uhf repeater antenna replacement

[emtprt]

I am replacing my dipole array 4 bay antenna due to ice creating problems. I need a 7 or 8 db gain omni directional fiberglass replacement. I do have budget limitations and would like to get the most bang for my buck.

The Laird line is inexpensive and on paper sound good but I have heard of failures in windy situations. I have used Comtelco in the past but they do not make anything over 6db gain.

The site is 400 feet above sea level on a 6 story building. Wind has been an issue.

Any ideas?

Thanks

Mark

 

[davidgcet]

before you go with high gain, check your license. your EIRP limits the gain allowed. if you allowed 100W and use a 50W repeater, then assuming no feed line loss you can only run a 3db antenna. it is rare to see someone busted for this, other than when causing interference, but has happened.

as to your question, i don't like the cheap antennas for repeaters. they are fine for a base, but the repeater is the heart of your radio system and you need to do it correctly. at least plan on spending 750-1000.00 for a decent antenna.the RFS-1151 antenna is a great 8 db omni and runs around 1000.00. if you must stay cheaper than that, then go with the Laird since at least you won't have to pay for a climb if it goes bad.

 

[kb0nly]

Is this Ham or Commercial/GMRS or what?

 

[prcguy]

I was in the repeater business for many years and for commercial repeaters only antennas from Cellwave (RFS now), DB Products, Sinclair, A/S, Telewave and a few other well known mfrs were used around here.

I've also been to some of our mountain top sites at 5000+ ft after a big winter storm and seen the massive debris of fiberglass splinters around all the towers due to the cheaper antennas breaking under heavy ice and wind conditions. I've never seen a damaged aluminum dipole array in these situations.

Unfortunately these high end antennas cost a lot but Telewave was a little cheaper than others at the time and we had excellent service from their 20 something ft long 10dBDUHF sticks.

At only 400ft elevation I would max out with a 20+ ft long fiberglass 10dBD stick (no downtilt) from a major mfr or my favorite, the DB Products DB-420 16 element dipole array. Unfortunately their expensive, but so is most anything associated with a commercial repeater.
prcguy

 

[fineshot1]

I am replacing my dipole array 4 bay antenna due to ice creating problems. I need a 7 or 8 db gain omni directional fiberglass replacement. I do have budget limitations and would like to get the most bang for my buck.

The Laird line is inexpensive and on paper sound good but I have heard of failures in windy situations. I have used Comtelco in the past but they do not make anything over 6db gain.

The site is 400 feet above sea level on a 6 story building. Wind has been an issue.

Any ideas?

Thanks

Mark

Ice can build up on any antenna and cause detuning problems during the iceing event until it melts.
Switching to another antenna design will not cure that.

I have had nothing but good experiences even during high wind periods with the 4 bay dipole arrays,
but they are not immune to ice build up either. The week point to the dipole arrays is the harness
which can fall prey to heat / cold expansion over time and exposure to the ultraviolet rays.

My preference would be to either replace the array or if a harness issue replace/fix the harness.

Or is there more to this issue than just an ice buildup problem?

 

[emtprt]

uhf antenna

This is a business repeater. DB 404. Our ERP is 60 but we are only around 20-25 per my calculations.

I have a second repeater with a DB413 antenna which bent due to recent winds.

The DB404 replacement with a 7 db gain antenna brings my ERP right where is should be. I did consider a Telewave dipole with spacing to provise some downward tilit to aid in covering an area 3/4 miles down hill. I feared the same issues that I had with the DB413.

When considering the ERP I looked at the outout post duplexer, jumper/cable loss, polyphasers insertion loss.

Ther repeater is a 40 watt gr1225 with 25 watts out at the duplexer, 118 feet of 5/8 hardline