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.


Go with the DB Products or any other comercial 4 bay dipole antenna. The
ones like Comet and Diamond are fine for some home applications . They
just will not stand up to being mounted on a tall windy repeater tower.
Hate to say it about a product but you bought expensive junk...

The antennna must be getting its gain numbers over a rubber duckey at ground
level. There is no way to get 9 db of gain with an antenna about 20 feet
long (omnidirectioal) . The 4 bay dipole antenna will give just under 6 db
over a dipole if it is correctly made. Colinear antennas will give even
less for that length .
Something around 5 dbd is more like it.

Check out the repeater builders group on Yahoo for information. Don't take
my word for it , I have only been keeping a repeater up for a little over 25
years.
Go he

http://www.kuggie.com/rbtip/

and click on the repeater builders technical info page.

BTW they do not think much of the lmr400 due to problems like you seem to be
having. The braid and the foil reportably flex in the wind and make that
kind of noise in a duplexed system. I am running a repeater that for the
last 2 years that has 100 feet of lmr400 on it and I am not noticing the
noise. It may take a rew years to develop as the brade loosens up . I don't
really know. I do know that if you have loose guy wires or other loose
hardware on the tower you will get the noise in the receiver when the
transmitter is on. I did have a guy wire problem one time . Tower is 100
feet of Rohn 25G With a stationmaster on top . The top guy wires on the
ground anchor had about 3 feet of loose ends. When the wind whipped the
ends back on the guy wire going to the top of the tower I had noise like
mad.

De KU4PT