Brand new subdivision in Strathmore AB. Which is east of Calgary by about 40 Km.
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HF Vertical Multi-band
- Thread starter binrat
- Start date
I thought it was Alberta somewhere but i couldn't resist making the Saskatchewan comment when I saw that the nearest tree was at least 500 meters away. I suppose you are right however, in Saskatchewan the trees are a lot further apart than that. It makes for a real problem playing hide and seek to say nothing about how the dogs feel. 
as the element diameter is increased, if no other changes are made, then the element will become too "short" Vs. a thinner element @ the same freq.
even "tapered" antenna elements need to be longer than the normally computed dimension to become resonant.
My intent was to merely show that the electrical length changes as compared to physical length.
That being said, you got your electrical length change backwards. The fatter the antenna the longer the electrical length, not shorter. To compensate you have to shorten the physical length of the antenna if you want to maintain resonance.
The DB
HAHAHA, yes a lot further than 500 metres. I'd say in spots 10Km.I suppose you are right however, in Saskatchewan the trees are a lot further apart than that.
err, read it again,. that's what I said, (at least to the part of your last paragraph):"as the element diameter is increased,if no other changes are made, then the element will become too "short..."
to compensate, you need to lengthen the element if you want to maintain resonance.
if the elect wl is longer, why would you want to shorten the antenna to maintain resonance?
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If you increase the diameter of an antenna you have to shorten it slightly to maintain resonance. The change in diameter and length for resonance is in relation to those two things in reference to a wave length at the desired frequency. At HF, that increase in diameter has to get really large to make a slight difference in length. All that has been in the Hand Book's antenna section for a lot of years. It also contributes to an antenna's usable bandwidth to a -very- slight degree. Going from say a #18 wire to a #10 wire will not make any appreciable differences at all on HF. The required increase in diameter get's into the feet range, not fractions of an inch range before you ever hear or realize any differences.
Go look it up, see for yourself...
- 'Doc
Go look it up, see for yourself...
- 'Doc
Indeed. I saw almost no difference in length between my two 20m dipoles. One was 1/2 inch copper pipe and the other was 14 gauge wire. Any difference in length was VERY minimal. Now at 2m it made quite a difference as far as % of wavelength goes.
It depends on what part of the HF band you are referring to. Going from say 14 awg wire to a two inch diameter aluminum tube will have far more effect on 10 meters than it will on say 40 or 80 meters...
As I recall for a 10 meter half wavelength antenna a 1/2 inch diameter equates to something like a 5% shorter overall length to maintain resonance... Would have to look it up to confirm that number through...
The DB
As I recall for a 10 meter half wavelength antenna a 1/2 inch diameter equates to something like a 5% shorter overall length to maintain resonance... Would have to look it up to confirm that number through...
The DB
Interesting as I've been going through their site and found this DX Engineering MBVE-5-4UPR SAF-T-TILT
It's $10 cheaper and comes as a kit so it's cheaper for me in the long run.
It's $10 cheaper and comes as a kit so it's cheaper for me in the long run.
Frequency does make a BIG difference.
First time I ever played around with stacking a pair of two meter yagi's I was suprised at how just tightening a gamma match clamp will change the resonant frequency.
On the other hand on a 160 meter dipole a couple feet of wire can be cut off with out much change in resonance.
The problem with these 43 foot antennas is that on the higher frequency bands they produce lobes at high take off angles that are a lot stronger than the low take off angle which you want and some of the really sharp nulls are in those low take off angles <20 degrees.
My advice is to go for the tried and trusted Hustler 5BTV. No need for the expense of a tuner and you won't be panicking as much when its windy and it'll give better overall performance on the higher frequencies. 17m and 12m is easy to add for very little money with a bit of homebrewing.
My advice is to go for the tried and trusted Hustler 5BTV. No need for the expense of a tuner and you won't be panicking as much when its windy and it'll give better overall performance on the higher frequencies. 17m and 12m is easy to add for very little money with a bit of homebrewing.
You really should look into the Gap line of antennas. I have two, a Challenger and the 20 to 160 Meter model.
They require only 3 radials because they are a center fed vertical dipole. Because of that they are much quieter than bottom fed verticals. That has enabled me to make contacts I would have missed due to bad conditions or low power at the other end. I just run 100 watts and if I can hear them, I can make a good contact 97% of the time. I have great luck in getting through pile up's also, breaking at least 90% or more on average. It's the super rare stations with every big gun station after them that can be tough, but I've had some luck there too, all with 100 watts.
Every multi band vertical is a compromise, but the Gap's are fantastic. No traps or coils to go bad. They all stay within 2 to1 SWR at the most on every band, so no antenna tuner is needed, no losses, usual SWR is 1.3 to 1 to 1.7 to 1. They have a good low radiation angle and I have got some really great DX with mine.
Look at EHam.com for the reviews, the Challenger has two places it's reviewed, many pages of people very satisfied with them and just a few who were not.
I'd buy another if anything ever happened to mine. I've been told by more than a few they were very surprised I was on a vertical at 100 watts, they just plain work great and I love being able to change bands without touching anything but the band switch.
The model that covers 160 meters does about 130 Mhz, it's not going to be the best on 160, but it will be better than most any other multi band vertical I can think of and you can order different capacitors for different portions of the 160 band. 160 meters is the only band that has a capacitor or anything else on it and it's sealed in epoxy, but can be changed if you wish to. It allows decent 160 meter contacts even though it's limited there, some have made as many as 200 country's on 160, but I'd bet it took some work. It's 43' with a top hat that makes it look like it's 63'. It fantastic on 80 meters down to 20 meters. No add on's either, they come with all the bands I mentioned.
The Challenger does 2 meters, 10,12,15,20,40, 60 and a part of 80 meters. 20 and 40 meters are it's best bands, the Challenger's best is 20 and 40 meters. I live in a valley with mountains all around in rural Idaho, so no VHF gets in or out, so not much on 10 meters, but that's because of location more so than the antenna.
During the last good openings, I made one contact after another on 12 and 15 meters, only one to Africa, none to the Aussy's, but hit most other continents, Alaska, Hawaii and most states past 750 miles from me. The Gaps are much better at DX than my horizontal dipoles. They are better closer in.
If you get one or two, do use guy rope, mine have been through better than 70MPH winds with no problems at all.
I have nothing to do with Gap, just have been very surprised at the number of contacts made and pile up's broken into with just a Yaesu FT-450AT.
Do read the reviews and don't listen to the nay sayers unless they have had a Gap. People who have them seem to love them, people who know little about them tend to put them down. I have no doubt that with nothing to go bad, mine will be working 10-15 years down the road. They sit right on the ground also and come with the mounts needed, so no need to put it on a 20' pole to work.
They are not a yagi at 70 feet, but for a multi band vertical, they rock. My first contact was with Switzerland.
73's John KF7VXA
They require only 3 radials because they are a center fed vertical dipole. Because of that they are much quieter than bottom fed verticals. That has enabled me to make contacts I would have missed due to bad conditions or low power at the other end. I just run 100 watts and if I can hear them, I can make a good contact 97% of the time. I have great luck in getting through pile up's also, breaking at least 90% or more on average. It's the super rare stations with every big gun station after them that can be tough, but I've had some luck there too, all with 100 watts.
Every multi band vertical is a compromise, but the Gap's are fantastic. No traps or coils to go bad. They all stay within 2 to1 SWR at the most on every band, so no antenna tuner is needed, no losses, usual SWR is 1.3 to 1 to 1.7 to 1. They have a good low radiation angle and I have got some really great DX with mine.
Look at EHam.com for the reviews, the Challenger has two places it's reviewed, many pages of people very satisfied with them and just a few who were not.
I'd buy another if anything ever happened to mine. I've been told by more than a few they were very surprised I was on a vertical at 100 watts, they just plain work great and I love being able to change bands without touching anything but the band switch.
The model that covers 160 meters does about 130 Mhz, it's not going to be the best on 160, but it will be better than most any other multi band vertical I can think of and you can order different capacitors for different portions of the 160 band. 160 meters is the only band that has a capacitor or anything else on it and it's sealed in epoxy, but can be changed if you wish to. It allows decent 160 meter contacts even though it's limited there, some have made as many as 200 country's on 160, but I'd bet it took some work. It's 43' with a top hat that makes it look like it's 63'. It fantastic on 80 meters down to 20 meters. No add on's either, they come with all the bands I mentioned.
The Challenger does 2 meters, 10,12,15,20,40, 60 and a part of 80 meters. 20 and 40 meters are it's best bands, the Challenger's best is 20 and 40 meters. I live in a valley with mountains all around in rural Idaho, so no VHF gets in or out, so not much on 10 meters, but that's because of location more so than the antenna.
During the last good openings, I made one contact after another on 12 and 15 meters, only one to Africa, none to the Aussy's, but hit most other continents, Alaska, Hawaii and most states past 750 miles from me. The Gaps are much better at DX than my horizontal dipoles. They are better closer in.
If you get one or two, do use guy rope, mine have been through better than 70MPH winds with no problems at all.
I have nothing to do with Gap, just have been very surprised at the number of contacts made and pile up's broken into with just a Yaesu FT-450AT.
Do read the reviews and don't listen to the nay sayers unless they have had a Gap. People who have them seem to love them, people who know little about them tend to put them down. I have no doubt that with nothing to go bad, mine will be working 10-15 years down the road. They sit right on the ground also and come with the mounts needed, so no need to put it on a 20' pole to work.
They are not a yagi at 70 feet, but for a multi band vertical, they rock. My first contact was with Switzerland.
73's John KF7VXA
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