Largest GMRS Base Station Antenna Avalible?

[badspell68]

I'm setting up an 50W Base Station, mounding antenna 15 to 20 feet on roof top. Are there large Base-Station antennas that can be roof mounted and what are the largest types for maximum transmission/reception?

 

Thanks all!

[tweiss3]

We are talking about 20' mast on top of 20' roof, not the Empire State Building, and not even a cell tower. Naaww, I do not believe 40' grounded mast changes charge field enough to truly attract lightning from the clouds. However, if lightning strikes in close proximity of said rod, the charge will likely to go through the rod, and not through the porch and your cat on that porch.

It's the OPs risk to take, but I have seen house hit that are less than 50' from trees towering 50' above their roof line. I would not be opposed to using metal to support the mast, but there is a bit more involved than buying 40' of fence post.

 

1) Evaluate your homes electrical system and current grounding situation.

2) Meet NEC at a minimum.

3) Look at finding a used tower for real structural support.

4) Review your insurance. I have my computer and every item in my shack insured. I don't want to be out those thousands of dollars when lightening hits.

5) Don't forget, you could fry everything electronic in your house with one good hit. How much in dollars are you TVs, computers and gaming consoles?

 

That being said, my HF antennas have the coax buried for 30', and I have a 70cm/2m antenna attached directly to my roof peak eave, but is grounded per NEC. Do I expect no issues? No, but I can hope to have no issues, and I can atleast say to an insurance adjuster that it met code if anything were to happen. Can you say the same?

[mbrun]

Just throwing it out. We have been using metal towers for antennas since nearly the beginning of radio. There are well established codes and best practices for lighting protection, grounding and bonding of said towers/masts. Follow the codes, and industry best practices and your risk is no greater or lesser than probably 99+ percent of all other responsibly installed towers.

 

Michael]

WRHS965

 

 

Sent from my iPad using Tapatalk

[axorlov]

All good points with regard to best practices and grounding per NEC. I'm not arguing with that. I'm saying that 40' mast grounded according NEC does not raise the chances of being hit by lightning. I'm also saying, that if hit by lightning, it's better to have a properly grounded mast than not to have one.

[mbrun]

Agreed.

 

All good points with regard to best practices and grounding per NEC. I'm not arguing with that. I'm saying that 40' mast grounded according NEC does not raise the chances of being hit by lightning. I'm also saying, that if hit by lightning, it's better to have a properly grounded mast than not to have one.

 

Sent from my iPad using Tapatalk

[marcspaz]

Dido...

[gman1971]

If you're really concerned about lighting then ground everything well, and then use tuned cavities. These cans (cavities) will provide excellent protection since the receiver will not be mechanically connected to the antenna. Also use a lighting arrestor at the bottom of the mast, grounded.

 

Its better to lose 1 dB in signal than to lose all your gear, and then, no signal at all.

 

G.

[rickh]

Running 1/2 of the DB 420B. Turned every other folded dipole 1/4 turn to make the antenna omni directional.

The full length 420 is kind of over kill for 50 watts with just a little DB gain. The one I am running is repurposed from commercial use and is dated 1979 and works great.

New they run about 1,500 bucks but due to the length expect another 200+ for shipping even broken in half. The last one I shipped was almost $400 UPS Ground cheapest way!

The 408 only specs out a few DB Gain less than the 420 and is about 1/2 the length and not quite 1/2 the price.

I would recommend contacting a local radio shop, especially a smaller one they may have some out of service UHF laying around, that's where I got mine, free for hauling them off, 6 of them!!! after tower removal. A lot of these antennas are still sticking up in the air off line as most business have gone to digital comms such as cell phones, YUK!

An economical alternative is the fiberglass vertical 

 

 

 

The DB420 Specs..

Product Description 450-470 Broadband N/Male Product Narrative 8-bay, dual exposed dipole. Field adjustable 9.2 dB omni/10.4 elliptical pattern. Also available in dual or quad version. Specific Freq. (MHz) 450-470 MHz Gain (dB) 9.2/10.4 Maximum Input Power (Watts) 250 IMPORTANT SHIPPING INFO Freight/Delivery Charges for this antenna is $195 Bandwidth >1.5 VSWR 20 Vert. Beamwidth (-3dB) 7 Deg. Lightning Prot. Direct Ground Direct Termination Jumper w/ N Male Overall Length 19.4' Support Pipe Dia. 2" Rated Wind Velocity (MPH) 100 MPH Wind Load, (sq ft) 3.33 Mount Hdw. Incl. DB365 clamps Weight 34 Lbs. Warranty 2 Years

 

 

The economy route, 

PCTEL/Maxrad - MFB4603-460-470 MHz 3dB Fiberglass Omni Antenna about 137 bucks guess where? AMAZON free shipping.

 

Rick H...