Im needing a good antenna to mount on top of a 20 foot tower that is should also do 440.
I was looking at the Diamond X700HNA
Much feedback welcome because I am new to ham.
Also I plain on running 150 to 300 watts depending on the antenna and amp.
How much are you willing to spend? #For around $100, you can get a Tram 1481 that will give you a claimed 8.3dBi of gain on 2M and 11.7dBi of gain on 70cm. #But, you could spend more, or less, and still get a decent dual band antenna. #So, how much do you want to spend?
Hands down best? Think "more than $100." Think Stationmaster by Celwave.
I will spend more than $100 but I dont think that more than $500 wont have any benifits but that is why Im here asking
If all you've got to spend on your 2M/70cm vertical base antenna is $100, the Tram 1481 IS the "hands down best." #
Originally Posted by [b
I'm really not an expert, but I will tell you to check the power ratings on the Diamond. I used to run a 200 watt amplifier on occasion on FM, to work some very distant machines. 200 watts to a vertical is usually a very bad idea, anyway - you will bring up every repeater on that channel pair for hundreds of miles when the band conditions are right. But nonetheless, I managed to 'fry' my Diamond slightly. It's rated at 100 W and it means it. I am not sure what the rating is for the antenna you mentioned.
For the kind of money you're talking about, consider a small beam and a TV antenna rotator to turn it on top of a 25 foot TV mast. 50 watts into a 10 dB gain yagi yields an ERP of 500 watts, and it will greatly help your receiving, too, by making the distant station seem 10 X as strong. Cushcraft has two dual-band yagis. The bigger of the two gives you 5 elements on each band for $129. AES sells a light duty rotor for $69. You'll want some good coax to feed it with - LMR-400 (DON'T USE CHEAP COAX! 83/92 cents a foot + connectors.
For working distant stations, this will beat the heck out of a vertical.
EchoLink, IRLP, Allstar and DSTAR linking - adding interest to repeaters worldwide 24X7
It occurs to me to mention to you that, while a good antenna is important, height above average terrain is even more so, when it comes to 2M and 70cm.
Originally Posted by [b
Given a choice between a 20 foot tower with a 24 foot antenna, like the Diamond X700HNA mounted on top of it, and a 45 foot tower with a homemade 1/4 wave ground plane mounted on top of it, I would choose the 45 foot tower with the homemade 1/4 wave ground plane. #Why? #Because, the 45 foot tower with the smaller antenna will have the primary radiation lobe higher above the ground than the primary radiation lobe of the bigger antenna at the lower height.
I recently built a one 1/4 wave element over eight 1/2 wave elements collinear vertical for the 1.25M band out of 8 gauge copper wire (about 19 feet tall). #For testing purposes, I used some rope to pull the antenna up into one of the pine trees in my back yard. #I got the feedpoint of the antenna up to about 50 feet above the ground. #The antenna had an initial SWR of 1.3:1 at the design frequency of 223.520; so, I didn't have to make any adjustments.
Now, I had been using a 5/8 wave ground plane for 1.25M pulled up into the same tree; but, because the antenna was considerably shorter, I was able to get the feedpoint up another 15 feet, or so, higher above the ground than I could get the feedpoint of the collinear above the ground.
The application for this antenna is in a 1.25M to 2M crossband repeater setup. #I use it while mobile to talk with my buddies who are too far away for me to work from my vehicles. #And, I have had a few months experience with the shorter antenna and know where many of the weak and strong spots are in the area.
What was interesting to discover was that the smaller antenna performed significantly better than the much higher gain (about 9dB over 1/4 wave) collinear antenna I just built. #But, of course, its primary radiation lobe was located higher above the ground.
Now, had I been able to get the feedpoint of the collinear antenna up to the same height as the smaller antenna, I have no doubt that the collinear would simply blow the little 5/8 wave ground plane away in terms of performance.
So, my point is that your money and/or efforts would be better spent in acquiring a higher support for your antenna than to get a better antenna.
Of course, having said that, I must also say that even this rule isn't hard and fast. #For example, if your 20 foot tower is already 5500 feet above the surrounding terrain on top of a mountain, an extra 25 feet isn't going to provide as much benefit as a bigger, higher gain antenna with a better pattern would provide.
The main thing is to get the antenna as high and in the clear as possible. #If you can do that easier with a smaller antenna pulled up into a tree, you might save yourself some money and get better coverage at the same time.
Im moving into a house that alread has a 20 foot tower that I would have thought to be used for TV. I would like to make the best of it with a great antenna and not install a new tower. Just trying to make the best with what I aready have to work with.
I like the idea on a dual-band yagis. this could also keep me from having to buy a amp.. Good point guys. Now Im probably heading in the right direction
The Diamond X700HNA or Comet GP-9 will work quite nicely for a home VHF/UHF FM station.
Remember - for VHF/UHF work, the antenna's height above average terrain (HAAT) and your coax choice will make the most difference in your station's performance - not antenna gain, or transmitter power. In other words - a high-gain antenna won't make up for a poor location and/or a long run of lossy coax. Neither will an amplifier. A rule of thumb I use is to keep my system losses below 1 dB if possible - main coax & jumpers included. Of course, if one has no choice as to location, a high-gain antenna in a poor location is still better than a low-gain antenna in a poor location. But never, ever skimp on coax for VHF/UHF/SHF work.
With this above in mind - I suggest using 1/2" hardline (not SuperFlex) or Times-Microwave LMR-600 for your main coax run, if you can afford to. At bare minimum, use LMR-400. At VHF and especially UHF, coax losses can easily ruin the performance of an otherwise great station. Also, don't use an SO-239 to N adapter to connect to the antenna's N connector, rather, terminate your coax with an N connector on the antenna end.
Don't forget to have a good VHF/UHF SWR/Power meter connected to your station - especially if you run an amplifier.
Hope this helps - and good luck with your station! If you have more questions, I will be happy to help, if I can.
Joel - N0NCO
"The mind is like a parachute. It doesn't work unless it's open." - Frank Zappa
Claimed. Just out of curiosity... Has anyone been able to confirm these numbers with their own tests? Sounds like a decent antenna, at least on paper...
Originally Posted by [b
[I]"...and the greatest of men would be silly and lazy,[/I]
[LEFT][I]so I would be king, if the world was crazy"[/I][/LEFT]
[LEFT]--- Shel Silverstein[/LEFT]