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Author Topic: Looking for a 2m/70cm Vertical Base Antenna  (Read 4631 times)
KK4CRY
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Posts: 35




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« on: April 16, 2013, 08:45:16 PM »

As title states looking for a 2m/70cm vertical base antenna, would love it to be all aluminum(metal). Havent had any luck with previous antenna made of fiberglass domes ex Hustler G7-144. Ive been comtemplating using a Slim Jim (Two Way Electronix), Ed Fong base antenna
But recently the Force 12 Ruby-270s has caught my interest. For me its all about performance, im currently running a Arrow OSJ 146/440 and not impressed.

Can some one give me some direction?

Tkx
Ben
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KQ6Q
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Posts: 991




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« Reply #1 on: April 16, 2013, 09:17:39 PM »

If the Arrow J isn't doing the job for you, then you need to look at other factors - how high is it ? can it see the horizon? In what directions ? What kind of coax are you feeding it with ? how long is the coax ? What kind of radio are you using? How far are the repeaters you're trying to hit ? Can you hear them clearly ? Have you tried simplex with a local ham ?
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KK4CRY
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Posts: 35




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« Reply #2 on: April 16, 2013, 09:45:55 PM »

I did the comparison on simplex to a station 15miles away as the crow flies. Radio is a IC-V8000 on high power, antenna is at 32ft at the connection point of the coax, coax is 50ft of rg8x, antenna is surrounded and amongst oak trees, We compared the arrow to a Hustler G7-144.
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WB6BYU
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« Reply #3 on: April 16, 2013, 09:52:46 PM »

I'd start by looking at the gain required to meet your operating needs.

A J-pole is just a vertical dipole, and a "Slim-JIM" is just a J-pole made
more complicated than necessary.  They will (at best) work as well as any
other antenna with a radiator roughly 3' long, including ground planes.

To get better performance in an omnidirectional antenna you need to make
it taller, or (better yet) get it up higher in the air.

I've had great luck with the AEA IsoPole on 2m.  It isn't designed  for dual-band
operation, though it will hit the local repeaters.  This is a 2 x 5/8 wave antenna,
pretty much the same as any other type that has an 8' tall radiator.  (The actual
antenna is taller due to the decoupling cone on the bottom.)

Overall, radiator length is probably the easiest comparator for antenna gain, at
least on 2m.  Antennas that are about the same length (ignoring matching stubs
like on the J-pole and decoupling systems on the IsoPole and Ringo Ranger) will
give about the same performance (unless they are built particularly poorly.) How
such an antenna is adapted to also cover 440 will vary, and some types will have
different performance trade-offs between the two bands.

One other factor that is particularly important with J-poles and derivatives is how
well the coax is decoupled from the antenna.  Common mode current on the coax
can distort the radiation pattern and make it much worst than necessary, and
many J-pole designs are especially bad in that regard.  In some cases just changing
the length and/or routing of your coax can make a significant difference.  (We put
up a J-pole on the roof of a school once, and had it insulate it from the vent pipe
it was mounted on to be able to hit the local repeater.)
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KL3HY
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Posts: 120




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« Reply #4 on: April 17, 2013, 08:32:25 AM »

I have to ask--what problems did you have with your fiberglass radome Hustler that turned you off to them?

I've been extremely happy with the performance of my Diamond X300, and it's just a basic fiberglass radome vertical.  It's survived two 100+ mph wind storms, and many 50-70 mph storms, so durability doesn't seem to be any problem.

Mike
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KL3HY
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Posts: 120




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« Reply #5 on: April 17, 2013, 10:04:35 AM »

coax is 50ft of rg8x

I missed this--50 ft of RG8x is going to be very lossy, especially on 70cm.  I'd start by replacing that with LMR-400.  Regardless of what antenna you replace your Hustler with, you're still going to have that feedline loss.

Mike
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W8JX
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Posts: 6468




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« Reply #6 on: April 17, 2013, 11:33:12 AM »

coax is 50ft of rg8x

I missed this--50 ft of RG8x is going to be very lossy, especially on 70cm.  I'd start by replacing that with LMR-400.  Regardless of what antenna you replace your Hustler with, you're still going to have that feedline loss.

Mike

I always love this, 50 feet of RG8x looses about 4 db on 440 which is not a big problem for repeater work and antenna gain can easily make up for this. When comparing RG 213 the loss will be about 2.4db and with LMR400 about about 1.4db. Point is there is only a difference of 2.5 db between 8x and LMR400 on this run  which is not a big deal here. If run was longer then a better cable is warranted.  On 2 meters the losses are about 1/2 this and difference between cables far less. I am not say that LMR400 or its like is not warranted in some applications but rather it is over played for need at times.
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K2OWK
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Posts: 1073




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« Reply #7 on: April 17, 2013, 11:35:30 AM »

I have the Arrow GP146/440. It is Fed with about 30 feet of RG8X coax. I am using an old Yaesu FT-4700RH (50 watts VHF/45Watts UHF). It is up about 15 feet, and I can reach all repeaters some up to 30 miles away. This antenna is a 1/4 wave ground plane on VHF and a J-Pole on UHF. There is a good test on it in the Feb.2013 QST (page 61). I bought it because I needed an antenna with a small footprint that was reasonably efficient and I was not disappointed. It is very well made reasonably priced at under $40.00. I have it mounted on a piece of 10 foot schedule 80 PVC pipe. The complete unit is very light and so far has withstood high winds with no failures. As far as loss in the RG8X it is 1.8db at 50 feet at 150 MHZ, and is 3.15 db at 450 MHZ. The 400 would be about half of that. At these frequency's height is more important then coax loss. The higher the better. I am very happy with my set up.

Just my opinion,

73s

K2OWK
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KL3HY
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Posts: 120




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« Reply #8 on: April 17, 2013, 12:07:32 PM »


I always love this, 50 feet of RG8x looses about 4 db on 440 which is not a big problem for repeater work and antenna gain can easily make up for this. When comparing RG 213 the loss will be about 2.4db and with LMR400 about about 1.4db. Point is there is only a difference of 2.5 db between 8x and LMR400 on this run  which is not a big deal here. If run was longer then a better cable is warranted.  On 2 meters the losses are about 1/2 this and difference between cables far less. I am not say that LMR400 or its like is not warranted in some applications but rather it is over played for need at times.

I understand what you're saying, but he said he's all about performance.  He's also said he's not happy with the performance of a vertical dipole at 32 ft, which should be more than adequate for "repeater work".  So clearly he's interested in more than something that's simply adequate for hitting nearby repeaters.  That tells me that RG 8x losses might be relevant.  So while I'm sure you've seen it mentioned too often, please don't jump down my throat.

Mike
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W8JX
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Posts: 6468




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« Reply #9 on: April 17, 2013, 12:17:54 PM »


I always love this, 50 feet of RG8x looses about 4 db on 440 which is not a big problem for repeater work and antenna gain can easily make up for this. When comparing RG 213 the loss will be about 2.4db and with LMR400 about about 1.4db. Point is there is only a difference of 2.5 db between 8x and LMR400 on this run  which is not a big deal here. If run was longer then a better cable is warranted.  On 2 meters the losses are about 1/2 this and difference between cables far less. I am not say that LMR400 or its like is not warranted in some applications but rather it is over played for need at times.

I understand what you're saying, but he said he's all about performance.  He's also said he's not happy with the performance of a vertical dipole at 32 ft, which should be more than adequate for "repeater work".  So clearly he's interested in more than something that's simply adequate for hitting nearby repeaters.  That tells me that RG 8x losses might be relevant.  So while I'm sure you've seen it mentioned too often, please don't jump down my throat.

Mike

A vertical dipole is a very minimal antenna for 2m or 440. If he put up a antenna in the Diamond X200 or X300 class he will see a noticeable difference even with 8x. I have a 2m Hustler G7 that is about 45 feet at base and has about 85 feet on RG213 feeding it. Never really found it lacking. Been up there for close to 20 years now.
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KK4CRY
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Posts: 35




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« Reply #10 on: April 17, 2013, 12:30:53 PM »

I do more local simplex then repeater, the Hustler G7-144 did great in simplex and repeater work, but it doesnt have 70cm, and im not a fan of weathered fiberglass.  
The arrow didnt perform very well on simplex, but i can still hit the local repeaters and is all metal.

The current antennas im looking are the Force 12 Ruby-270s, Hustler G6-270R, couple different Diamond Dual band models, or even making a Copper Cactus
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N6AJR
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« Reply #11 on: April 17, 2013, 12:37:40 PM »

put up a decent vert for fm repeater work, then get a 2m/440  beam ( there are several dual band  3 or 5 element beams available cheep) and use these on a small rotor for point to point use.  most folks who do distance work on 2m / 440 mhz they use either ssb or cw. but the beams work good on fm too.
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KL3HY
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Posts: 120




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« Reply #12 on: April 17, 2013, 01:22:05 PM »

I do more local simplex then repeater, the Hustler G7-144 did great in simplex and repeater work, but it doesnt have 70cm, and im not a fan of weathered fiberglass.  
The arrow didnt perform very well on simplex, but i can still hit the local repeaters and is all metal.

The current antennas im looking are the Force 12 Ruby-270s, Hustler G6-270R, couple different Diamond Dual band models, or even making a Copper Cactus

Ahh--okay.  If you were happy with the performance of the Hustler on 2m then I'd say you'd be happy with something like the Diamond X300 for both 2m/70cm, or the bigger version, the X510.  For longevity of the fiberglass I've heard of people spraying various paints on it, and as long as it's not a metallic paint that should help some.  I haven't done that myself though.

If you want gain without fiberglass, you could always go with a DB-224E and the 70cm version and switch between the two.   Wink

Mike
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N4CR
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Posts: 1694




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« Reply #13 on: April 17, 2013, 01:58:20 PM »

If you're a simplex operator there is no substitute for height.

http://www.qsl.net/w4sat/horizon.htm

VHF/UHF Line of Sight Calculator

32' Antenna Height of 1st Station (your station)
6' Antenna Height of 2nd Station  (a vehicle)
  
For the 1st station, the Radio Horizon is 8 Miles away.
For the 2nd station, the Radio Horizon is 3 Miles away.
The total line of sight distance is  11 Miles.

Assuming the earth is spherical and there are no obstacles, this is a best case scenario. There is no way to fix this with an antenna or gain or power.

I'll take a VHF/UHF antenna at 10 times the height with 1/10th the gain any day.
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73 de N4CR, Phil

Never believe an atom. They make up everything.
KK4CRY
Member

Posts: 35




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« Reply #14 on: April 17, 2013, 02:14:56 PM »

Wish the War Dept. would allow me to stuff an antenna in one of these oak trees, you should hear my dilemmas for HF antennas.
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