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Author Topic: Adding 440 to Indoor 144 MHz Yagi  (Read 6370 times)
K0OD
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« on: April 18, 2014, 10:55:17 AM »

Been upgrading my emergency radio capabilities as we enter tornado season. Bought a dualband 50 watt radio with WX alert feature and wide scanning ability. Replaced ancient RG8 mini coax with low loss LMR400. Now my old 2 meter 10-element Yagi in the garage is a monster at 14' off ground!   

But what to do about 440 which I've never worked before? I'd like to play with UHF as long as the transceiver covers it. Maybe dabble with satellites. Early tests support the common belief that UHF works better indoors than VHF.

Options:

 1) Just use my 2-meter Yagi on 440. I can get into several repeaters... sorta. SWR is unknown.

 2) Add a few 440-sized directors on the boom of my 144 Yagi to pick up UHF gain that way.

 3) Add small 440 Yagi above the 144 one. I presume I'd need a du/di-plexer in that case. Can't find anything online about acceptable minimum stacking distance. 2 to 4 feet would be about my maximum available spacing in the garage rafters.

 4) Replace old 144 Yagi with dualband 144/440 one.
   
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KA4POL
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« Reply #1 on: April 18, 2014, 11:10:42 AM »

Consider: http://www.arrowantennas.com/arrowii/146-437.html
Options 1 and 2 are not a good choice. Option 3 requires a diplexer as you noticed.
A dualband antenna like the Diamond X50 could be a solution, reviews are mixed: http://www.eham.net/reviews/detail/1054
For satellites the arrow would be fine.
I'd choose option 3, dedicated antennas are the optimum solution. Stacking distance of 4' should be sufficient.
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K9ZF
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« Reply #2 on: April 18, 2014, 11:44:13 AM »

1.  No good.  Unknown SWR will equal dead radio...

2.  A lot of trouble, for not much return...

3.  Best choice, if you want to stick with yagis.

4.  Will work, but not as efficient as option 3.


5.  Like KA4POL is pointing out, good dual band verticals are cheap and easy to find.  Plus no rotator worries.  Do you need the gain of the yagis, or will a good vertical do the job?  Simple is good, particularly for an emergency backup antenna.

73
Dan

--
K9ZF
Amateur Radio Emergency Service, Clark County Indiana. EM78el
The once and future K9ZF /R no budget Rover
 ***QRP-l #1269
Check out the Rover Resource Page at:
<http://www.qsl.net/n9rla>
List Administrator for: InHam+grid-loc+ham-books
Ask me how to join the Indiana Ham Mailing list!

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K9ZF
Amateur Radio Emergency Service, Clark County Indiana. EM78el
The once and future K9ZF /R no budget Rover
 ***QRP-l #1269
Check out the Rover Resource Page at:
<http://www.qsl.net/n9rla>
List Administrator for: InHam+grid-loc+ham-books
Ask me how to join the Indiana Ham Maili
K9ZF
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« Reply #3 on: April 18, 2014, 11:45:50 AM »

Forgot to add, 4 feet is plenty of separation between two small yagis.   Even closer may work in a pinch, but the pattern of the antennas may get skewed a bit.

73
Dan
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K9ZF
Amateur Radio Emergency Service, Clark County Indiana. EM78el
The once and future K9ZF /R no budget Rover
 ***QRP-l #1269
Check out the Rover Resource Page at:
<http://www.qsl.net/n9rla>
List Administrator for: InHam+grid-loc+ham-books
Ask me how to join the Indiana Ham Maili
G8YMW
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Posts: 267




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« Reply #4 on: April 18, 2014, 01:29:55 PM »

Here's my take

(1) Will work after a fashion, 70 cms is 3rd harmonic so SWR should be a match. Radiation pattern? Don't know

(2) Do-able, See http://www.qsl.net/dk7zb/Duoband/5+8_2m-70cm.htm Follow the measurements and should work

(3) Works

(4) Works

Would a good vertical be too big for indoors?

73 de Tony
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73 de Tony
Sent by WW2 Royal Navy signal lamp
WB2WIK
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Posts: 20665




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« Reply #5 on: April 18, 2014, 03:30:05 PM »

Radiation pattern will be plenty weird on 440 MHz because the elements are 3/2 wavelength long, so starting right from the driven element there isn't one main lobe, there are three: Two at angles skewed to broadside and one smaller one broadside to the element.  The two lobes that are skewed and thus not really aimed where you'd like them to be are actually "stronger" lobes than the centered one.

So, it should load up okay and probably work some repeaters and stuff, but will never actually work like a beam.

A 70cm vertical omni installed above the 2m beam would likely work better.
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WD9EWK
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« Reply #6 on: April 18, 2014, 03:38:44 PM »

<snip>

Options:

 1) Just use my 2-meter Yagi on 440. I can get into several repeaters... sorta. SWR is unknown.

 2) Add a few 440-sized directors on the boom of my 144 Yagi to pick up UHF gain that way.

 3) Add small 440 Yagi above the 144 one. I presume I'd need a du/di-plexer in that case. Can't find anything online about acceptable minimum stacking distance. 2 to 4 feet would be about my maximum available spacing in the garage rafters.

 4) Replace old 144 Yagi with dualband 144/440 one.
   

For option 4, WA5VJB has reference articles on his web site http://www.wa5vjb.com/references.html related to making your own Yagis.  If you look at the Cheap Antennas for Low Earth Orbit PDF on that page (http://www.wa5vjb.com/references/Cheap%20Antennas-LEOs.pdf), you'll see a design for a 2m/70cm Yagi on a single boom, and you can make it with your choice of elements used on each band.  If you don't have a diplexer, that article even has one you can make yourself. 

If you went with option 3 and didn't have a diplexer handy, build the one in the PDF I referenced above. 

Good luck, and 73!
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Patrick WD9EWK/VA7EWK
http://www.wd9ewk.net/
K0OD
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Posts: 2590




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« Reply #7 on: April 18, 2014, 10:14:14 PM »

Good info, guys. I was hoping there was some simple solution I had missed. Today I replaced my old coax. Theoretically that should improve 440 signals by about 6 db and 3.5 dB on 144. I'm seeing at least that. Even with my 2 meter Yagi, all the main 440 repeaters are now loud.

Below is a plot via DK7ZB of a 4-element 2 meter Yagi used on 440 MHz. It shows the three front lobes Steve mentioned. EZNEC shows about the same thing. SWR shouldn't be a big problem. There is a bit of gain and f/b on 440. I'm guessing the deep nulls will be diminished inside a garage. I've seen uglier patterns.

I'm going to stick with the 2-meter Yagi on both bands for the time being, especially since I just measured that I have less height than I thought. Placing a separate 440 Yagi or vertical alongside my 2-meter Yagi may eventually be the way to go.


 
  
« Last Edit: April 18, 2014, 10:19:43 PM by K0OD » Logged
KF7VXA
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Posts: 460




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« Reply #8 on: May 10, 2014, 08:54:44 AM »

I'm having a hard time figuring out why you have A Yagi at 14' in your garage. Are you not allowed to have an outside antenna or are you worried about weather damage ?
VHF/UHF is only line of sight plus a little extra.
Why not go to a high gain VHF/UHF vertical at a greater height and get more distance or even one that has lower gain, but is shorter and very stiff for wind resistance.
Check out my post in the EMCOMM section on the 14" UHF commercial antenna for $20.00. It is made by a professional antenna company, was made to go with a radio. No radio, but you get a 3 db gain collinier antenna that will stand up to any kind of weather and is in a Sched 80 PVC tube. I don't think any weather could kill it, offers a wide range of frequencies at SWR < 1.5 to 1. Then get a $38.00 arrow antenna for working satellites. I use the $20.00 antenna with a GMRS radio with 15 watts and cover the whole valley I live in with the antenna at 20'. It's the best deal on a UHF antenna you will find as it works as well as any lower gain antenna I've ever used.

I've just never seen a Yagi in a garage for VHF use. If antenna restrictions are a problem, I have no doubt you could find a better solution. The UHF antenna I mentioned can easily be hidden at a greater height. It's Gray and can be painted and put in something to hide it. It will offer a far greater range if up high than a yagi at 14' in a building.

Just wondering. You might think about getting your General license (it's easy) and upgrading to HF if you want some real range for Emcomm use. Get a 20/40 meter CCD antenna. It's a full wavelength dipole with capacitors on boards along the antenna. It will work excellent put under the lip of a wood fence held by plastic wire set off's. It even works laying on the ground (though not near as well as at height). Thing is, this antenna will get a lot of range without a lot of height. It's the only antenna that works at such low heights well that I have seen with low SWR (no snake oil, this antenna really works and works excellent).
Do a search for CCD antennas, you will find the company and info on who makes it and learn how it works. Mine is at 40' and gets out as good or better than a regular dipole at 50 plus feet. It can be bent 90 degrees in the middle for coverage in all directions.
A used HF radio can be found for a decent price. For EMCOMM, a HF radio is a must if you want more than just very local coverage.

73's John KF7VXA
« Last Edit: May 10, 2014, 08:57:44 AM by KF7VXA » Logged
K0OD
Member

Posts: 2590




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« Reply #9 on: May 10, 2014, 12:43:33 PM »

Quote
Just wondering. You might think about getting your General license (it's easy)

How do think I have a 1X2 call? Smiley

I passed the general at age 13 decades ago despite some real theory questions including drawing schematics and the requirement of copying 13 wpm Morse error-free for a minute. 1X2 calls were later obtainable by extra class ops... those who could, among other things, similarly handle 20 wpm code before FCC examiners.

I'm using the Yagi in the garage mostly because it's already there. It was used to hit a distant packet station long ago. Yes, I'm afraid of weather... like the tornado that destroyed Joplin MO and killed 158 people two years ago this month.  But mostly I'm looking for an indoor antenna that's somewhat safe to use in lightning storms.

UHF antenna
Quote
I don't think any weather could kill it

Weather sure killed this local TV tower in 1959. In the lower-left, you can make out what remained of the steel girder structure. Also killed 21 people. The old St Louis Arena, once home to the St Louis Blues hockey team, is at the top missing some of its roof.

K0OD
St Louis MO



 
« Last Edit: May 10, 2014, 12:49:25 PM by K0OD » Logged
KF7VXA
Member

Posts: 460




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« Reply #10 on: May 14, 2014, 02:36:09 PM »

OK, you are afraid of storms taking down your antennas. Storms are a fact of life. Antennas can be taken down or lowered. I'm betting if a twister of the type you are referring to hit your garage, your antenna would be toast also.

If you want to limit yourself because a twister might hit you directly or that you may take a direct lightning hit, it's your business, but you sure are losing out on a lot of contacts with your set up. But as I said, it's yours, not mine. I am into Ham Radio to make contacts with as many as possible. If my antenna gets damaged or ruined, I'll buy another. I may not put up a big tower, but there are many ways to get an antenna up in the air where it will work much better and make it so it can be taken down if necessary. Second choice is to use a lower priced antenna that works well and if it gets damaged, you don't loose much. Sorry I didn't look at your call sign before posting.
Just my 2 cents.

73's John KF7VXA
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KB2FCV
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« Reply #11 on: May 15, 2014, 08:33:38 AM »

This is a WA5VJB antenna I built and it cost maybe $20 to make

Here are some links on building his antennas:
www.wa5vjb.com/yagi-pdf/cheapyagi.pdf
http://www.wa5vjb.com/references/Cheap%20Antennas-LEOs.pdf
http://www.fredspinner.com/W0FMS/CheapYagi/vjbcy.html - I think I liked this guys take on them the best

I still use it for LEO satellite work and it works great.

« Last Edit: May 15, 2014, 08:39:04 AM by KB2FCV » Logged
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