Home |
Search |
Today's Posts |
|
#1
![]() |
|||
|
|||
![]()
Who sells them with the most bang for the buck?
|
#2
![]() |
|||
|
|||
![]()
Depends what you want. Are you going to use a small Yagi for FM work or
a long boom Yagi for SSB/CW? If you want something fairly simple, a homemade 6 or 8 element Yagi is fairly simple. Otherwise, for some serious weak signal work, the K1FO designs are quite commonly used. Directive Systems sell them... http://www.directivesystems.com/antenna4.htm Hope that helps! Scott N0EDV Merlin-7 KI4ILB wrote: Who sells them with the most bang for the buck? |
#3
![]() |
|||
|
|||
![]()
What design plans would you use?
Thanks joe "Scott" wrote in message .. . Depends what you want. Are you going to use a small Yagi for FM work or a long boom Yagi for SSB/CW? If you want something fairly simple, a homemade 6 or 8 element Yagi is fairly simple. Otherwise, for some serious weak signal work, the K1FO designs are quite commonly used. Directive Systems sell them... http://www.directivesystems.com/antenna4.htm Hope that helps! Scott N0EDV |
#4
![]() |
|||
|
|||
![]()
"Merlin-7 KI4ILB" wrote in message
... What design plans would you use? Thanks joe Are you an Internet only type of person? The original design was perfected by Steve Powlishen, K1FO, who spent hundreds of hours optimizing yagi designs on a high powered Hewlett Packard computer. He started with some computer optimized designs of Tom Kirby, W1EJ, (SK) who was using computer software developed at Ohio State University. W1EJ had came up with many excellent VHF long yagi designs. The finished K1FO designs were carefully checked out in the real world by K1FO to ensure accuracy of the design effort. His efforts have produced an exceptional design with maximum gain very close to the maximum amount possible, while keeping side lobes, (particularly those of the H-plane) at a very low level. The net result is broad bandwidth, wide beamwidth, and clean lobe structure. Clean H-plane patterns translate to efficient stacking with maximum possible gain and manageable array side lobes. The design has been published in MANY printings of the ARRL Handbook. gb |
#5
![]() |
|||
|
|||
![]()
If you don't mind having a little less gain than is ultimately possible
by using an antenna modeling program, the NBS (Nation Bureau of Standards) designs are pretty straight-forward. For a 6 element Yagi, here is element lengths and spacings for building with insulated elements (insulated from the boom, so I would use wood, 1" X 2" X 8.5') Lengths: Reflector = 3' 4" Driven = 3' 2-3/16" Dir 1 = 3' 7/8" Dir 2 = 3' 7/16" Dir 3 = 3' 7/16" Dir 4 = 3' 7/8" Spacing: Ref to Driven = (187.2/Fc) X 12 Spacing between all other elements = (234/Fc) X 12 where Fc is the design center frequency in MHz, ie 146 for the center of the FM portion). The spacing calculations give the answer in inches. Then you need to feed it. I use delta matches. Are you good at qrz.com? If so I can send you a drawing of the feed to get you started (but you would need an SWR meter that works at 2M to get it adjusted). Scott N0EDV Merlin-7 KI4ILB wrote: What design plans would you use? Thanks joe "Scott" wrote in message .. . Depends what you want. Are you going to use a small Yagi for FM work or a long boom Yagi for SSB/CW? If you want something fairly simple, a homemade 6 or 8 element Yagi is fairly simple. Otherwise, for some serious weak signal work, the K1FO designs are quite commonly used. Directive Systems sell them... http://www.directivesystems.com/antenna4.htm Hope that helps! Scott N0EDV |
#6
![]() |
|||
|
|||
![]()
Scott wrote:
If you don't mind having a little less gain than is ultimately possible by using an antenna modeling program, the NBS (Nation Bureau of Standards) designs are pretty straight-forward. For a 6 element Yagi, here is element lengths and spacings for building with insulated elements (insulated from the boom, so I would use wood, 1" X 2" X 8.5') Lengths: Reflector = 3' 4" Driven = 3' 2-3/16" Dir 1 = 3' 7/8" Dir 2 = 3' 7/16" Dir 3 = 3' 7/16" Dir 4 = 3' 7/8" Spacing: Ref to Driven = (187.2/Fc) X 12 Spacing between all other elements = (234/Fc) X 12 where Fc is the design center frequency in MHz, ie 146 for the center of the FM portion). The spacing calculations give the answer in inches. Then you need to feed it. I use delta matches. Are you good at qrz.com? If so I can send you a drawing of the feed to get you started (but you would need an SWR meter that works at 2M to get it adjusted). Scott N0EDV NBS yagis were quite horrible actually. Not good gain, horrid bandwidth, high sensitivity to build errors , crummy patterns compared to anything since the early 90's. Don't bother. tom K0TAR |
#7
![]() |
|||
|
|||
![]()
I won't debate the differences in patterns, as I have no data on the
patterns for the NBS designs. In the ones I've built, gains measured were pretty close to what they claimed and the claimed gains of the K1FO style antennas from Directive Systems http://www.directivesystems.com/antenna4.htm (for the same number of elements) is usually within a quarter to a half of a dB of the claimed gains of the NBS designs. I didn't notice a high sensitivity to build errors. I used the design lengths and diameters of the elements on a wood boom. On my 222 version, I used the T match (same thing as the K1FO designs) and all I had to do was shorten the driven element to get zero reflected power (which was expected since you need to make the driven capacitive to tune out the inductance of the matching rods). Not sure what you mean by horrid bandwidth...are the NBS designs too narrow or too wide? Again, I've never noticed that as being a problem because I only use my (222 for example) antenna from about 222.100 to 222.150. Scott N0EDV Tom Ring wrote: Scott wrote: If you don't mind having a little less gain than is ultimately possible by using an antenna modeling program, the NBS (Nation Bureau of Standards) designs are pretty straight-forward. NBS yagis were quite horrible actually. Not good gain, horrid bandwidth, high sensitivity to build errors , crummy patterns compared to anything since the early 90's. Don't bother. tom K0TAR |
#8
![]() |
|||
|
|||
![]()
Scott wrote:
If you don't mind having a little less gain than is ultimately possible by using an antenna modeling program, the NBS (Nation Bureau of Standards) designs are pretty straight-forward. For a 6 element Yagi, here is element lengths and spacings for building with insulated elements (insulated from the boom, so I would use wood, 1" X 2" X 8.5') Lengths: Reflector = 3' 4" Driven = 3' 2-3/16" Dir 1 = 3' 7/8" Dir 2 = 3' 7/16" Dir 3 = 3' 7/16" Dir 4 = 3' 7/8" Spacing: Ref to Driven = (187.2/Fc) X 12 Spacing between all other elements = (234/Fc) X 12 where Fc is the design center frequency in MHz, ie 146 for the center of the FM portion). The spacing calculations give the answer in inches. Then you need to feed it. I use delta matches. Are you good at qrz.com? If so I can send you a drawing of the feed to get you started (but you would need an SWR meter that works at 2M to get it adjusted). Scott N0EDV Sorry, I didn't give an alternatives in my previous email. Please see the K1FO series in the ARRL antenna books. They are among absolutely the best possible, very replicable,, low build sensitivity, and fairly short to very long boom plans are available. If you do not have one of the ARRL Antenna books available, I, or others here, have copies as needed. tom K0TAR |
#9
![]() |
|||
|
|||
![]()
Thanks for all the information everyone...
The only ARRL antenna book I have is the one on wire antennas, If you could suggest one that covers yagi antennas in detail, I am sure they still sell it. I think that I could build one a lot cheaper than buying one and learn something at the same time. I would like the best gain possible (who wouldn't) However, I need something that has the smallest lobe(s) off the sides and back. (I know the two more or less coincide with each to a large degree. To give you an idea of what I am trying to do...I have some land in Richlands NC. I am a member of several ham clubs in the Charleston,SC area that has repeaters fairly close to the SC,NC state lines. I would like to be able to make it into one of those repeaters from Richlands, NC. (that may only work when the bands open up every now and again) I do not want to key up every repeater on the same freq. to the sides or the back of the antenna. So I bow down to the elmers and those who can point me in the right direction. BTW. the antenna will be at least 60' high but possibley up to 110' high depending on tower funds when I move. Im good at QRZ and ARRL Thanks again Joe KI4ILB Solar powered ham radio "Tom Ring" wrote in message .. . Scott wrote: If you don't mind having a little less gain than is ultimately possible by using an antenna modeling program, the NBS (Nation Bureau of Standards) designs are pretty straight-forward. For a 6 element Yagi, here is element lengths and spacings for building with insulated elements (insulated from the boom, so I would use wood, 1" X 2" X 8.5') Lengths: Reflector = 3' 4" Driven = 3' 2-3/16" Dir 1 = 3' 7/8" Dir 2 = 3' 7/16" Dir 3 = 3' 7/16" Dir 4 = 3' 7/8" Spacing: Ref to Driven = (187.2/Fc) X 12 Spacing between all other elements = (234/Fc) X 12 where Fc is the design center frequency in MHz, ie 146 for the center of the FM portion). The spacing calculations give the answer in inches. Then you need to feed it. I use delta matches. Are you good at qrz.com? If so I can send you a drawing of the feed to get you started (but you would need an SWR meter that works at 2M to get it adjusted). Scott N0EDV Sorry, I didn't give an alternatives in my previous email. Please see the K1FO series in the ARRL antenna books. They are among absolutely the best possible, very replicable,, low build sensitivity, and fairly short to very long boom plans are available. If you do not have one of the ARRL Antenna books available, I, or others here, have copies as needed. tom K0TAR |
#10
![]() |
|||
|
|||
![]() "Scott" wrote in message .. . Depends what you want. Are you going to use a small Yagi for FM work or a long boom Yagi for SSB/CW? If you want something fairly simple, a homemade 6 or 8 element Yagi is fairly simple. Otherwise, for some serious weak signal work, the K1FO designs are quite commonly used. Directive Systems sell them... http://www.directivesystems.com/antenna4.htm Hope that helps! Scott N0EDV Now you tell me. I just ordered 2 beams from M-Square, one for 432 and one for 144. Wish I had the K1FO antennas as I had one for 432 and it worked very well. I did not know anyone had picked up the K1FO design after he became a SK. |
Reply |
|
Thread Tools | Search this Thread |
Display Modes | |
|
|
![]() |
||||
Thread | Forum | |||
Odd signal meter phenomenon | Shortwave | |||
SWR meter vs TLI | Antenna | |||
SWR meter kaput? | Antenna | |||
Triplett 3423 meter movement help needed | Equipment | |||
Fwd: Bible Voice A04 Schedule | Shortwave |