What he said.  A beam will always show more gain since it has director and reflector elements to control the direction of radiation.  Height above ground is also important with a beam, not so important with a vertical.  Verticals can be ground-mounted and work very well.


Also, there is no "a" in "Dipole".  It's simply "Di" as in two and "Pole" as in polarity or legs; two legs of the antenna, each a quarter wavelength long.

Thanks
I'm only gonna have about 20ft so Dipole?

What band? 20 feet isn't a resonant length for any amateur band.

I'm wanting 20meter how high will that have to be?

Sorry I misunderstood thought you meant length. 20 feet isn't as high as I'd like for 20 meters but if that's all you have it will work, although a vertical will do better for DX if you have room to install one.

So you got a FT-991A from HRO in the last couple weeks?    I have been watching them looking for one myself, I'm camping within a stones throw of the Portland store just waiting.  That is not the primary purpose of my trip to Oregon but it is on my list of things to do.  

On your old FT-840 they are a decent rig but they are getting old there is no doubt.   Is the low power output on all bands and modes or just one area?   On older rigs bandpass filter relays can become problematic but you should see different performance on different bands.  Another issue with Yaesu radios of that vintage are crappy solder joints and they can start giving you trouble even in an aged rig.   It is rumored that in that time frame Yaesu had some contractors building various components which weren't quite up to snuff.  On that rig I would pay particular attention to the IF filter section and see if manipulating components, wires, connectors and etc. bring a change in performance.   And with the aid of a service manual, block diagrams and schematic diagrams you can trace your TX signal all the way from the microphone to the antenna jack using all of your senses as you inspect each stage, most diagnostic procedures don't require fancy test equipment and often you can simply remelt solder joints and bring a dead circuit back to life.   I have never had any formal "radio tech" training yet I have managed to successfully diagnose and repair all of the problems which have cropped up in any of my gear so far.

Like most things to do with antennas height will always be a tradeoff, and higher is always better.  From the PDF File at This URL published by the ARRL and entitled "Antenna Height and  Communications Effectiveness, Second Edition":

A beam type of antenna at a height of 70 feet or more will provide greatly superior performance over the same antenna at 35 feet, all other factors being equal. A height of 120 feet or even higher will provide even more advantages for long-distance communications. To a distant receiving station, a transmitting antenna at 120 feet will provide the effect of approximately 8 to 10 times more transmitting power than the same antenna at 35 feet.


A tower that tall will require guy wires.  Do you have room for them?  In addition, safety factors come into play.  If a 120' tall tower with a large beam antenna falls in ANY direction, what is it going to hit?  You have to be aware of that because you will be held responsible if it happens.  And of course there is the question of cost.  A 120' tower, base, guy wires, antenna, rotator, feedline, etc. are not cheap by any means.

I used to have an 80' tower with a 2-element cubicle quad on top.  I would have liked to have it higher but that was all I  could do so I lived with it and it worked extremely well.

I met another Han at the Free Flea Ham meet to day who says he can fix the ft840
And Is very familiar with them. So I'll take it to him when the TF991A gets here. He acted like he knew what it was.

The HOA will not let me have that 80ft tower. Maybe 30ft at the most.

That's pretty low but I had a friend with a 2-element yagi on a 30' tower and he made it work pretty well.  Same problem as you, I think, in that a HOA stopped anything taller.  The good thing is that if you put enough concrete for a base and use the proper tower and you can do 30' without guy wires with just about any antenna.

You know those vintage three-legged TV antenna towers that you probably climbed on as a kid? They were already standing all over town when I was born in the late 60's, and I still see a hundred a day if I look for them. In my area, they're all 50 feet with those big TV antennas still on them. I'm pretty sure those non-tapered style towers are supposed to be guyed at that height, but I have never seen a single one that was. Maybe it's a regional thing. I do know that they swayed enough to scare me as a kid, and I wouldn't climb one today even on a bet. I'm looking for one, and when I find it, I'll have a buddy take it down and put it back up.

Yeah, I remember them.  A lot of them were "Repurposed" as ham antennas at some point to, and most probably fell over ;)

We had to show a 40' tower at a pump station site once and I got the base design info from Rohn's web site.  As I recall, and it's been a few years, Rohn 25G can be free-standing (no guy wires) up to 40' with the proper base.  The base size varied with the soil type and antenna wind load but around here with a VHF monopole antenna it was a 6' x 6' x 6' block over (I think) 12" of crushed stone.  That's a big chunk of concrete and I suspect most 4' towers don't have that much.

Is it just me or is there seem to be an uptick in ham? It seems the Ham Radio sales
are up and my radio is backorder to 6/2 now.And others are sold out. Also my Dipole is out of stock too.

bump

My Radio and Dipole came yesterday.
Wow that's a lotta Knobs.

No kidding! The nicer radios these days have so many features it is incredible. I got my station up and running over the weekend, and now I am working on how to use the radio. That is going to take me quite a bit of time. It is fun, though, so I hope you enjoy the process with yours, too.

Did you wind up with a FT-991A? I really like mine. Seriously, take a couple of hours and read through the manual and try each function and adjustment out to get acquainted. I can give you some tips for basic "getting on the air" settings.