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Author Topic: Best dummy load antenna?  (Read 8055 times)
IZ8FFC
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Posts: 11




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« on: January 28, 2014, 11:10:16 AM »

Hello everybody,
I would ask you which dummy load antenna do you prefer to go QRP.
I don't really like a lot the miracle one... I am looking at something more "performing".

I trasmit with FT 817, I got a Emtech ZM 2 tuner, and i was looking at RHM 5 or 8b antennas by Diamond.
Does anyone has any experience from these?

Do you think are they good or not?
Please share with me your experience.

Thank you a lot
73 de IZ8FFC
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K8AXW
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Posts: 4004




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« Reply #1 on: January 28, 2014, 02:47:26 PM »

FFC:  A dummy load is a dummy load.  What you are looking for is a dummy load that will handle your power requirements and time restrictions, nothing more. 

Many use the 1 gallon oil filled dummy load and it sets on the floor out of sight.  If you ever plan to use QRO, then I suggest buying this style. 

If by more "performing" you mean a dummy load that has a built in meter then I can understand your question better.  In this case I would buy a Power/SWR meter like the Diamond SX-200  AND the oil can dummy load.
You would probably have better performance with this combination.




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IZ8FFC
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Posts: 11




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« Reply #2 on: January 28, 2014, 03:18:48 PM »

Hello AXW!
I was just kidding!!! I'd mean: a miracle duck antenna is not a proper antenna.
It is a miracle!!! If you do some qso.
Like miracle there are others like wonderwand antenna .. Etc Etc
Or diamond rhm 5 or 8b. There are too short antenna That many ham radio operators
Call them as DUMMY LOAD (hi hi).

So i was asking you... Who has tried the diamond one?? Which has the less "dummy LOAD" behavior??
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AA4PB
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Posts: 13033




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« Reply #3 on: January 28, 2014, 03:31:34 PM »

I've never used the Diamond antennas. They look like a short, heavily loaded vertical. The problem with a vertical is that their performance is heavily depended on what you use for radials. I've had much better luck with a dipole such as the Buddipole. It breaks down pretty small for transport yet provides much better efficiency (i.e. not too heavily loaded) on 20M and above and even works pretty well on 40M.

Of course, with the ZM2 tuner if you can find some supports to put up a longer wire you will do much better.
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IZ8FFC
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Posts: 11




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« Reply #4 on: January 28, 2014, 04:37:46 PM »

...so you advice me to carry  with me always the ZM2 tuner and just attach a wire of 3 - 4 meters lenght at red banana plug?
and try to work with a piece of wire?

73 de IZ8FFC
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AA4PB
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« Reply #5 on: January 28, 2014, 05:09:06 PM »

The wire needs to be longer than 3-4 meters to be efficient. I was thinking something between 1/4 and 1/2 wavelength on the band you are using. Then, because its end fed, you need to lay a couple of counterpoise wires on the ground. If the wire were exactly 1/4 wavelength then feed point current would be high and you'd have more loss in the counterpoise. If the wire were exactly 1/2 wavelength then the feed point current would be low and the loss in the counterpoise would be much lower. The tuner however, might have a difficult time matching the high impedance. If you shorten the wire to a little less than 1/2 wavelength you can lower the impedance to something that the tuner can easily match while at the same time keeping the feed current fairly low.

If you don't have the supports to put that much wire in the air then the Buddipole will probably be a better option.
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K8AXW
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« Reply #6 on: January 28, 2014, 08:09:43 PM »

FFC:  Sorry OM but I'm very slow anymore.  Before I put up my tower and beam antenna, I was forced to use a vertical antenna.  This housing development was built on a grass strip airfield.  No trees.

I referred to my vertical as "My inverted ground rod" if that tells you anything.  It got me on the air but was a constant source of frustration.

One other mentioned radials and was correct.  Putting down radials is a royal PITA.  I installed several but the antenna was still a dog.

Good luck.
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W1JKA
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Posts: 1821




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« Reply #7 on: January 29, 2014, 04:16:58 AM »

Re: IZ8FFC

Use your browser: [Portable QRP YouTube Videos] especially the series by "Goathiker". All the QRP  antenna info you will ever need either homebrew or commercial.
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IZ8FFC
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Posts: 11




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« Reply #8 on: January 29, 2014, 05:59:47 AM »

The wire needs to be longer than 3-4 meters to be efficient. I was thinking something between 1/4 and 1/2 wavelength on the band you are using. Then, because its end fed, you need to lay a couple of counterpoise wires on the ground. If the wire were exactly 1/4 wavelength then feed point current would be high and you'd have more loss in the counterpoise. If the wire were exactly 1/2 wavelength then the feed point current would be low and the loss in the counterpoise would be much lower. The tuner however, might have a difficult time matching the high impedance. If you shorten the wire to a little less than 1/2 wavelength you can lower the impedance to something that the tuner can easily match while at the same time keeping the feed current fairly low.

If you don't have the supports to put that much wire in the air then the Buddipole will probably be a better option.


Thanks everybody for messages.
I would trasmit on 20 - 17 - 15 meters band. That's my idea.
Sincerely I got some supports where to throw the wires.
So, what lenght do you think I need for 20-17-15 meters band?

I was thinking at MINI DIPOLE antenna too.
What do you think a 3 meters (total lenght 6 meters) lenght with trapped coil in the middle for each arm?
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W4KYR
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Posts: 622




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« Reply #9 on: January 29, 2014, 09:36:15 AM »

 "Gotham Antennas" could qualify for the 'dummy load category'.

 Perhaps with a Gotham Antenna and along with the legendary Eico "Seven Drifty Three" it would be a nostalgic trip down memory lane be better to jump off a cliff.

http://www.eham.net/reviews/detail/4094

Read the 'glowing' reviews below

Quote
Then again, some memories are best left in the past.

Quote
What became of the Gotham? I pulled the aluminum sections apart and put big notches in them..my mom used them as aluminum clothes poles to hold up the laundry as it was outside drying..there the Gotham worked great.

Quote
I wonder if other hams have had major life issues as a result of owning this antenna.


Quote
Absolute total junk

Quote
Not worth the wholesale price of aluminum.

Quote
A very cheap antenna with poor performance. Gave verticals a bad name.

Quote
Destroyer of novice careers  
« Last Edit: January 29, 2014, 09:48:04 AM by W4KYR » Logged

Still using Windows XP Pro.
AA4PB
Member

Posts: 13033




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« Reply #10 on: January 29, 2014, 10:49:57 AM »

I would trasmit on 20 - 17 - 15 meters band. That's my idea.
Sincerely I got some supports where to throw the wires.
So, what lenght do you think I need for 20-17-15 meters band?

I was thinking at MINI DIPOLE antenna too.
What do you think a 3 meters (total lenght 6 meters) lenght with trapped coil in the middle for each arm?

I'd try something about 10M in length for the antenna. You can then adjust the length a little if your tuner has trouble matching it.

The MINI DIPOLE is quite similar to the BudiPole that I mentioned. 6M total length is about half the length of a full sized 1/2 wave dipole on 20M. I've found that if you make the length at least half of "full sized" then the efficiency doesn't suffer too much, so your idea should work well. I've found that once you get the antenna ten feet above ground that it doesn't detune as you go higher.
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K1WJ
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Posts: 464




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« Reply #11 on: January 29, 2014, 12:42:35 PM »

I use a MFJ-1979 17ft telescoping whip, can adjust for 6m,10m,12m,15m,17m,20m as a full size 1/4 wave vertical antenna. I have base of antenna at 4ft off the ground held up by tripod. Use a single 1/4 wave elevated radial for band of choice also 4ft off the ground also held by another tripod on insulated end.
17ft vertical whip retracts to 2.5ft when not in use. Great for HOA or portable ops. It is No dummy load........
73 K1WJ David
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IZ8FFC
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Posts: 11




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« Reply #12 on: January 29, 2014, 05:15:26 PM »

Thank you K1WJ.
I am very interested in your solution.
How do you tune this 17ft telescoping whip? What tune do you use? I just bought on ebay a adapted 3/8 to pl259 to adapt
a 3/8 mast from MP1 superantenna I got on my EMTECH ZM2 tuner.

What do you think ? is this a good solution? But once I connect this whip or if I buy your whip...how can I add the counterpoise?
I mean...on the EMTECH zm 2 tuner...

If i connect the whip on the pl259...how can i add my counterpoise?
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AA4PB
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Posts: 13033




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« Reply #13 on: January 29, 2014, 05:32:03 PM »

I don't think a PL-259 and the ZM2 is going to physically support a 17-foot whip. You need to mount the whip on some other mount and run a short piece of coax from the whip to the ZM2. The center conductor goes to the whip and the shield goes to the counterpoise.
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WB6BYU
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Posts: 13582




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« Reply #14 on: January 29, 2014, 06:14:29 PM »

Quote from: IZ8FFC

How do you tune this 17ft telescoping whip?



One way is simply to telescope the whip to be a quarter wave on the band of operation.
No tuner required.




Quote

...how can I add the counterpoise?




The counterpoise should go to the black terminal.
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