Input on repeater crackeling

[Pump3]

Hey guys
I recently installed a community repeater, a Vertex-Standard VXD-R70 Repeater (XPR8400 Clone), CSI TP-154 Plus Controller, Sinclair Q2220E Duplexer with a extra Sinclair Bandpass Cavity on the Rx leg, and a Sinclair SD222 Antenna fed with LDF4-50 and a chunk of RG-214....

Now i've searched the boards and read every article I could find and I havent been able to figure this out, it seems to be most noticable on the repeaters hangtime, there doesnt seem to be anything loose on the rack and the UHF repeater above it sounds 100%, i've kicked the rack and wiggled everything inside and can't seem to find the cause, SWR on the antenna is around 1.15.....sometimes its more noticeable, sometimes you can't hear it, but more so then not you can....weather seems to have no effect on it....

Suggestions? Ideas?

Since its most noticeable on the hangtime when its not in duplex i'm more inclined to think the issue is in the coax or antenna

[Bill_G]

Do a desense test.

[Jim202]

Try doing a search on the LMR coax cable.

There have been many threads on the use of LMR coax cable being used for duples (repeater) service. It seems that the difference between the foil shield and the braided copper shield seem to cause all sorts of intermod problems that you will never resolve. The older the cable the worse the scratchies will be. All the comments I have seen point to moisture getting into the area between the two materials. Any flex in the cable just makes the problem show up even more like days with high wind.

Those that have gone before you have given up and just replaced the LMR coax with some form of a heliax type cable.

You have been pointed in the direction to do some homework. The decision on which way to go in trying to resolve your problem will come down to doing some preliminary testing. As Bill G has suggested, do a sesitivity test to see just how bad the problem is. You can then pull the antenna cable off the duplexer and put a good dummy load on and do the sensitivity test again.

Jim

Hey guys
I recently installed a community repeater, a Vertex-Standard VXD-R70 Repeater (XPR8400 Clone), CSI TP-154 Plus Controller, Sinclair Q2220E Duplexer with a extra Sinclair Bandpass Cavity on the Rx leg, and a Sinclair SD222 Antenna fed with LDF4-50 and a chunk of RG-214....

Now i've searched the boards and read every article I could find and I havent been able to figure this out, it seems to be most noticable on the repeaters hangtime, there doesnt seem to be anything loose on the rack and the UHF repeater above it sounds 100%, i've kicked the rack and wiggled everything inside and can't seem to find the cause, SWR on the antenna is around 1.15.....sometimes its more noticeable, sometimes you can't hear it, but more so then not you can....weather seems to have no effect on it....

Suggestions? Ideas?

Since its most noticeable on the hangtime when its not in duplex i'm more inclined to think the issue is in the coax or antenna

[Pump3]

Thanks for the input,
Theres no LMR crap in the set up at all, I stay clear of that stuff, its a run of good RG-214 through the building, (a lot of tight turns) and Andrews LDF4-50 Heliax from the attic to the antenna...

I'll run some desense tests, I only wish Motorola put a local speaker in the trbo repeaters, isn't like theres a lack of room....

[Doug]

Sounds like your in for a treat...I've seen where loose mounting hardware (tower bolts flange bolts etc) generate noises

[Pump3]

Its on a roof of a hotel, wood/shingles....so there isn't too much metal stuff to have to go kick

[N4DES]

Is it actually reducing the unit's talk-in capability or is it only on the hang-time?

My UHF repeater will occassionally make, I guess the best I can call it, a low carrier beat like if it was a simulcast it would sound like a simulcast growl.
It doesn't affect the in-bound audio at all and it isn't there all the time. I just ignore it.

[Pump3]

I would like to know what it is just for my own curiosity sake, it doesnt seem to affect in bound audio so far, so if I can't find out what it is i probably will take your advice and shorten the hang time to a half second or something

[N4DES]

You just might find that it is more dependent on your location and it isn't local to the repeater. That is what I have found, but YMMV.

[wavetar]

Have you tried removing the controller from the equation & running straight through the repeater? Perhaps there is a shielding issue with it's wiring or similar?