Batboard

i have a 22 story hotel that i am going to be doing a system for. I was wondering what is the best floor to but the Motortrbo Repeater. Is it better to put it in the centre of the building and run a 50/50 splitter one going up and one going down, or is it better just to place the repeater on the 2nd floor and go all the way up to about the 18th floor or so. I am using a 1/2" foam heliax cable. How may antenna should i use and what type of antenna should i use??????

Thanks in advance

John

Ah yes, the poor man's BDA - repeater in the middle and two lengths of coax. (big smile)

I've done it couple ways and they worked well with a few dead spots in the basement service area, and spotty coverage out on the street. If this customer goes digital mode, they may see even better performance than a standard UHF user.

Method One in a downtown historic hotel used RG8 terminated in standard mobile quarter waves under the theory the RG8 is leaky enough to act like an antenna the entire length despite the inherent losses. Splitter at the GR repeater in an electrical closet about half way up, two 100ft lengths of RG8, one up, one down, pulled through the existing vertical chase as far as they would go into ASP7A antennas sticking out horizontally from the wall of the closet they landed in. The customer used p1225's. Laundry was in the basement, but housekeeping was on the top floor. It was a little difficult for the radios to work in the basement. Covered the rest of the hotel just fine. Security had no complaints.

Method Two in a new university medical office used LMR400 terminated in salt shaker low profile antennas on Maxrad NMO mounts that have the ground plane rods and a wall mount bracket (don't recall the model - it's in Tessco). Same concept - repeater about midway up with a splitter - two antennas on each run separated about equal distance through standard tee's with one ant on the roof and one in the basement on a slightly longer run to reach it. Basement coverage was important as well as some distance from the building so that facilities personnel could be off premise. Security worked 800 off the city system. Coverage was adequate with no dead spots.

Method Three was a restaurant supply distribution center that covered a couple acres under the roof and needed coverage in all the different coolers and freezers for their lift trucks and pickers. I put the GR on the outside wall of a centrally located cooler, ran LMR to a four way splitter - one to a 3db gain at the top of the cooler wall which served the main warehouse, and the other three lengths of LMR to salt shaker antennas dropped through the ceilings of the different freezers and coolers which were like huge drive through farraday cages. Worked pretty good.

Why not just use 1/2 leaky hardline and splitters??

I think that you will find the coverage of the TRBo to be outstanding. Where once you may have some static or picket fencing, on the trbo (or most any digital system) it will be crystal clear.

In my case it was all about cost. We've done numerous real BDA's and diversified coverage systems using 1/2" and 7/8" feed lines into both distributed antennas and radiax for customers who can afford it. Some of them are to augment the city 800 and the cell bands deep into underground parking structures and highway tunnels. Some of them are strictly to extend customer coverage into the bowels of their buildings where no coverage exists like shopping malls and hospitals. But, most customers just don't have the money to do that. They tried simplex, and that got them 60% of their property. They bought a repeater and that got them to 90%. Relocating the repeater just changed where the missing 10% landed, and it was always an important 10%. Centrally locating the repeater and spreading the antennas out is a cost effective way to increase coverage especially if the class 2 wire chases already exist. 100-200 ft of LMR is an insignificant loss at UHF for the distance to be covered. It will put energy where it needs to be and raise signal quality easily and cheaply.