Looking to set up small system

Larry · Post by **Larry** » Wed Apr 28, 2004 5:50 am

Hi,
This forum has been so helpful in the past. I'm looking for some information on what I'll need to set up a small repeater system that will cover about a 10 mile radius... Need some simple info on how high I'll need to place my antenna and the minimum power needed for reliable coverage. Currently we are using a MCS2000 40 watt mobile UHF radios as a base with a magnet mount antenna and the same radios mounted in trucks with NFO mount antennas... we're getting about 1 1/2 mile coverage from mobile to base... we need to increase range... any help or suggestions would be greatly welcome.

Thanks

SlimBob · Post by **SlimBob** » Wed Apr 28, 2004 9:52 am

You seriously have something wrong with your existing setup. 40W should be enough for 30 miles, if not 45.

Post by Pj » Wed Apr 28, 2004 10:20 am

I'd get rid of that magnectic mount today, and put up a normal antenna. That's most likely half your problem right there.

CTAMontrose · Post by **CTAMontrose** » Wed Apr 28, 2004 10:38 am

that reminds me of the LTR system my old job used to have, the base antenna was a mag mount antenna zip-tied to the wooden coat rack in the office...

Jonathan KC8RYW · Post by **Jonathan KC8RYW** » Wed Apr 28, 2004 11:06 am

The base antenna: I'm guessing it's on a file cabinet or something, if it's a mag mount. Get the antenna outside, like PJ said. Depending on the run, I'd suggest using at least LMR-400 feedline.

Also, you might consider using 1/2 wave antennas on the mag mounts on the mobiles, as they don't require a groundplane. They also provide more antenna gain, over a 1/4 wave. They also cost more. Perhaps you might just buy a few, and see if they make an improvement.

If you bought these from a 2-way shop, I would avoid dealing with them again.

Susan157 · Post by **Susan157** » Wed Apr 28, 2004 11:49 am

well if the mobiles are not doing the trip
now.
you have a number of things to look at.
Will anyone do the HAAT numbers?

If you do not get the range now?
Then test out the equipment if the
HAAT is ok. (Height Above Avg Terrain).

These radios should work BUT were they
tested and set-up?

we need more to give more.

Cowthief · Post by **Cowthief** » Thu Apr 29, 2004 12:08 am

Hello.

I can do about 7 miles direct with a talkie, so something is wrong.
Is the base inside an all steel building? mobile home/office buildings make for really bad radio if the antenna is inside.
The mag-mount is not the greatest, but what about the coax, if it gets damaged, like in a door, this will also affect range.
This reminds me of the 70s CB era.

Larry · Post by **Larry** » Thu Jul 29, 2004 10:30 am

The set up I have for a mobile install is:

MCS2000 UHF 40 watt radio
Comtelco 5/8 3dbi gain antenna drilled and mounted in the center of roof SWR measured 1.2:1
10 ft. LMR 400 cable from radio to antenna

The base unit is on the second floor of a 3 story building:

MCS2000 UHF 40 watt radio
Comtelco 5/8 3 dbi gain antenna mag mount, mounted on a 2 ft. x 2 ft. steel plate, outside the building on balcony. don't have an SWR reading, it wasn't measured.
17 ft. LMR 400 cable from radio to antenna

Currently I'm able to TX/RX from base to mobile with a range of 2 miles in a heavily tree'd and suburban evironment (2-story wood homes). The base location is slightly lower in elevation... the terrain in not flat.

From base to portable my reception range is approximately 1 mi. or less (portables used are Astro Saber 3's and HT1250's... neither portable seems to TX to base with any better result... The portables will RX base at distances greater than 1 mi. but the base will not RX portable. I haven't checked range on portable to mobile yet... This whole situation may be just the location of the base, due to the lower elevation... but I was hoping for better performance.

thebigphish · Post by **thebigphish** » Thu Jul 29, 2004 11:27 am

I'm leaning towards that base station location as being the prime problem, the setup sounds at least 'acceptable'. if the base station is lower than the surrounding terrain, you're shooting all that RF directly into the trees and buildings...if you can get that antenna up, you should note a marked increase in distance...i'm kind of suprised the mobile doesn't burn thru it on simplex tho...:-\

Will · Post by **Will** » Fri Jul 30, 2004 6:53 pm

Heck, we talk halfway across so. LA County with 50watts UHF
... mobile to mobile!!!! 20 to 35 miles or so.

KG6EAQ · Post by **KG6EAQ** » Fri Jul 30, 2004 8:16 pm

Will wrote:Heck, we talk halfway across so. LA County with 50watts UHF
... mobile to mobile!!!! 20 to 35 miles or so.

Yea I talked with you simplex one day my whole trip from Pomona to about Sylmar. A good 55 mile trip.

Larry · Post by **Larry** » Tue Aug 03, 2004 11:22 am

After researching the site location
Lat: 42.1455193
Long: -71.0179062

The HAAT calculation was determined to be 107ft. above average terrain.
The antenna is mounted approximately 20ft above the ground.
The building which it is mounted next to shadows the antenna, the building height is 40ft. The area has lots of large trees and is fairly hilly terrain....

Since moving the antenna isn't an option at this property I am trying to find repeater site locations.

I am currently researching to see if I can locate a site which I can place my repeater. After contacting several radio dealers/service shops, and radio clubs I haven't found anyone that offers a site which I could rent for placing my repeater...

Hoping for some suggestions or alternatives...

Looking to set up small system

Looking to set up small system

Welll did any one do the HAAT numbers?

Range.

HAAT Calculation....