Discone height

[Lockedin]

Hi all, first post. Been reading for a while.
Recently back to listening. Still have Uniden bearcat 800 XLT and a uniden mobile? 800 something..haven't used those for 30 years, power cords and antennas missing.
Prior to those I remember riding my bike to radio shack and buying crystals. LOL. Memories.

I recently put up a D130J and wow, it works like I had hoped. Scanner is a home Patrol 2. Was good with rubber ant. but now is great.
Peak of home is about 25' and I have 8' of mast so antenna is about 35' now. With my 2 piece Adjustable eve mount, how much more mast could I safely use? Getting good reception now but you know how it is..
I'm thinking another section or two can't hurt!
I don't see a lot written about antenna height when it comes to scanners. Is it worth going another 10' or is it sort of a moot point,? I.E: very little gain.
Located in CT BTW.
THANKS !

 

[ka3aaa]

the higher the better

 

[Lockedin]

Thank you Sir.

 

[bb911]

Don't forget the Law of Diminishing Returns. May not be worth it.

 

[KC4RAF]

Both KA3AAA and BB911 are correct. High gets great signals, but then you have the loss in the coax and connectors. Just set with what you have at 35 feet. You can go higher if you wish but try not to use any more barrel connects, etc. In other words, use just one coax without connectors.
If you're happy with what you are receiving, let it be.
And welcome to RR; It is a great site for any type of radios, transceivers and what nots...

 

[Lockedin]

10-4 and thanks for the replys guys.
You sort of read my mind in that I have a little extra coax in the one 75' legenth. Had about a 60' run so with my 75' LMR400 coax I guess it makes sense to go another 10' since the extra is just coiled in the basement anyway. Rodger on no more connectors, understood, makes sense.
Just hoping the bracket will support it. Seems rock steady, like I could hang off it. Another 10 should make munch difference.

 

[bobsav21]

Discone

Hi all, first post. Been reading for a while.
Recently back to listening. Still have Uniden bearcat 800 XLT and a uniden mobile? 800 something..haven't used those for 30 years, power cords and antennas missing.
Prior to those I remember riding my bike to radio shack and buying crystals. LOL. Memories.

I recently put up a D130J and wow, it works like I had hoped. Scanner is a home Patrol 2. Was good with rubber ant. but now is great.
Peak of home is about 25' and I have 8' of mast so antenna is about 35' now. With my 2 piece Adjustable eve mount, how much more mast could I safely use? Getting good reception now but you know how it is..
I'm thinking another section or two can't hurt!
I don't see a lot written about antenna height when it comes to scanners. Is it worth going another 10' or is it sort of a moot point,? I.E: very little gain.
Located in CT BTW.
THANKS !

I too recently installed a D130J and despite all the discone haters out there I found that it works great for me.
I have mine mounted in the attic at the present time. I your case since it's outdoors already I don't think another 5-10 feet will gain you very much. I think I might gain some more by moving it outdoors but if your happy with the reception your getting I would leave it alone, and as the previous poster said if you do move it dont add any connectors that you dont need.
JMHO
Bob

 

[jonwienke]

The greatest benefit of height is achieved once you get the antenna above all nearby terrain, trees, and buildings. Increasing height beyond that adds some benefit, but not nearly as much.

 

[Lockedin]

Rgr that. Surrounded by 80' plus oaks I will never really get completely above everythIng. I wondering if it's worth it as the reception is so good now.
The D130J seems to be working really really well.

 

[mmckenna]

With my 2 piece Adjustable eve mount, how much more mast could I safely use? Getting good reception now but you know how it is..
I'm thinking another section or two can't hurt!

Since I don't see any of the previous replies addressing this, I'll reply…


How high you can go is really based on a number of factors. Yes, the cable being able to reach the antenna is one of them, but you really need to consider these, too:
1. What is the mount rated for when installed per directions and with specified hardware?
2. What is the condition of what it's mounted to? Is it wood? Does that wood have any dry rot, checking, cracking, etc? Will the mounting screws/bolts hold, or will they pull out when the wind blows?
3. Wind loading is something you'll hear if you read much on this subject. Wind load is how much force a certain wind speed will exert on the antenna, mast, cable, hardware, etc. As you go up in height, the wind load increases and it'll put a lot of strain on the mount. Discones are not svelt antennas, they have a lot of wind drag, so to speak. Add in LMR-400, and that increases wind load.
4. The mast material. If you are using TV antenna mast, it's usually in 5 or 10 foot lengths. You can stack it, but the joints will need support. Much above 10 feet and you'll need to add guy wires for support, or the whole thing will just fold over. The thin metal won't support much force.
5. adding to #1 above, is it secured with lag bolts? Through bolted? Or sheet rock screws? (seriously, had an installer try to do this at one of our sites once…)
6. Probably 20 other things I'm omitting….

Without knowing a lot about your setup, I wouldn't go any higher than you are now, unless you plan on adding guy wires, using heavier mast material, and making sure your mounts are very well secured. A falling antenna can do a lot of damage on it's way down.

If it's working satisfactorily now, I'd not waste the time/effort/money trying to get a few more feet out of it. While these frequencies do work primarily by "line of sight", adding a few more feet probably isn't going to make a noticeable difference.

 

[iMONITOR]

the higher the better

For performance to some degree, but not for safety, which was the OP's original question. A 2 piece adjustable eve mount is not suitable for very much wind load.

Then there's this thing called lightning!

 

[Lockedin]

Since I don't see any of the previous replies addressing this, I'll reply…


How high you can go is really based on a number of factors. Yes, the cable being able to reach the antenna is one of them, but you really need to consider these, too:
1. What is the mount rated for when installed per directions and with specified hardware?
2. What is the condition of what it's mounted to? Is it wood? Does that wood have any dry rot, checking, cracking, etc? Will the mounting screws/bolts hold, or will they pull out when the wind blows?
3. Wind loading is something you'll hear if you read much on this subject. Wind load is how much force a certain wind speed will exert on the antenna, mast, cable, hardware, etc. As you go up in height, the wind load increases and it'll put a lot of strain on the mount. Discones are not svelt antennas, they have a lot of wind drag, so to speak. Add in LMR-400, and that increases wind load.
4. The mast material. If you are using TV antenna mast, it's usually in 5 or 10 foot lengths. You can stack it, but the joints will need support. Much above 10 feet and you'll need to add guy wires for support, or the whole thing will just fold over. The thin metal won't support much force.
5. adding to #1 above, is it secured with lag bolts? Through bolted? Or sheet rock screws? (seriously, had an installer try to do this at one of our sites once…)
6. Probably 20 other things I'm omitting….

Without knowing a lot about your setup, I wouldn't go any higher than you are now, unless you plan on adding guy wires, using heavier mast material, and making sure your mounts are very well secured. A falling antenna can do a lot of damage on it's way down.

If it's working satisfactorily now, I'd not waste the time/effort/money trying to get a few more feet out of it. While these frequencies do work primarily by "line of sight", adding a few more feet probably isn't going to make a noticeable difference.

Thank you for the great response. I was indeed wondering the ability of the bracket.
I didn't notice a rating for it anywhere although how high it is rated for would depend in part on the antenna your running I'd imagine.
I am in sound wood and used washers under the lag bolt heads to spread the bolt torque across the bracket more.
I am also using swedged antenna mast, 18 gauge. I believe it is a lot heavier that normal TV antenna mast.
Right now it is solid. No worries but I'm not sure about adding another 8' unless I can get an arm type bracket to go mid mast down to roof. That's where it gets to be more $ and time than maybe it's worth.
I am also toying with a CB base antenna and maybe getting into SSB or other armature radio. That will add a whole new antenna, problem to consider.
I truly appreciate your precise response to my original question.

 

[Lockedin]

For performance to some degree, but not for safety, which was the OP's original question. A 2 piece adjustable eve mount is not suitable for very much wind load.

Then there's this thing called lightning!

Ouch. That musta been painfull to look at.
Yes, I can see where the 2 piece, although solid is all at the bottom and not offering any support mid range.
I do have a lightening kit with 3-3' spikes I plan to install tomorrow to hopefully prevent my house from looking like that.
Thanks for the great reply!

 

[Lockedin]

We got hammered with that rain / wind storm 2 days ago and had power out for 24 Hrs. Some people still don't have it back. Winds were gusting about fifty MPH. Trees and poles down all over, still have some roads blocked. I went out mid storm and although it was blowing pretty hard, the antenna was not moving. It looked very stable. Probably best not to push it at this point.

 

[jhooten]

the higher the better

Limited by the losses in the feed line.

 

[iMONITOR]

Ouch. That musta been painfull to look at.
Yes, I can see where the 2 piece, although solid is all at the bottom and not offering any support mid range.
I do have a lightening kit with 3-3' spikes I plan to install tomorrow to hopefully prevent my house from looking like that.
Thanks for the great reply!

Well, it wasn't my house thank God! But I saw something in person several years ago. It made me think about mounting an antenna very high on my home.

Keep in mind, lightning rods, grounding antenna masts, etc, do not prevent your home from being hit. And if it does get hit, they're might help minimize damage, but not eliminate it. They all work toward neutralizing and dissipating the lightning charge build up so that hopefully it doesn't strike to begin with.

Check with professionals, but as I recall, code required a ground rod to be 6-8 feet long.

I think you'll probably be just fine with your current setup, and it's 8' mast. But if it were me, I wouldn't go any higher.

 

[spongella]

The higher up my antennas are, the more worried I get in bad weather hi hi. Especially ice storms, thunders storms, hurricanes, Nor'easters, etc.