How long is too long ?

[TX1C]

I have a BC796D. I live out the country, wide open field in the back of my house. I'm wanting to put a Discone out there on some kind of mast or tall wood pole. Most of the antennas I'm seeing have 50 ft cables. I would need about 100ft (or maybe 150ft) to get back to my house. Would I lose alot of signal with that long of a run ?

Thanks for any advice !

Christopher
Dripping Springs TX

 

[cj5]

A discone can work really well inside, better probably outside. I have my BC796D connected to a discone antenna clamped to a DJ speaker stand that extends about 8' up on my outside 2nd story landing, with about 20' of coax, and the signal is phenomenal. I'm pretty sure that the longer the length the weaker the signal gets, I'm not sure, but with the antenna out in the field away from household and surrounding EMI, the reception would be super clear. Why not just set it up nearer to the house?

 

[TX1C]

House blocks out everything...

I thought about in the house, in the attic, near the house etc.... I thought the wide open sky would be great for reception. Also, the main reasons are that I have a Tin roof and a stucco house that has a layer of wire mesh surrounding the whole thing. I'm guessing a 100-150ft will be ok. Thanks for the thoughts !

 

[cj5]

Same here, I have a tin roof also, and being in a fairly rustic area, one would expect very little action on the scanner, but I can't shut the thing up. It's fairly busy with air, public safety, forest and land, and ham action. I should try putting the stand outside to see what the difference is. As far as the length goes, I don't think that it would really be a significant drop in reception if you do decide to go out to the field. I would think the tin roof would have more of an effect on your reception than the length of your antenna wire.

 

[N_Jay]

Don't worry about getting away from the house, just get above it.

Use the SHORTEST piece of the BEST cable you can afford to get as HIGH as possible.

 

[K5MAR]

Use the SHORTEST piece of the BEST cable you can afford to get as HIGH as possible.

That statement ought to be a sticky!

Mark S.

 

[LarrySC]

Anything gained by geting in the clear is lost in the long coax run. Remember the rule KISS.

 

[mgosdin]

That statement ought to be a sticky!

Mark S.

Agreed, I ran a short ( 20' ) run of 1/2" Heliax cable up to a RS 20-176 antenna. This duplicated my existing RS 20-176 that uses RG8x and the difference is like night & day. The RS 20-176 / Heliax combo pulls in Railroad signals from a roughly similiar area as the RS 20-176 / RG8x pairing, but previously weak signals are much clearer and I'm hearing both sides of conversations with the Heliax where I only hear one side with the RG8x.

It cost a few dollars to make the change, that and the time it took to take the mast down and put it back up. A minor investment for a significant improvement.

Mark Gosdin

 

[Al42]

I have a BC796D. I live out the country, wide open field in the back of my house. I'm wanting to put a Discone out there on some kind of mast or tall wood pole. Most of the antennas I'm seeing have 50 ft cables. I would need about 100ft (or maybe 150ft) to get back to my house. Would I lose alot of signal with that long of a run ?

This site will give you loss per length for various cable types for various frequencies. 3db loss is half the signal (6db is 3/4, 10db is 90%). You can run 100 or 150 feet of cable with not much loss if you're willing to pay for the right kind of cable, or if you're only listening to lower frequencies. But don't try a 150 foot run of RG6 if you want to monitor anything in the 850 MHz band - it'll give you 12.8db loss - just about all the signal. Or RG58 - 21db, or a little over 99% loss. LMR600 is reasonable - 3.6db loss, or just a little over half the signal. But 150 feet of it isn't cheap.

Do as N_Jay says - just get the antenna over your house - and keep the cable as short as possible.

 

[JackTV]

Try LMR 400 cable it is very low loss cable from 30-1300 mhz.It is not that expensive and it is a heck of alot better then RG-6.If you order LMR400 try to get the exact connectors you will need to hook up to your antenna and radio. (it might be a pl 259,type N male or BNC) Also the less the amount of connectors the more you hear. Also like eveyone else said get the antenna as high as possible. good luck


Jack

 

[Al42]

Also the less the amount of connectors the more you hear.

Someone posted results of an actual test on BNC->SMA adapters on one of the yahoo groups a while back. The adapters probably have some loss, but whatever it is, it's less than the 0.1db (IIRC) he was able to measure.