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Author Topic: 6M Yagi-ht above ground - performance  (Read 4513 times)
W3HKK
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« on: March 02, 2011, 05:15:00 PM »

How low can you go and still work  effective Es? 

Last May I bought a 5 el yagi and put it up 6 ft off the patio. Running 100w I worked 37 states and 4 countries including EU.  Worked the entire west coast beaming THRU the house during May-Jul. 

Now that was fairly effective but I could tell it wasnt keeping up with the average bear.

So Im curious how others with   5 el yagid and 100w do with low antenna hts like 10-15-20-25 ft or so?
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N6ORB
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« Reply #1 on: March 02, 2011, 07:28:36 PM »

I have 333 grids confirmed since 2006 using 100W and a portable Moxon at 13 feet. All contacts were SSB. Best DX so far is Puerto Rico.

Yes, I'm in an HOA, so no permanent antennas.

Five elements seems like cheating.  Smiley

To put things in perspective, one of the locals here in the Bay area confirmed 325 grids last summer. Also, I believe it was a guy in Alabama who worked 325 grids during the VHF contest last June.

Dave
N6ORB
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W3HKK
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« Reply #2 on: March 03, 2011, 09:07:54 AM »

Way to go Dave!. 

I  made a few hundred qsos last Es season  but alas a virus  hit my log and I lost most of them. :< 

After 55 yrs in ham radio it was my first time on six!  And a real blast.  Im thinking  since a half wavelength on six is 10 ft, then 10-20 ft off the ground should be mighty effective.  So until I get a tower back up...if I do...the next step is some emt conduit  and  a  10 ft high yagi for  the next Es season.   

With so many new rigs having six m capability, and the improved  vhf performance of such rigs,   six ought to be a fun place  to spend MAY-JUN-JUL!  I gotta think the activity level is many times what it was in the past.

How do you put away and set up your moxon? Just throw a tent over it?  Hide it in the bushes?  Roll it out of the family room  onto the back deck or patio?    Mine is sitting in a patio umbrella base, tied to the propane grill.  I can see it from the shack but have to trot out the back door to turn it....maybe a 75 ft trip each way. Rotator by Armstrong!
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N6ORB
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« Reply #3 on: March 03, 2011, 11:02:55 AM »

Sorry to hear about the loss of your log. I still log on paper, except for HF contests. I've been uploading everything to LOTW for nearly a year, so I feel pretty safe now.

As for the Moxon, I was using two telescoped sections of PVC pipe for the mast. The Moxon slips on top. When I'm done, I just lay the mast on the patio and lean the antenna against the fence until I'm ready to operate again.

Last fall I bought some  fiberglass military surplus camouflage support poles. Now my mast breaks down to short sections that I can put in the trunk when I go portable or roving. With my new mast, I can get the antenna up to 16.5 feet without guying. I should be working JAs easily this summer. :-)

Dave
N6ORB
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W3HKK
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« Reply #4 on: March 03, 2011, 02:34:32 PM »

Nice set up.  I thought about the fiberglas surplus masts but then read several comments by users who had them fail  while in use, presumably due to aging.    Im always on the lookout for a solid build push up mast to get 15-25 ft off the ground, be it for the 6m yagi at home, or at FD, the Ohio QSO Party,  and a few other contests the club likes to do.

In the old days you could always get  aluminum push up masts, or steel lt wt push up masts at Radio shack or many other places, but sadly those supplies have all but disappeared. :<

I  do update to eQSL every few weeks, and print out paper copies every few months, but usually not before the HD crashes for some reason!

I spent some time at Travis AFB n/o SF back in 67.  Got to drive around CA from Orange Co up to Sacramento-Russian River-Napa/Sonoma Vallies-Yosemite.  It was a terrific year but not much hamming other than at the MARS station running phone patches  from NAM. Ah the good old days.
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WB2QIG
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« Reply #5 on: March 03, 2011, 06:35:29 PM »

Speaking of masts, I too got mine from Lafayette Radio and it was a 50 foot mast. Only had a small beam and a rotor on it but it was PERFECT for strapping to the chimney. I'd love to find one again and be back on 6M SSB in a flash.
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WB6BYU
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« Reply #6 on: March 04, 2011, 08:44:18 AM »

Quote from: W3HKK
...I thought about the fiberglas surplus masts but then read several comments by users who had them fail  while in use, presumably due to aging.    Im always on the lookout for a solid build push up mast to get 15-25 ft off the ground...


The military surplus mast sections come in both fiberglass and aluminum.  The latter is much
better for long term use.  They're easy to put up if you stack them vertically - start with the
antenna on top of a couple of sections, pick up the stack while leaning it against the guys,
and slip the next section in underneath.
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N2SLO
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Posts: 65




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« Reply #7 on: March 05, 2011, 04:22:55 PM »

How low can you go and still work  effective Es?  

Last May I bought a 5 el yagi and put it up 6 ft off the patio. Running 100w I worked 37 states and 4 countries including EU.  Worked the entire west coast beaming THRU the house during May-Jul.  

Now that was fairly effective but I could tell it wasnt keeping up with the average bear.

So Im curious how others with   5 el yagid and 100w do with low antenna hts like 10-15-20-25 ft or so?

Great question. My 2 element quad is up at 25 feet (see QRZ for picture). I made VUCC, and have almost 200 grids confirmed, all with under 200 watts of power. I think 20 feet at 6M is one wave length (correct me if I am wrong), and this is a good hight for 6M beam. Smiley
« Last Edit: March 05, 2011, 04:24:45 PM by N2SLO » Logged
W3HKK
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« Reply #8 on: March 06, 2011, 02:20:24 PM »

N2SLO:  your experience is encouraging.  I know  with my antenna at 6 ft there were plenty of itmes when I called but was covered up by stronger signals.  Hoping with a 20-30 ft push up mast to  elbow my way in a little more often.  And it sounds like you did just that.  1 wavelength antenna  ht should in theory be pretty productive in many if not most circumstances.

We will soon find out.

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KM3F
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Posts: 506




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« Reply #9 on: March 06, 2011, 07:17:38 PM »

There are a lot if hams that think in terms of straight off and inline with the boom of an antenna for performance.
These are the people who have never looked at antenna theory or much about propagation.
I just had a friend of mine who assumed the same thing until I explained a little of it to him.
Es comes in at an angle from the sky, horizon etc not straight into the boom plain of the elements.
As such, height does not mean that much under 'those' conditions "except" the height influence on pattern sensitivity. If the signals are strong the antenna can lay on the ground but the transmiter won't be happy about the mismatch it sees.
It is a different situation when Tropo  is the working desire. With this, height is all important because the antenna 'is' looking at the closest horizon be it a hill, a building or whatever.
Then reception and transmission is more inline with the plain of the elements.
Under these conditions, you can make contacts quite far out of line of sight because of scatter over the edges of the obstruction in the distance.
It's important to take a look in the books for how this all works.
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WB2WIK
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« Reply #10 on: March 06, 2011, 08:52:49 PM »

N2SLO:  your experience is encouraging.  I know  with my antenna at 6 ft there were plenty of itmes when I called but was covered up by stronger signals.  Hoping with a 20-30 ft push up mast to  elbow my way in a little more often.  And it sounds like you did just that.  1 wavelength antenna  ht should in theory be pretty productive in many if not most circumstances.

We will soon find out.



1 WL on 6m is only 20'.  If I drop my 6m beam to 20' I lose most of what I usually hear, when it's at its normal height of 65 feet.

The difference is rather huge.  If I could practially put my 6m beam at 120' I'd definitely do that, but that would be very difficult here in the city on a small lot.

Anyone who thinks that a 6m beam works well at 20' above ground never tried the same beam up higher.
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KF6A
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« Reply #11 on: March 06, 2011, 11:50:43 PM »

.......So Im curious how others with   5 el yagid and 100w do with low antenna hts like 10-15-20-25 ft or so?
I did fairly well with my 5 ele yagi up about 21' but when the propagation went long I was left high and dry whereas guys with higher yagis were still working people that were now at my noise level or completely inaudible. When the new 6m yagi goes up at the new QTH it will (hopefully) be going up twice as high, at least 40'. I ran some EZNEC simulations to see what was going on and you lose a lot at low angles with the antenna at 21'. Raise it to 40' and you gain ~5dbi at 2deg elevation. That extra 5db could be the difference between hearing them or not but all is not lost if you cannot do 40'. Raise that same antenna up to 65' and EZNEC says it should be 9dbi better at 2deg elevation compared to the same 5ele at 21'. That is a HUGE improvement over 21'.

That said, unless you live on a hill you probably wont be opening or closing the band with your 5ele at 20' BUT it should work fine most of the time. Either way try to get it up as high as you can for max fun.
« Last Edit: March 06, 2011, 11:54:18 PM by KF6A » Logged
W3HKK
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« Reply #12 on: March 07, 2011, 06:46:15 AM »

Well, help is on the way. 

Im  looking at a 56 ft aluminum tower similar to what I used for 20 years, and once I pick  the hf antenna to go on top, the  5 el yagi will go on top of that.  But that wont happen til Fall.

Which brings up the classic question:  How far above a five band yagi do you put a 6m yagi for minimal interaction.  Not perfection, mind you, but minimal interaction.  Im looking at  maybe 5 ft as desirable from a wind load standpoint on 2"  6061T6 quarter inch mast.  And that was  the spacing between my 20m monobander and my 10-15m yagi in past years.

But to get thru the Es season, I'll be  using a 20 ft mast this year on an interim  basis.

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KF6A
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« Reply #13 on: March 07, 2011, 01:02:23 PM »

.....Which brings up the classic question:  How far above a five band yagi do you put a 6m yagi for minimal interaction.  Not perfection, mind you, but minimal interaction.  Im looking at  maybe 5 ft as desirable from a wind load standpoint on 2"  6061T6 quarter inch mast.  And that was  the spacing between my 20m monobander and my 10-15m yagi in past years.
Find the stacking distance for your antenna and you can try 1/2 that spacing. But without modeling or physically trying it's just a guess.


Quote
But to get thru the Es season, I'll be  using a 20 ft mast this year on an interim  basis.
Last Es season I worked 48 states, 325 grids with my best DX being JA and CT with my 5ele yagi up 21' from San Fran so it isn't that bad. But it would be nice to have it higher.
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