Portable Repeater suggestions?

bellersley · Post by **bellersley** » Wed Sep 28, 2005 9:57 pm

Hey gang. I need to put together a portable UHF repeater. It'll be comprised of two M10 UHF mobiles connected with a RICK like device (found here: http://www.batlabs.com/maxrpt.html). The RF will be going through a Sinclabs mobile UHF Duplexor.

Anyway, I want to make this as portable as needed. I'd like to build it into one of those aluminum tool cases (here: http://www.pacecases.com/images/Aluminu ... 01.TCT.jpg).

Does anyone have any suggestions as to how to run RF and Power? Ideally, I'd like to make it all self-contained, that is, have a 12V battery onboard, and mount an NMO mount somewhere on the top (maybe install a metal plate on the inside of the top section for a ground?). I'd also like to have the option to attatch an external power source and an external antenna if needed.

Thanks for any advice!

PRR · Post by **PRR** » Thu Sep 29, 2005 5:53 am

Just a few quick thoughts:

First, I would recommend a Pelican case (or one of the other manufacturer clones such as Storm and SKB) instead of an aluminum type: They don't deform as easily and thus remain watertight and dust tight longer. They have a variety of sizes and internal mounting plates. Uses silicone sealaent for mounting bolts protruding to the outside of the case.

Second, make a recessed plate on the side of the case for your antenna and power connectors. Use silicone on the flange and then nut and bolt liberally to form a water tight seal (except for the connectors themselves) Decide on an orientation for the case that will be "up" during operation and use a rubber flap (captured by the bolts holding the connector plate) to cover the connectors. (Best not to have the case's seam be upright when in the operational position.) Again, use silicone on the 'hinged' side of the rubber flap.

Third, look at the Neutrik PowerCon connectors for AC power http://www.neutrikusa.com/content/Produ ... =204_54471 and the 2 pole SpeakCon connector for your auxilary DC input http://www.neutrikusa.com/content/produ ... =204_54361.
And of course, an N connector for the antenna - I prefer panel mount to bulkhead. Use silicone on the perimeter of all connector mountings.

Lastly is the consideration of a fan. If weather proofing is a secondary concern, I always advocate forced air cooling with proper intake AND exhaust. Obviously this would render waterproofing ineffective, though so does any type of ventilation opening.

Both ventilation openings, whether for a fan or not, should have a hard protective screen or grate with a medium density foam (density to be based on fan's CFM rating or passive cooling flowrate). The screen/grate protects against hard objects from entering, the foam keeps dust and water spray out. If using a fan, the exhaust side should have a rubber flap mounted in the same manner as the protective flap over the connector plate.

A couple of other points: I highly recommend using a remote antenna, even if only a mag mount: This gives you the ability to get the antenna as high up and as far away from obstructions as possible without having to worry about the size and weight of the repeater case. Use a 'no ground plane required' type. Having an antenna mount on the case in a location favorable to directly attaching an antenna will leave it open to physical damage, dirt and possible corrosion when being transported.

My initial battery suggestion would be a gel cell type since they can be oriented in any direction. Hopefully RKG could chime in with a more detailed suggestion.

Hope this helps.

Henry

RKG · Post by **RKG** » Thu Sep 29, 2005 6:32 am

Definitely gel cel. The question is how large, and that depends on average current draw, peak current draw, anticipated duty cycle, and anticipated still time (length of the exercise). Most likely, the battery(ies) would have to be external to the case. Remember, only 50% of the nominal capacity of the batteries (in AH) is usable.

I would also recommend a TruCharge (Xantrex) charger. This will quickly recharge a battery that has been deep cycled; it will maintain batteries in their best condition; and it can be used as an AC source when AC is available (by connecting to batteries, which are connected to DC load; never connect a charger solely to the DC load).

Now, for some ballpark calcs:

Assume: the repeater works in one direction only; the Xmit radio is 25W nominal, and its key down current draw is 50W; both radios draw 10W when receiving and 3W when squelched; duty cycle is 5-95.

This works out to a weighted average draw of about 1A @ 12VDC.

Now, a 12V alarm panel battery (which is usually sealed lead acid, not gel), has a nominal rating of about 7AH, so you might figure that you could use one of them and have a 3-3.5 hr. still time capability. Not so: when xmitting, the draw of about 7A would drastically reduce the capacity of the battery. (The capacity of storage batteries is based on a load that does not exceed 5% of the nominal capacity at any time during the discharge cycle.) Figure that using the alarm battery would result in a still time capacity of just under 1 hour, with a significantly reduced battery life (in terms of lifetime cycles).

I'd opt for one Group 27 or Group 31 gel cell (about 80AH and 100AH, respectively). I'd box the battery in a separate case, with a TruCharge 20. Wire a 12V tap (through a 15A fuse using AWG 12 wire) to a suitable connector on the outside of the case, and wire the charger to an 110V-15A inlet connector on the outside of the case. The output of the charger is then connected to the battery terminals (no fuse is needed if the cable used is AWG 10 or larger, since the charger has a 20A circuit breaker in its output line).

Go to the scene. Unload the repeater box and locate, and set up the antenna. Run a DC cable from the battery box to the repeater box, and you're in business. As soon as a source of AC becomes available, run an extention cord from the AC source to the AC input of the battery box. Once programmed, the TruCharge is entirely automatic; as soon as it sees AC, it goes into the beginning of its three-stage charge routine.

I like to make battery boxes out of plywood with West System epoxy finish; this is reasonably weather proof (though usually the battery box remains in the vehicle) and it is entirely non-conductive. Also cheaper than anything commercially available (and there is little commercially avaiable for housing the battery and charger). Note that, if it is planned to offload the battery box so that the delivery vehicle is available for other assignments, bring along a 2-wheel hand-truck; the battery box, plus battery, plus charger will weigh 50-75 pounds.

Crimestopper · Post by **Crimestopper** » Thu Sep 29, 2005 7:23 pm

how can I post a few photos of my repeater....if you send me an email I can send you a link to my yahoo photos for some ideas. I'm making kits for next to nothing for other dealers. It can take the R1225 or M1225 mobiles setup plus some extras mounted in a nice pelican case. Help and I will show you my photos.

Later
Steve

chipjumper · Post by **chipjumper** » Thu Sep 29, 2005 8:55 pm

Optima yellowtops are like $130 from batteries.com with their never ending 20% off coupons and free shipping. Plus it has a pretty tough handle on it.

optima spec sheet

bellersley · Post by **bellersley** » Thu Sep 29, 2005 8:58 pm

Hi there. Thanks for the excellent ideas! I'm thinking I might just build it with a DC power outlet so I can power it from anything 12V, be it a car or a battery.

Crimestopper, you can reach me at [email protected]

Thanks again

Crimestopper · Post by **Crimestopper** » Thu Sep 29, 2005 10:46 pm

Check your email, you should have some cool pic's of my porta repeater....

Steve

bellersley · Post by **bellersley** » Thu Sep 29, 2005 11:28 pm

Oh now THAT'S the cat's ass! And, exactly what I'm looking to make. Can you provide specifics? Such as what kind of case that is, etc...? I don't know that an M10 would fit in the arrangement you've made because the radio is much deeper, but I don't see why it couldn't be adapted somehow.

Crimestopper · Post by **Crimestopper** » Fri Sep 30, 2005 10:30 am

are you talking to me.......did you like the setup? I'm building kits made to order you supply the radios...let me know if you liked it....I call it a THOR (Tactical Homeland Operational Repeater)....what flavor do you need?

Thanks
Steve

Crimestopper · Post by **Crimestopper** » Fri Sep 30, 2005 7:20 pm

How can I post pictures on this site? I have yahoo photos but I guess I need someone to host these pictures. Any input would be great.

Thanks
Steve

Garyf629 · Post by **Garyf629** » Sat Oct 01, 2005 5:56 am

Steve,

Would love to see your pictures. Just make your yahoo pictures a public sight, and post the link here.

bellersley · Post by **bellersley** » Sat Oct 01, 2005 1:50 pm

Steve;

Yes, I was talking about your setup. It looks pretty much like what I'd need!

As for my specs? Well, it'd be a single channel machine, UHF, with 2 M10 radios. Aside from that...I'm open to suggestions.

Crimestopper · Post by **Crimestopper** » Sat Oct 01, 2005 6:05 pm

turn the power down on the radios and make sure you have a good fan for heat build up. If you don't need a rick, I can make one for you. I can also offer GSA pricing since it is under contract with DOD. Thanks again...

Steve

Crimestopper · Post by **Crimestopper** » Sat Oct 01, 2005 6:08 pm

Here is a link

http://pg.photos.yahoo.com/ph/biker?det ... pg&.src=ph

here is a link of the build up

http://pg.photos.yahoo.com/ph/biker/det ... pg&.src=ph
http://pg.photos.yahoo.com/ph/biker/det ... pg&.src=ph

It comes in a pelican case, and I'm selling them made to order...battery back up is available of course patent pending.....

Thanks
Steve

chipjumper · Post by **chipjumper** » Sat Oct 01, 2005 8:00 pm

Whats with the e-stop next to the cooling fan vent (first picture)?

mancow · Post by **mancow** » Sat Oct 01, 2005 8:49 pm

Look again at the pic of the back of the panel.
It's a red plastic dust cover on the RF connector.

mancow

Crimestopper · Post by **Crimestopper** » Sat Oct 01, 2005 9:29 pm

Yep, the red plug is just a cover for the N connector......So what do you guys think? I'm building two new ones that will use the CDM750 and one that will link a GR1225 and a M1225. Any input or suggestions or criticism would help. The guy in the picture is a close friend. I'm pretty lucky on my pricing, I'm selling them new with battery back up for $1995.00 each(OUCH), got to love GSA sole source pricing. Please give any input or suggestions since this is my first protype.

Thanks
Steve

I can sell plain units and you can put the radios you want. This one does NOT have a rick, just a quick hookup to the 16 pin (COR, PTT, Etc...)

Crimestopper · Post by **Crimestopper** » Sat Oct 01, 2005 9:33 pm

I had two questions on painting.....on metal or alum, you need to prime first...

http://pg.photos.yahoo.com/ph/anytimera ... pg&.src=ph

Here is a pic of the prime job. HOWEVER, I'm now getting the metal plates dipped in black, looks nicer then my job.

here is another pic with a car with over 19 antennas, it is used for bomb jamming..

http://pg.photos.yahoo.com/ph/anytimera ... pg&.src=ph

mancow · Post by **mancow** » Sun Oct 02, 2005 12:21 am

bellersley wrote:I don't know that an M10 would fit in the arrangement you've made because the radio is much deeper, but I don't see why it couldn't be adapted somehow.

M10, is that based on the same frame as the other radius/maxtrac units?

If so, it should work fine. Remove the two allen head screws and pop off the front. There's enough cable there to make a 90 degree bend and the front of the radio body is still sealed by a metal panel inside.

mancow

Crimestopper · Post by **Crimestopper** » Sun Oct 02, 2005 1:45 am

Mancow is on the money.....it is nice way to do a flush mount. Underneath, mount your M10. Saves you money on cutting big holes. Your M10's should fit fine in a Pelican.

Later
Steve

chipjumper · Post by **chipjumper** » Sun Oct 02, 2005 5:59 am

I see these are mobiles; how much use can they take until overheating???

Crimestopper · Post by **Crimestopper** » Sun Oct 02, 2005 2:16 pm

I have them running at 10 watts and they can run all week with out any overheating, plus the super fan works great in sucking out the hot air. Lets be honest it is not always how much power you have for performance. It comes down to proper cables, tuned duplexer, and a great antenna.