator needs to kick in and prevent the radio from changing channels. I could see the console status displaying channel 1 and the radio being on channel 2 if there was an interuption of power or a surge.

Thanks again for your input

Mark

[motorola_otaku]

I don't see why you couldn't spec and procure a setup like this on your own if you wanted to. The only thing I could think of that might be a little hard to obtain by itself would be the rackmount panel for the CDM radio.

For your setup I would go with an Astron SRM-18 rackmount switching power supply (rated 15A continuous and 18A surge, and even that is overkill for a 40W UHF CDM) and a Tripp-Lite Smart750RM1U rackmount UPS (rated for 450 watts, 24 min @ half-load, 7 min @ full load.) Both of those are orderable through Tessco and any reputable reseller should give you a several-percentage discount off list price. I know the switching power supplies haven't completely proved their mettle in the minds of some techs, but I have that same exact power supply running in a 7A continuous/14A occasional peak setup that hasn't given me any trouble for 2 years of 24/7 operation.

[emtprt]

I have a Tessco account and will check out the items that you suggested. The CDM mounting rack is basically being used instead of a sheltf to keep the rack clean. I am not able to do the connections or install at the site due site contracts, the console warrenty and liability issues. A Motorola dealer must do the install and there is a push to purchase through them. The only way around it is if I had equipment that was already inservice at another site that could be moved, which I don't have.

I do have a Motorola account and might be abe to purchase the rack. If I am able to do that I probably could provide the equipment for the site.

[tvsjr]

I know of several UHF LTR trunking systems running on the Astron SRM-30M-2 dual 30A supply (one supply for exciter/controller, one supply for PA... per channel) that seem to stay in TX 100% duty cycle from about 7a to 7p every day without any major problems whatsoever.

We're also using them on a large regional DSTAR buildout. Very nice supplies. I would have no hesitation using a good switcher these days.

The rack mount panel is, most likely, from Middle Atlantic.

If you don't want to drop the money on a UPS, and assuming you can do some things that aren't "industry standard", look at West Mountain's Super PowerGate. Basically, it's a 40-amp OR gate with smart charger. Hang a good sized 12VDC AGM battery (one of the standard ~80Ah batteries seen at any tower site would be more than overkill) on one input, power supply on another, and output to CDM. You could do the whole power setup for sub-$500.

And please, plan to service whatever battery arrangement you go with every so often - typically for UPSs, I use 12 months for critical and 18 months for non-critical systems. Pull battery out, install new battery, recycle old unit. It's cheap insurance.

[emtprt]

My price quote for CDM1250 control station with receiver preselector in
CDR500 housing, 19" panel mount, tone remote
adapter for CMED. 2700.00
Battery reverting charger with cables and 2 AGM
12vdc batteries and boxes w/lidson Rack shelf for batteries 2300.00
Install, polyphaser, jumpes 1100.00
So the install for the Control station would cost 6100.00.

If I purchased the items on my own Radio with 19" mounting rack 770.00
Power saupply 165.00
UPS 175.00
Cable 40" 118.00
Poly phaser 72.00
Preselector 380.00 untuned 530.00 tuned from EMR
Antenna already present from former contol station but cable
unavailable.
Labor
1100.00
Total cost 4400.00 using items purchashed on own with radio that we already have

[psapengineer]

If its a control station that's remotely operated by desk sets, are the desk sets or remote controls also backed up for power during the period from utility fail to generator online? Otherwise how do you know if the radio or the desk sets are on the "wrong" channel following the return of power?

[emtprt]

The current console setup has 4 positions; each position has a UPS and the computers and phone systems have seperate a UPS systems. The entire building has generator power (multiple units). The building that the center is located houses numerous agencies that require power in the event of a failure.