Help on Repeater ant to buy

Rich · Post by **Rich** » Fri Dec 19, 2003 2:24 pm

Here is a problem that I'm having with my Diamond X700.
Hopefully someone can give me some advice on which antenna would suit my needs best.

Problem:

My Diamond X700 cost me $400. I'm using it for a VHF repeater antenna.

The problem it causes is every now and then, I get gurgling noises and crackling in the transmit and it takes out weak signals.

This problem may stay in a few days and be gone for a few days and then come back again.

It is not my TX RX duplexer. That was already checked out.
I replaced my coax with LMR400. (75 ft. run)
I have even changed repeaters and get the same results.

Someone told me that the Diamond antennaes are NOT good in repeater service because they whip around and the rods inside do get broken and cause problems and will not show a bad SWR. My SWR is fine.

Anyone out here have the same problems that I'm having? Do you have any suggestions on a proper antenna to use?

I do have one suggestion and that was to get a Decibel products DB 224 antenna. Their website shows it as 6 DB gain where my Diamond is 9 DB.
I'm afraid that I will lose my receive coverage with the lesser DB gain.

Can anyone comment on the Decibel product? Any help and suggestions would be appreciated.

Or if you can suggest any other antenna that could be used for repeater use at my home.
ritchi50@optonline.net

ASTROMODAT · Post by **ASTROMODAT** » Fri Dec 19, 2003 2:36 pm

I would think this post should be under "Infrastructure."

Rich, I had the exact same problem with a Diamond antenna on a Ham repeater. Yes, they are cheap, but they are essentially a speedometer cable that is inside a fibeglass fishing pole. With lots of wind, they flop around and you have the sort of symptoms you have described. I also have had the experience of the Diamond antenna breaking off at its base in high winds.

IMHO, the "best" repeater antenna is the Cellwave Super Stationmaster (formerly Phelps-Dodge, then Cellwave, and now RFS). It is available in 2M and 440 MHz varieties (and you can get a 440-450 MHz range standard "out of the box"). It has 10 dB omni directional gain at UHF, with a half power point of about 6 degrees (relative to its bore site horizontal elevation). They are extremely rugged! They use a collinear sleeve dipole made out of thick copper tubing inside of a very rugged (and thick!) fiberglass radome.

Larry

Mike in CT · Post by **Mike in CT** » Fri Dec 19, 2003 3:52 pm

From my experience, only the big name antennas should be used for serious repeater service.

I dont really think you would notice a difference by "dropping" from 9dB to 6dB, depending on your actual coverage area, elevations, etc. Personally, I like using where possible 5 or 6dB antennas... the super gain antennas seem to be more of a problem here in Connecticut.
But if you are out in Ohio, or Kansas you might need that 12dB superflat pattern!

the LMR... I personally have reservations about using this type of line for repeater service, I use only hardline.

What did you use prior to installing the LMR? was it hardline or another run of LMR? was the problem existing then?

What comes to mind is a broken spot weld inside the antenna. (I THINK your antenna has spotwelds, someone correct me!).

Did you check all the connectors, plier tight rather than just finger tight?
Any corrosion? Loose connectors on any jumpers? (I hve found this to be a big problem)

does the problem change with temperature?

post some of the new findings, and we are all here with ideas (and opinions!)

Keep slugging on this problem, and we will too!

73,

Mike KM1R
in subtropical CT

Doug · Post by **Doug** » Fri Dec 19, 2003 4:04 pm

Hello Rich,
You may want to check out the topic LMR400/LMR600 under System Infrastructure. It may be possible that your antenna is not the total problem.
Doug

EKLB · Post by **EKLB** » Fri Dec 19, 2003 5:58 pm

Ill second the LMR400 coaxial cable as suspect.

Reason being i too had the above problems a few years back and swapped out the antenae with no luck in eliminating the sound i describe as eggs frying in grease.

As a last resort after checking duplexers/ transitter and reciever ect i finaly took the LMR400 coax down and replaced it with Andrew 1/2 inch hard line coax and what a diference.

The performance had improved beyond what i was hoping for.

In an attempt to find the reason the LMR400 was defective i found the coax to be dry as far as i could tell but after cutting the entire 125 foot length apart by removing the coating and internal shielding i found burnt spots through the shielding into the insulation material surounding the center wire.

Now i will say this= the repeater it was installed on was a high power unit at 75 watts output.

But i would have thought the coax should have handled this wattage.

Also the burnt through spots were in the first 10 foot of coax nearest the 75 watt transmitter and the balance looked good.

I had a 50 50 chance of starting at the bad end and could have used the balance of the coax but as i said it was a 50 50 chance and i started at the wrong end 50 50 chance? Yeah right not when it comes to my luck.

I really dont know why or whats as to the cause of the failure but i can say this.

I had the problem return about every two to three years and i replaced that same systems coax twice with LMR400 and the third time i went Andrew and its been up and running fine for aproximatelty seven years now without a problem other than normal routine maintenance.

I would consider trying a length of good coax and conect it to your system and see if it clears up the problem.

I would think you would be able to tell even at a lower heigth with your antenae say 10 feet of the ground taking into consideration you will be short on the mileage due to the lower antenae.

But if in fact you are having coax troubles it should clear up indicating your LMR400 is at fault.

IF the LMR400 is not at fault then id think youd still have the crackling noise your hearing now.

I would even consider backing down your tx power to say half and see what happens to the signals clarity.

Just a few ideas for you to ponder over.

EKLB

Post by **wavetar** » Fri Dec 19, 2003 6:15 pm

I am curious to see if you were using the LMR400 all along as well. The salesmen for the cable present a very good case for the cable, and I agree it's very good for certain applications. But, as far as external repeater use goes, you can't beat the Heliax cable for distances over 75-100ft, and I prefer RG-214 over LMR for distances under that.

As far as the antenna goes, Decibel/Celwave/Sinclair are the way to go for commercial use.

Todd

Susan157 · Post by **Susan157** » Sat Dec 20, 2003 9:04 am

We Only Use Sinclair Antennas For Long
Lasting Repeater Sites And Heliax Cable.

You Get What You Pay For.

The Ham Antennas Are A Super Price And We
Buy Them And Use Them On Field Day And For
Temporary Set-ups.

We Never Use Them For The Long Haul.
Over 64 Feet We Will Not Use Ham Antennas.
We Feel The Wind Gets The Best Of THem.

We Have Had Sinclair Antennas Working
That My Father Installed 20 Years Ago
That Are Still On The Air.

Will · Post by **Will** » Sat Dec 20, 2003 10:55 pm

I have to second Susan's choice of repeater antennae.

I prefer the folded dipole four bay VHF by Sinclair and Telewave, or the new Telewave fiberglass wide bander. Nothing like REAL copper elements in a heavy duty fiberglass radome.

RKG · Post by **RKG** » Sun Dec 21, 2003 9:25 am

When selecting any base station antenna, resist the temptation to purchase the highest gain available. Because of the narrow vertical pattern, such antennas can quickly overshoot your service territory (particularly in an in-cabinet installation).

Max-trac · Post by **Max-trac** » Sun Dec 21, 2003 9:39 am

Don't forget to look for ANYTHING loose or corroded on the tower!
(A crankup tower is a bad choice)
Any metal rubbing metal will create noise when excited with RF.
A rusty or corroded joint too.
This will change with the weather (moisture, wind etc) and RF levels.

Don't worry about gain figures, the Ham figures are inflated.

The Diamond may be fine until it falls apart.
I would suggest a 24' commercial antenna, can't get more gain than that unless you want to go directional......

Big Towers · Post by **Big Towers** » Wed Dec 24, 2003 10:08 pm

I have used both the DB-224 and the Phelps Station Masters. First I should point out that these were on repeaters in severe weather locations. I like both antennas, but if there is an edge, I would go with the DB-224s. You can get them cut within the ham band and they are a bit broder in freq coverage as well.

The tall Super Station Masters have a bit of wind bending that causes some signal changes in high wind (7500 feet, 40 MPH average) that the DB-224 doesn't have. Also, radial Ice on the station masters seem to cause more problems than on the 224, not to mention snapping in half or at the base.

You may not be in that type of environment, but to echo others, Ham antennas are made for the back yard on non-duplex stations, no matter what they say. And, as far as gain is concerned, a db-224 would be an improvement, no matter what number the ham manufacturer pulled out of his A$$. And at $400, no excuse for at least a DB-224. Station Masters are a bit more pricey!

I plan to install a DB-224 on a ham repeater on a mountain next spring. We tested with it and like the way it performed. As to cable, Heliax, I mean, heliax, or did I say, heliax! No other way to go, period, and the stuff is on Ebay all the time at prices less than RG-214, so once again, no excuse. Use the stuff with one of these two antennas and the only thing left is how good the repeater is and the duplexer.

ASTROMODAT · Post by **ASTROMODAT** » Wed Dec 24, 2003 10:43 pm

For some time now, the Cellwave (formerly Phelps/Dodge) Super Stationmasters have been available, off the shelf/standard, in the Ham bands. For instance, for the UHF Ham band, there is the Model PD-455-5, which is rated at 10 dBd for the 440 - 450 MHz Ham band (broad banded over the entire 10 MHz range). If you REALLY need heavy duty, you might want to go with the Cellwave Storm Chief. It handles 1000 watts, and can survive the worst storms and radial icing.

Larry

Susan157 · Post by **Susan157** » Wed Dec 24, 2003 10:56 pm

We Use 7/8 And 1-5/8 Heliax On Most 250-350
Foot Towers But You Did Not Talk About Hard
Line Cable.
Hard Line Is Used All The Time By
The Cable Company (75 Ohms) .

But 50 Ohm Hard Line Is Picking
Up In Sales Over Heli-ax Cable.
The Connectors Are Less Expense.
You Buy A Prep Tool And It Is Fast
And A Good Connection.

So The Great World Of Heliax Is Getting
Smaller Just Like "Ma M"

From A Heliax User In The Great White North
(Canada I Mean)

Seasons Greetings

Susan157

Big Towers · Post by **Big Towers** » Sun Dec 28, 2003 1:30 pm

ASTROMODAT wrote:For some time now, the Cellwave (formerly Phelps/Dodge) Super Stationmasters have been available, off the shelf/standard, in the Ham bands. For instance, for the UHF Ham band, there is the Model PD-455-5, which is rated at 10 dBd for the 440 - 450 MHz Ham band (broad banded over the entire 10 MHz range). If you REALLY need heavy duty, you might want to go with the Cellwave Storm Chief. It handles 1000 watts, and can survive the worst storms and radial icing.

Larry

Have used both and the "bending" issue seems to go away on the Storm Chief. Of course a whole new type of bending occurs when you wip out your check book for one

Now for the way back machine. Anybody remember when PHELPS gave a 40% discount on their products to ham radio clubs? Those were the days. I guess they started getting to broad-banded and somebody started hosing it up for the rest!

thehead7 · Post by **thehead7** » Fri Jan 02, 2004 2:24 am

I too have heard of problems with LMR400, but I can't remember the specifics. I also have experienced a lot of grounding related problems that create a lot of noise. Make sure you have a SINGLE ground system. When I was a kid I used a seperate ground rod for my HAM station. When I eventually got things figured out, I tied everything to a single ground (House electrical ground, telephone ground, a ground rod for my antenna, and a ground rod outside of my room). My mother didn't care for the ground wire running around the outside of the house, but my father understood the concept, haha... The difference was pretty surprising. I had less RFI on TX and RX... Your antenna can catch a lot of static. If that static is allowed to build up, it will eventually discharge. Electricity always takes the path of least resistance, so if you have a good ground system the effects of static buildup will be greatly reduced if not eliminated.

Of course, the ultimate ground system for a tower has a rediculous number of ground rods (probably about nine or so), with a radius of about 30 ft or so, and they are all tied together at the top and bottom... Haven't personally seen one yet, but it sounds like it would work. One day when I get around to moving out of an apartment, I'll build such a thing (with the assistance of an excavation crew, of course).

Also, make sure you have a ground strap running all the way up to the grounding point of your antenna. Installing a dc continuous polyphaser at the bottom of your tower will help reduce static issues if your antenna's radiating element is not DC continuous with ground...

Some of this may not have come out right because it's 0422 when I'm writing this, but you should get the idea.

Stay Motivated
-Head

Help on Repeater ant to buy

Help on Repeater ant to buy

repeater antenna

A Good Repeater Needs A Good Antenna.

7/8 and 1-5/8 standard Heliax cable But??