* new listening post ideas *

[twolf816]

were adding onto our house, so i gotta move my rs antenna; since were getting our roof done as well, i cant have anything mounted on the actual roof; so i was thinking about just getting a new antenna, chimmney mount, 10ft mast, and a multicoupler. my questions are as follows: is 10ft of mast a good height? whats a good antenna for 25mhz to 800band (i mean i want the same quality in the 800 band as the vhf band)? and lastly, if i get a 4port multi coupler for 2-3 scanners (2 during the day, 3 at night) does it matter of all the ports arnt being used? i think thast about it, thx in advance

 

[N_Jay]

were adding onto our house, so i gotta move my rs antenna; since were getting our roof done as well, i cant have anything mounted on the actual roof; so i was thinking about just getting a new antenna, chimmney mount, 10ft mast, and a multicoupler. my questions are as follows: is 10ft of mast a good height? whats a good antenna for 25mhz to 800band (i mean i want the same quality in the 800 band as the vhf band)? and lastly, if i get a 4port multi coupler for 2-3 scanners (2 during the day, 3 at night) does it matter of all the ports arnt being used? i think thast about it, thx in advance

1) Are you happy with teh antenna you have?

If so, use teh same antenna at atleast the same height

2) Are you using the multicoupler today?

If not, be ready for 7dB of loss.

There are no scanner antennas that will get you back the 7dB.

 

[twolf816]

1) no; its ok i guess but it dosnt pickup 800mhz even though its "108-1200mhz.

2) no ive never owned a multi coupler. every one ive seen advertises "....with no loss". so whats up with that? and will it matter if all 4 ports arnt being used?

 

[Al42]

were adding onto our house, so i gotta move my rs antenna; since were getting our roof done as well, i cant have anything mounted on the actual roof; so i was thinking about just getting a new antenna, chimmney mount

You don't want to mount an antenna over a chimney - the stuff coming out (sulphuric acid is just one component) will rot the antenna a lot more quickly than if it were mounted upwind of the chimney.

10ft mast

Above the ground? Above a 6 story house? In a deep valley? On the highest hill in the area?

There's no way to tell if "a 10 foot mast" will do what you need. If you can see for miles from your mounting point a 6 inch mast is enough.

if i get a 4port multi coupler for 2-3 scanners (2 during the day, 3 at night) does it matter of all the ports arnt being used?

Yes - a multicoupler has to have all ports terminated - by a receiver or by a resistor. Radio Shack sells terminating resistors. They're 75 ohms, they're on F connectors, but they're non-reactive, which is what you need. Just get an F-to-whatever adapter and plug it into whatever port doesn't have a receiver connected to it.

every one ive seen advertises "....with no loss". so whats up with that?

No loss. If you pour a gallon of water equally into 4 containers you'll get a quart in each container. No loss. What you won't get is a gallon of water in each container.

In the same way, if you have a 1 watt signal (just to have some numbers to work with - you don't want to pump a watt of RF into a scanner's antenna connecter) and split it into 4 receivers, each receiver will get 1/4 watt - a 6 db "loss". None of the signal is "lost", though, but that's why there are amplified splitters - so that you get a gallon in each container - the amplifier adds the "missing" 3 quarts.

N_Jay answered the rest of your questions, but let me make a suggestion:

Talk to the roofing people. They can mount a tripod (the Radio Shack 15-517 or equivalent should be enough for a scanner antenna) on the peak of the roof while they're doing the roof - in a way that will guarantee no leaks for as long as the tripod lasts, which will only be 5-10 years. Then you just drop your mast into the tripod.

 

[twolf816]

i live in a flat area mostly, but half of my scanning deals with monitoring 30-40 miles away; and i talked to a manufacterer of a chimmney mount, they said that its no worse then having an antenna on your roof, actually better because the temp wont reach 150deg+ like it does in the summer. and since i happen to not live in my own house, the tripod idea is out the window; with the multicoupler, the one im looking at is amplified as opposed to just a splitter; so im thinking im gonna go that route.

 

[safetyobc]

ward8vfd, You can always try different mounting options other than on the chimney or roof. Here are some to check out:

Dish Wall Mount with antenna mast

Eave Mount

RS Attic Mount

RS Eaves Mount

RS Universal Mast Mount

 

[Al42]

i talked to a manufacterer of a chimmney mount, they said that its no worse then having an antenna on your roof, actually better because the temp wont reach 150deg+ like it does in the summer.

You expected to hear something like "Well, our product is really no good, but we'd like you to use it anyway"?

Check out some of the alternatives safetyobc gave you.

since i happen to not live in my own house, the tripod idea is out the window

Your landlord would rather you put a strain on the chimney it was never designed for, rather than let his roofing people install a tripod correctly? You need to do a little "social engineering" and "landlord education".

 

[twolf816]

thx safetyobc, ill keep that in mind.

You expected to hear something like "Well, our product is really no good, but we'd like you to use it anyway"?

well no offense, id much rather listen to an employee of the company whose been my friend for years than someone ive never met before.



i was asking more about recommended antennas and the multi-coupler hence thats what im worried most about as there are many types of base antennas and except for portable and mobile antennas, i have only owned 1.

 

[MacombMonitor]

A Vent Pipe mount might be an option! As long as your antenna is not too big, or heavy. I'd probably go with a 5ft mast, to reduce stress. These mounts clamp to the sewer vent pipe on the roof. If it's old construction, the pipe will be made of iron. If it's new construction, it will be white PVC plastic. Either is strong enough. But if it's plastic, do not over tighten it. Here is a link for one that Radio Shack sells:

http://tinyurl.com/cnmbg

As for using an amplified multicoupler, keep in mind, any amplifier that is at the radio end of the coax, is going to amplify all the stray noise the cable picks up, in addition to the signal you're trying to receive. Antenna amplifiers work best when mounted at the base of the antenna, on the roof. That way you're just amplifing the signal, and pushing it down the coax.

 

[twolf816]

nice!!! thx, i might go that route. whats the best antenna for 25-1200mhz (and i want to hear 800mhz cause the one i got now says 108-1200mhz but its not) that i can install this way?

 

[MacombMonitor]

You didn't actually say what antenna you're using now. It may be that your antenna is fine. Your inability to receive the 800MHz band may be to poor coax, or corroded connectors. These can be fixed, and you may be able to use your existing antenna. If you do need a new antenna, there are several to choose from. Some better than others, but at a cost. How much can you afford to spend? Also, how long will your coax need to be?

 

[twolf816]

this is the antenna i have now - http://www.radioshack.com/product.a...me=CTLG_008_009_010_001&product_id=20-176

it never has picked up 800mhz from the get-go, it didnt matter at the time cause i didnt have a scanner that was 800mhz capable. i want to get a new antenna. something that has equal vhf reception as 800mhz reception. i would like to look at several before i have price boundrys. as to how much cable i need, it depends on my mounting option.

 

[kb2vxa]

Hi Ward and all,

"...i talked to a manufacterer of a chimmney mount, they said that its no worse then having an antenna on your roof, actually better because the temp wont reach 150deg+ like it does in the summer."

I hate to be the bearer of such news but your "friend" has more loyalty to his company than he has to you. Stop and think a moment, the antenna will be above the roof no matter how you mount it, the only thing that will get hot is the coax if you lay it along the roof. Spacing it but an inch or two will raise it off the hot shingles and allow cooling air around it. I once did a bit of a skywire arrangement from a chimney mount to an attic vent to avoid heat damage to the coax.

BTW, I agree that a chimney mount isn't such a good idea since if the house or apartment has oil heat the antenna will get covered with soot and corroded by sulfurous gasses. (I have taken down TV antennas that crumbled in my blackened hands.) Gas heat produces mostly water vapor which can get inside things and cause condensation in cool weather, you don't want a waterlogged antenna and/or coax. Then too you don't want to pay a mason to repair damage to the chimney caused by your installation. (Even if your antenna isn't the cause the landlord will blame you if something happens, people are like that.) I saw a brand new "heavy duty industrial strength" chimney crack for some still unknown reason after a very light, low wind resistance scanner antenna was mounted on it.

Speaking from experience after carefully considering all the possibilities including keeping the landlord off your neck I also suggest the vent pipe mount and short (5' TV style) mast. I have gone higher like 10' with a 10' antenna atop it and found the brackets twisted when I took it down, live and learn. You won't gain much with a few extra feet of elevation, keep it low and avoid stressing the brackets, the landlord, and yourself when you catch hell.

For what it's worth my tri-band vertical and 6M dipole are on a 15' mast bracketed to the railing of the uppermost fire escape landing. Like the man said, I socially engineered my landlord by demonstrating it's stability with a good shake that made him happy. It's been up through 5 years of our famous winter gales and he's still happy.

Last but not least, do a bit of social engineering with the roofers too. Once upon a time there was a big TV antenna atop the building I worked in feeding the tech shop and one day it stopped working. I went on the roof to investigate and found the roofers had poured hot tar all over the coax melting and burying it at the same time. They buried the pipe it entered the building through so in order to replace the coax I had to dig it out damaging the roof. Then we called them back to fix it and I wasn't too pleased having to spend a very hot afternoon on the roof riding herd on them like I should have in the first place when the season was still cool, again you live and learn.

 

[twolf816]

:roll: ok first of all; my friend has told me and other customers to go else where for some products because they suck, not because hes my friend, but because its the right thing to do, so i dont need your input on that subject. also, i decided on the vent pipe option so now i need to see what antennas i can put up there

 

[Declared_Hostile]

ward8vfd you asked me about multicouplers in the other tread:

Just from my experience I have had zero luck with T fittings, cable TV splitters, amplified cable TV splitters and the like. The scanners interfered with each other and the signal loss was a problem among other things. I bit the bullet and went with the active stridsberg multicouplers. They work great for me. No more interference problems, no detectable signal loss and they have performed flawlessly. They've been on more or less continuously for a few years now. No scientific measurements just judging by ear and signal strength and the lack of interference problems. No complaints. Very happy with the products. They ain't cheap however. Well worth it to me though.

I've got 2 of the active 8 port VHF/UHF models and 1 of the active 8 port HF models.

I asked stridsberg about using terminators and he told me to use them if I had them but don't worry about it if I didn't.

 

[Al42]

this is the antenna i have now - http://www.radioshack.com/product.a...me=CTLG_008_009_010_001&product_id=20-176

it never has picked up 800mhz from the get-go

It looks like it has elements for lo-VHF and hi-VHF, so that's not surprising.

i want to get a new antenna. something that has equal vhf reception as 800mhz reception.

A discone receives from design frequency to ~3-4 times that frequency well, and still fair above that. Design frequency is the frequency at which the length of the cone is 1/4 wave, so you'd want one that has a cone approximately 18" long for 150. Parallel elements work also - like the ground plane antenna you have, or as dipoles. You'd want at least one element (2 for a dipole) 18" long (for 150) and at least 1 3 " long (for 800).

Actually a parallel dipole hung vertically would do the job pretty well, if you hung it on some radio-inactive PVC pipe. (Put a small piece of the pipe in a microwave - with a cup of water to protect the microwave - and nuke it for about a minute. The PVC should stay cool.) You can use 1 element for each band you want to receive, so you can cover more than any commercially-available scanner antenna. If you use something around #6 wire the bandwidth shouldn't be too bad.