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Author Topic: Old Cushcraft 11e 2 meter beam worth rebuilding  (Read 4904 times)
N4AEQ
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Posts: 91




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« on: May 14, 2013, 11:22:19 AM »

 I'm looking for a vertical 2 meter beam and found a old stacked set of 11 element Cushcraft beams, bent up and maybe could make 1 out of the pair.  Are they worth
repairing? I have read some threads on how these weren't that great, so any opinions? Should I look for a newer better design beam?
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K1CJS
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Posts: 6042




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« Reply #1 on: May 14, 2013, 12:30:10 PM »

I'm looking for a vertical 2 meter beam and found a old stacked set of 11 element Cushcraft beams, bent up and maybe could make 1 out of the pair.  Are they worth
repairing? I have read some threads on how these weren't that great, so any opinions? Should I look for a newer better design beam?

Weren't as great as what?  I'd wager to say that the beam would be better than an omni antenna in any event.  You could rebuild them--and possibly improve them a bit--and you would at least have a 2 meter beam for little $$.  If you need a 2 mtr. beam and don't want to spend much it's worth it.

On a similar subject, I got an older Hustler 2 meter colinear and rebuilt it--total cost to me was less than $30.  Beats the better than $170. price tag of a few years ago--a price tag that now is above $200. for a great 2 meter FM antenna.
« Last Edit: May 14, 2013, 12:34:20 PM by K1CJS » Logged
N4AEQ
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Posts: 91




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« Reply #2 on: May 14, 2013, 02:15:39 PM »

 Maybe just one person, they were complaining about the gamma match and common mode current problems and how they made it a decent yagi by going to a tee
match instead.  That's why I wanted to know if they were good beams or really had a problem, some antennas make good dummy loads and work as they should,
I though it would be better to find out now before I spent time and effort rebuilding it.
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WB6BYU
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Posts: 13335




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« Reply #3 on: May 14, 2013, 08:10:51 PM »

I have two of them - one missing the driven element.  It's not a bad beam, though
the design predates some of the newer techniques.  I'm not a big fan of the gamma
match, but you can change the fed method in the process of rebuilding it if you want.

Somewhere there was an article on changing the element spacings to make a 10 element
beam that works better - I don't have it handy, but will ask around and see if I can find
it.  At least you should have an assortment of elements and hardware that you can
use to build another design if you want.  From that perspective, it is probably worth
doing something with it if you want a beam, since basically they all use elements
(which can be scaled to use the diameter you have) on a boom (which you also have.)
The main difference will be in the lengths and spacings of the elements, which are
easy to modify as needed, plus the feed system (which can also be modified.)

You might start by looking at some of the other websites to see what designs they
use for a similar boom length:

http://www.qsl.net/dk7zb/
http://www.ifwtech.co.uk/g3sek/diy-yagi/index.htm
http://g4cqm.www.idnet.com/
http://www.g0ksc.co.uk/
http://www.yu7ef.com/
http://commfaculty.fullerton.edu/woverbeck/quagi.htm
http://www.wa5vjb.com/yagi-pdf/cheapyagi.pdf
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VA7VO
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Posts: 13




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« Reply #4 on: May 17, 2013, 08:41:27 PM »

These antennas were pretty good at the time of manufacture. Is it with the tri-reflector or standard single reflector?
Cushcraft and their engineers used an old concept from earlier yagi design from the 60's to produce the tri-reflector. I had some of these for 432 & 144 years ago, did the job.
There is inherently an unbalance of currents when using a gamma match however it's negligable.
Remember if you mount it vertically to use the support section from the boom down to about 5' made from fiberglass or other non metalic support or better than half the gain will be lost. The mast would disrupt the pattern.
Eznez models show that with the gamma the pattern is quite clean.

Build it up and good luck.

Glenn, VA7VO
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N4AEQ
Member

Posts: 91




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« Reply #5 on: May 19, 2013, 07:30:01 AM »

 Yea, I think everyone is right a gamma match is ok but tee would be better, I also noticed the 11e was dropped to 10e and
sounds like the spacing was why. I downloaded the PDF for 11e and quickly noticed all elements had the same spacing so that
threw up a red flag.
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WB0HZL
Member

Posts: 24




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« Reply #6 on: May 23, 2013, 04:30:16 AM »

Used the 11 element antennas for years - one for 147 MHz and one for 144MHz. Worked a lot of weak signal stations with those antennas. I even used one with 1 watt to a packet cluster over 60 miles away. Never had a problem with them. Well worth rebuilding. I never had any problems with the gamma match. I would like to find a couple more to stack for use on 2 Meter SSB and CW, the problem is shipping to my new home here in the Philippines. Anyway back to the question - I used them for years in Colorado and with the icing, snow and winds they always worked and never gave me any problems.

I did manage to bend the elements but they were not that hard to straighten - the little bends kind of gave the antenna  personality - hi hi hi. They can be mounted horizontally or vertically and I did both, if you want an omnidirectional antenna they are not the ones to use - mine had great F/B and easily nulled out the signals to the back.

If they are inexpensive I would say go for it and if they do not work the way you want getting your money out of them should not be a big problem.  Back in the old days these were great antennas and I still have mine and I still think they are great. My two cents worth.
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W3HKK
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Posts: 596




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« Reply #7 on: May 23, 2013, 07:23:29 AM »

Sounds like the Cushcraft Boomer.  I had one at 60 ft for years, beginning in 1980,  vertically mounted on an aluminum mast.  Had a terrific F/B...measured around 6 S units, and a F/S up around 9 S units.  The  pattern  was slightly non-symmetrical but at this point we are quibbling. 

It is well worth repairing IMO. 

BTW: I measured the F/B and F/S  from   repeaters in Columbus Ohio, about 70 miles away. Looking at Columbus I usually copied   signal strengths of 20-40 dB over S9.  Very impressive directionality.
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KB1GMX
Member

Posts: 780




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« Reply #8 on: May 31, 2013, 10:08:39 AM »

Good antenna and if free/cheap worth rebuilding.

The whole gamma thing is meaningless if installed vertical.  If horizontal
it has a small effect on the pattern.  Most of the fixes/mods are to get more
gain or better pattern but as is a good antenna.


Allison
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W6AOA
Member

Posts: 36




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« Reply #9 on: July 17, 2013, 05:56:09 PM »

I have one of those too. MFJ, who acquired Cushcraft, still stocks the parts for those antennas..
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