Batboard

I had a quick question, mabye some one could help. I am going to put up another site "qucik and cheap" I have a tkr-750 that has been lying around and I am going to put it up for I guess for a back up or voter site. I already have a vhf system on a 527' tower. I have some property that I hunt on and nextel contacted me to see if i was intrested in letting the build a tower/lease the land to put it on, of course I was willing if they would let me put my vhf system on it. The tower is 699 foot, its there multi distrubition point, for our area, But any way I have a 200' foot tower about 40 miles away and was going to put the tkr-750 on it. I have about 150' of andrew 7/8 helaix left over from a previous job, Instead of buying a new roll of coax if I added 50' of andrew ldf4 1/2 with n connectors how much loss would I looses in that connection and reduction of coax size? If and body could answer my question I would greatly appricate it. Thanks in advance. Josh

According the coax calculator I use...

150' of 7/8" loss @ 155Mhz: 0.685db
50' of 1/2" loss @ 155Mhz: 0.415db

Looks to me like about 1db of cable loss which is pretty damn good. As far as connectors, that I can't help you with but i can't imagine it being significant.

You won't have a loss issue.

My main concern would be with waterproofing... the more connectors, the more potential for water to get into the coax. Obviously, a Bad Thing. Make sure you properly waterproof the point where the two cables come together.

Of course, the Andrew-approved solution would be to get another piece of identical 7/8" and use a splice kit with its waterproofing to make the connection.

Your biggest concern should be the tension of the lower cable pulling on the upper cable at the connector. In just about every use I have seen of a cable splice or 2 connectors being used, after some time the lower cable always pulled enough to break the connection.

I have seen all sorts of cable hangers (chinese finger type cable hanger) used to relieve the cable tension from the lower cable. So far, I have seen all attemps at this being done fail. You could provide some cable slack at the splice point that should prevent this problem. Just don't rely on the cable splice ot support the weight of the lower cable by itself.

Jim

tvsjr wrote:You won't have a loss issue.

My main concern would be with waterproofing... the more connectors, the more potential for water to get into the coax. Obviously, a Bad Thing. Make sure you properly waterproof the point where the two cables come together.

Of course, the Andrew-approved solution would be to get another piece of identical 7/8" and use a splice kit with its waterproofing to make the connection.

thanks for all the replies I really appricate it! I have some well about 15 andrew 7/8 coax hangers mabye they will work. what would you reccomend? thanks, Josh