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Is this worth my time, MFJ-1789 ?


fourstringburn

W9WDX Amateur Radio Club Member K5KNM
Feb 11, 2007
2,096
1,903
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mfj 1789.$359.95
http://www.mtcradio.com/mfj-1789-rotatable-dipole-9-bands/

Is this a good place to start?I have limited space, and would mount below my Sirio 2016....or some place e;se if need be.
Thank you.
It is a compromise type antenna mainly because it has loading coils. It does have capacity hats to make up some of the coil losses.

Put a lightweight rotor on it and for a limited space such as you have, I would say go for it.

I would use this one over those vertical contraptions such as the Butternut or the Hustler BTV series.
 

Mudduckmobile

Well-Known Member
Oct 5, 2015
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It is a compromise type antenna mainly because it has loading coils. It does have capacity hats to make up some of the coil losses.

Put a lightweight rotor on it and for a limited space such as you have, I would say go for it.

I would use this one over those vertical contraptions such as the Butternut or the Hustler BTV series.
still looking into things. The cap hats are one of points that mane me want to look closer at this antenna.
 

Captain Kilowatt

Professional Amateur
Staff member
Apr 6, 2005
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It is a compromise type antenna mainly because it has loading coils. It does have capacity hats to make up some of the coil losses.

Put a lightweight rotor on it and for a limited space such as you have, I would say go for it.

I would use this one over those vertical contraptions such as the Butternut or the Hustler BTV series.

Really? At only 14 feet it is less than half size on 20m and less than 1/4 size for 40m. At least a properly installed vertical such as the Butternut or Hustler BTV series is going to be more efficient simply due to length. The 5BTV is 24 feet tall. I'll let you know in a couple weeks how the 5BTV works as I am installing one this week along with the 17m add on kit.. Following DX Engineering's recommendations it is supposed to exceed the performance of that MFJ mini dipole.
 

fourstringburn

W9WDX Amateur Radio Club Member K5KNM
Feb 11, 2007
2,096
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NEW MEXICO
Yes really
Really? At only 14 feet it is less than half size on 20m and less than 1/4 size for 40m. At least a properly installed vertical such as the Butternut or Hustler BTV series is going to be more efficient simply due to length. The 5BTV is 24 feet tall. I'll let you know in a couple weeks how the 5BTV works as I am installing one this week along with the 17m add on kit.. Following DX Engineering's recommendations it is supposed to exceed the performance of that MFJ mini dipole.
Yes really!

The cap hats on the dipole make up some of the losses.

The butternut is mostly all lossy loading coils and the Hustler has multiple resonator coils and some caphats. I've seen pics of the butternut fall down with ice loading, it's a heavy antenna on it's own. I wouldn't use it in ice prone regions.

A dipole at a good height above ground has a most of it's RF energy broadside as opposed to a vertical being omni at near equal dispersment

Plus this dipole can be rotated for best signal direction.

All these antennas will work. If you were to test them side by side at your own station with your soil, terain, and other factors, then the comparisons would be more valid. Other than that, it would be the Rabbiporkchop test! :ROFLMAO:

My opinion on using the MFJ was primarily based on the fact the OP already has a vertical and with limited space, I think that antenna is a good option.
 

Captain Kilowatt

Professional Amateur
Staff member
Apr 6, 2005
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Yes really

Yes really!

The cap hats on the dipole make up some of the losses.

The butternut is mostly all lossy loading coils and the Hustler has multiple resonator coils and some caphats. I've seen pics of the butternut fall down with ice loading, it's a heavy antenna on it's own. I wouldn't use it in ice prone regions.

A dipole at a good height above ground has a most of it's RF energy broadside as opposed to a vertical being omni at near equal dispersment

Plus this dipole can be rotated for best signal direction.

All these antennas will work. If you were to test them side by side at your own station with your soil, terain, and other factors, then the comparisons would be more valid. Other than that, it would be the Rabbiporkchop test! :ROFLMAO:

My opinion on using the MFJ was primarily based on the fact the OP already has a vertical and with limited space, I think that antenna is a good option.

Those coils in the Hustler BTV series are traps not resonator coils with the exception of 80m where it is a resonator coil but the dipole does not cover 80m so that is moot. Almost half the length of the dipole element is made up of loading coils for the various bands.The cap hats on the dipole don't make up for some of the losses as much as they allow a smaller loading coil to be used but perhaps that is what you mean. Bandwidth on 40m IIRC is only about 40-50 KHz whereas the 5BTV will cover pretty much the entire band. As for " A dipole at a good height above ground has a most of it's RF energy broadside as opposed to a vertical being omni at near equal dispersment" that is true however this dipole does not have anything in the way of gain to take advantage of that. Even being omnidirectional the 5BTV is more efficient as long as a good groundplane is used. I have used short dipoles before and I am not a fan of them however I will be installing the QK-710 30/40m kit on my Explorer-14 next spring. It will be tuned for 40m but it is 42 feet long making it MUCH more effective on 40m than this dipole especially when installed at 63 feet. :D Given everything I would still prefer a BTV series with a GOOD groundplane.

Oh....and one last note. PLEASE do NOT ever compare me to Rabbiporkchop when it comes to making claims. :p
 
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fourstringburn

W9WDX Amateur Radio Club Member K5KNM
Feb 11, 2007
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NEW MEXICO
Even being omnidirectional the 5BTV is more efficient as long as a good groundplane is used.
This antenna has no gain either, it is generally used as a ground mounted vertical. Why not use a 43ft ground mount vertical with a remote tuner at the feed point and lots of ground radials??? No lossy traps or loading coils with those.

No question that a full size dipole at the right height is best.

All these antennas are compromise antennas for people with limited space to have multi-bands with 1 antenna. I haven't looked the Hustler antenna in quite a while and as so, I seemed to recall it having more than 1 resonator by I see it has mostly traps. Traps are lossy too!

Caphats do negate coil losses if large enough to where it can almost make up for the shortened length.

Example: My 2 ft mobile screwdriver antenna with a 2 ft mast and 15 in diameter 6 radial caphat tunes the 10 meter band with almost no added loading coil (antenna topped out ). It would take a 8 ft antenna with a small coil to do the same. So with the caphat radials and a little coil inductance, I get a 51 ohm impedance tuning with a 4 ft overall antenna length whereas a full 1/4 wave whip for 10 meters, the whip would be a 37 ohm feed-point. Wouldn't that equalize the efficiency between the short caphat antenna compared to the whip on that band?

Things aren't as cut and dry as the example given since the lower frequencies require longer antennas so shorter antennas rapidly decrease efficiency as the frequency lowers.

BTW, I wasn't comparing you to Rabbi, just was a humorous potshot to how he judges radios /antennas tunes and efficiencies to the "Verizon Test"... Can you hear me now!!! :D
 
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