Home 2m Base Antenna

[prcguy]

The NJ is a Japanese version with the frequency ranges centered on their FM bands. You would want the HDN version.

What is the difference between the X510HDN & the X510NJ?

 

[tibadoex]

The NJ is a Japanese version with the frequency ranges centered on their FM bands. You would want the HDN version.

That's exactly what I needed to know - thanks!

 

[tibadoex]

Any input on a decent SWR meter for a 2m / 70 cm antenna? Or some to stay away from. Something not too complicated to operate.

 

[prcguy]

I would go with an antenna analyzer, you don't need to transmit and they will give you a lot more information about the antenna. Avoid MFJ but there are a lot of good cheap ones out there that will test everything you will ever own.

Any input on a decent SWR meter for a 2m / 70 cm antenna? Or some to stay away from. Something not too complicated to operate.

 

[bill4long]

What is the difference between the X510HDN & the X510NJ?

NJ are optimized for the lower part of the 2m and 440 bands for Amateur TV (UHF), SSB phone and CW (VHF.)
For FM phone simplex and repeaters, get the H series. They also handle more TX power.

 

[bill4long]

The NJ is a Japanese version with the frequency ranges centered on their FM bands. You would want the HDN version.

That too. Turns out they are more optimized for people working ATV, satellite (UHF) and SSB 2m.

 

[tibadoex]

Question on antenna grounding. I think I know the answer but I will ask anyway. I am putting but both a 2m/70cm base and a CB base on one end of the house. Antennas will be 14' apart. (Monitoring both simultaneously, but only transmitting on one at a time.)

1. Can they share a GND rod? By putting one in the middle so it's 7' from GND to pole on each?
2. What gauge wire should I use to run from antenna to GND rod?
3. Best to attach wire from antenna bracket bolt down to GND or bottom of pole to GND?

I'm going to guess it's safer to use a GND rod for each antenna.

 

[mmckenna]

Question on antenna grounding. I think I know the answer but I will ask anyway. I am putting but both a 2m/70cm base and a CB base on one end of the house. Antennas will be 14' apart. (Monitoring both simultaneously, but only transmitting on one at a time.)

1. Can they share a GND rod? By putting one in the middle so it's 7' from GND to pole on each?

Yes.

2. What gauge wire should I use to run from antenna to GND rod?

10 gauge minimum, and sufficient for a 7 foot run. If the run was longer, you would want to increase the size.

3. Best to attach wire from antenna bracket bolt down to GND or bottom of pole to GND?

Grounding the mast as long as it's metal, is fine.

I'm going to guess it's safer to use a GND rod for each antenna.

Would not hurt, but not necessary.
Your antenna ground rod must be bonded to the house electrical ground rod. Any additional ground rods you add all need to be bonded together.
There's a lot of details, though, that are not easy to cover here. Ground resistance may require more than one ground rod to properly ground things, but that's veering off into commercial grade installs.

You also need to have a grounding block/lightning suppression device on the coaxial cable at the point it enters the home. That block/suppressor needs to be bonded to the ground rod, also.

 

[WA8ZTZ]

When it comes to ground rods, generally, more is better. Just make sure that they are all bonded together and to the building grounding electrode system with 6 AWG copper. Too much detail to cover completely here, see NEC Articles 250 and 810 for more complete coverage.
Also, ARRL Grounding and Bonding for the Radio Amateur by Silver is an excellent reference.

 

[bill4long]

Grounding is good for many things but not to mitigate a direct lightning hit. Ever. In fact, it can make your outcome worse.
Disconnect your coax during lightning storms. You may not be able to do that for a repeater. Regardless of your situation, be insured.
Direct hits will be total destruction to any equipment directly connected to the outside, and very bad for ground potentials.
Be insured. Unless your rich. Be insured. And unplug the coax if you can.

 

[prcguy]

I disagree that a general statement of grounding is bad for a direct lightning hit. In fact in a properly designed lightning proof system it is one of the key components. Most of the mountain top repeater sites I use has had many direct hits over the years, destroying antennas but with no damage to coax, the building, the repeater or any other electronic device in or attached to the building. These buildings and their electrical systems were designed from the ground up for lightning protection and they work every time.

You can't survive a direct hit at home without taking it all apart and putting it back together the same way these repeater sites are built.

Grounding is good for many things but not to mitigate a direct lightning hit. Ever. In fact, it can make your outcome worse.
Disconnect your coax during lightning storms. You may not be able to do that for a repeater. Regardless of your situation, be insured.
Direct hits will be total destruction to any equipment directly connected to the outside, and very bad for ground potentials.
Be insured. Unless your rich. Be insured. And unplug the coax if you can.

 

[TailGator911]

I have used the same 2m base antenna since 1995 - Comet AR-270B vertical. Now and then I might take a suggestion and try a different antenna, but I've not found one to compete with it. Love my Comet!

 

[AK9R]

Comet AR-270B? I think you mean Cushcraft AR-270B. Cushcraft Amateur Radio Antennas

 

[bill4long]

I disagree that a general statement of grounding is bad for a direct lightning hit.

You're dead-ass wrong. Sorry. Average lightning strike is 300,000,000,000 coulombs of electrons. Think of that as 300 billion watts in a very short time, if you need a mental anchor. Nothing survives a direct hit. Total destruction. Commercial radio/TV stiations spent lots of money to mitigate some damage. But ham radio situations? You simply don't know what the hell you're talking about.

 

[prcguy]

"You simply don't know what the hell you're talking about" My, that's kind of harsh since you don't know me or what I do....

I always preach its basically impossible to protect your home antennas from a direct lightning hit, probably never gonna happen But for commercial radio/repeater/satellite installations many survive directs hits all the time with no damage except for the antenna itself. They are designed specifically for that with massive grounding systems.

The buildings I service repeaters in for others and that I have had my commercial repeaters in have survived many direct hits with only the antenna being blown up. I've replaced a number of antennas but none of the equipment or infrastructure was damaged. I've worked in many of the major 5,000ft mountain top repeaters in So Cal like Mt Wilson, Mt Lukens, Santiago Peak, Seirra Peak, Box Springs, smaller ones like Palos Verdes and in Santa Barbra, Gibraltar Peak and Broadcast Peak plus Cheyenne Mt above NORAD in Colorado Springs at 11,500ft, Clarke Mountain at the CA/NV border and bunch of others I forget.

You might not have a clue about these sites (the So Cali guys and girls will) but I've done mountain top repeater and tower work for the last 40+ yrs and have seen a bunch of lightning damage. I was also responsible for design and installation of many multi million $$ satellite uplink systems that require the very best practice grounding techniques to protect the huge $$ investment. None have ever failed due to lightning strikes.

Here is a pic of me several years ago climbing up to inspect a US Coast Guard antenna that was blown to bits by a direct hit, but the repeater and everything else in the building was humming along just fine. This was the second antenna blown up in just a couple of years on this repeater and we replaced the Station Master with a Sinclair dipole array and no problems so far. It may have been hit again but its working fine.

Just because you or your friends sites have not survived a direct hit doesn't mean its not possible because it is and I've seen and experienced it. What's your story Bill?

You're dead-ass wrong. Sorry. Average lightning strike is 300,000,000,000 coulombs of electrons. Think of that as 300 billion watts in a very short time, if you need a mental anchor. Nothing survives a direct hit. Total destruction. Commercial radio/TV stiations spent lots of money to mitigate some damage. But ham radio situations? You simply don't know what the hell you're talking about.

 

[bill4long]

I always preach its basically impossible to protect your home antennas from a direct lightning hit

So essentially we agree. The rest of your post was irrelevant posturing given that we're talking about ham radio antennas, as clearly stated. Alrighty then.

 

[WA8ZTZ]

Not all lightning bolts are created equal so it is hard to say how much (or little) damage a direct hit will do.
However, proper grounding and bonding is intended to mitigate the damage. Otherwise cell companies, electric utilities, TV and
radio stations and the like would not spend tons of money burying tons of copper and tying everything together with more tons
of copper. At the very least, the radio amateur, SWL, CBer, etc. should follow the rules in the National Electrical Code (NEC).
The NEC is a 120+ year culmination of the best thinking regarding practical electrical safeguarding. See especially Articles 250 and 810.
The NEC is not intended to be an instruction manual for the untrained. One needs to know how to apply the Code rules. The ARRL book referenced in my post #49 above is a good place to start. Concern here is not just for the radio gear but (and maybe even more importantly)for the structure and occupants as well. Grounding and bonding are really quite straight forward but there is a lot of bad information out
there by self-styled "experts". Stick with trusted resources and qualified professional help.

 

[stingray327]

Comet GP 1, 3 and up. Self tuning. No need to adjust SWR.

 

[JoshuaHufford]

Comet GP 1, 3 and up. Self tuning. No need to adjust SWR.

How does the antenna tune itself?

 

[bill4long]

How does the antenna tune itself?

It's broad-banded enough to cover 2/440 with 1.5 SWR or less. Fuggedaboudit.