Fiberglass antenna ?

[Cartoon Man]

Hello,

I have a question for you, out of the these two antennas, which one would use or performs the best...

Skipshooter 7 ft

or

Francis 8 ft ?

I am mounting on the top of the bed rail of my truck and I have an ALU. cap on the truck as well....

Thank you for your help,

 

[DXman]

I would probably go with the Francis 8.

 

[undertaker]

if you can go with the 102 steel whip!!!!!

 

[Switch Kit]

You will love the Fransis Amazer !! One of if not the best antenna I ever used on a vehical over the years , very close if not the same to the 102 inch S.S.W. and I think you would see a slightly better match from the Fransis , they love power also (-: Good Luck to you.

 

[undertaker]

where can you find the francis amazer???

thanks
bobby

 

[Master Chief]

You will love the Francis Amazer !!

There is only ONE "Francis Amazer". It comes in GRAY only. The part number for the Francis Amazer is CB-50.

There are other 8' Francis antennas in black, red, and white. These are CB-28.

Years ago, the CB-28 had only one wire in the fiberglass. The CB-50 had 3 wires embedded in the fiberglass, could handle more power, and is why they called them a "triple quarter-wave" antenna. Some people mistakenly thought the Amazer was a 3/4 wave antenna though. WRONG!

According to Barjan who now owns the Francis line, the CB-28 and the CB-50 both have 3 wires inside in order to streamline the manufacturing process. The Francis line is still manufactured in the same factory.

 

[Marconi]

Cartoon Man, another advantage of the Francis is that it will not likely bend as much as the steel whip. As the others have stated this is a very good antenna in my opinion.

 

[Cartoon Man]

Thank you all,

so it seems every one is saying go with the francis..... Now I plan on using the 6" spring with the antenna, will I still have to tune the antenna? I was thinking the skipshooter would have been the one to use with it's tip being able to tune.... The CB-50 is a little hard to find but there is a shop near the work place that has some in stock. Some one told me that they are not making the 8 footer any longer.

Once again, thank you,
Cartoon Man

 

[freecell]

"the CB-28 and the CB-50 both have 3 wires inside in order to streamline the manufacturing process. "

more horsepucky from barjan.


"a multielement antenna structure is provided which may be fabricated with a PREDETERMINED CHARACTERISTIC IMPEDANCE FOR IMPEDANCE MATCHING PURPOSES. the SEVERAL ELEMENTS COMPRISE ELONGATED ELECTRICAL CONDUCTORS GROUPED IN PARALLEL, LONGITUDINALLY EXTENDING RELATIONSHIP with the elements encased in a supporting body formed from a hardenable resin matrix. A BROADBAND FREQUENCY RESPONSE CHARACTERISTIC is obtained through appropriate selection of conductor diameters that will result in RESONANCE OF THE SEVERAL CONDUCTORS AT DIFFERENT RESPECTIVE FREQUENCIES WITHIN THE DESIGN FREQUENCY BAND."

http://www.firecommunications.com/patents/francis/us003541567-004.tif

Download AlternaTIFF Viewer Plug-in

 

[W5LZ]

If we're talking about the diameter of the conductor(s), the number of them in the antenna will make no significant difference at HF. There has to be a huge difference in diameter, 18 - 10 - 2 ga. wire just ain't gonna make much difference at all. If we're talking about the relative length(s) of conductors, there has to be more seperation between them than is practical in a fibreglass antenna (the usual ones anyway). That's at HF. VHF and above can be a different story.
The "horsepucky" part is true.
- 'Doc

 

[freecell]

that's what happens when you don't bother reading. if you had bothered (ever looked at a cross-section) you would know that the conductors are not located in the center of the glass. before the glass is taper ground the elements are the same general length. however during the taper-grind process the two conductors closest to the outer edge of the glass are shortened as a result. not only are the conductor diameters different, but the lengths are disimilar as well. as far as separation between the elements, all 3 of them are prevented from coming into contact with each other due to enamel insulation applied to at least 2 of the 3 conductors.

*"the 3 wires" (their spacing, length, material, diameter, placement, insulation, taper, etc.) have nothing to do with the manufacturing process and everything to do with the electrical properties presented at critical points of a three branched, open-ended parallel circuit and its efficient operation as a broadbanded, electromagnetic (antenna) transducer. any statement to the contrary of the one made at the beginning of this last paragraph* is "horsepucky." the circuit is designed and built first, then it is encapsulated.

here's a question for you. the CB28 and the CB50 are approximately 96" in length. where is the inductive reactance in the circuit compensating for the missing 6 inches in length (when compared to the steel 102") and an additional 5.5 inches usually comprised of the ball and spring when associating all of this to the overall physical length that we usually attribute to a resonant quarter wave element?

read the patent.

 

[W5LZ]

Oh my, a patent.
Governmentalized 'horsepucky' in quite a number of cases. After reading several of them I've wondered why the authors weren't laughed out of the Patent office. Then again, probably the clerks worry more about a document's form, operating procedures and spelling rather than it's content. Very large doses of salt (Exlax) is a requirement when reading patents.
- 'Doc

 

[freecell]

thanks for the excuses and the exaggeration, now how 'bout answering the question.

"here's a question for you. the CB28 and the CB50 are approximately 96" in length. where is the inductive reactance in the circuit compensating for the missing 6 inches in length (when compared to the steel 102") and an additional 5.5 inches usually comprised of the ball and spring when associating all of this to the overall physical length that we usually attribute to a resonant quarter wave element?"

 

[Marconi]

FC, I guess the answer to the question you pose has to lie in the ground plane affect if my conclusions are right.

Of course the fact that these Francis elements are electrically very thick compared to a single wire, likely adds bandwidth and that may tend to smooth things out as far as reactance goes.

I seem to find that as long as a 1/4 wave radiator is close to a resonant length, that changing that length has mimimal affect on resonance and matching as long as the ground plane affect is right. And if the GP affect is not right then changing the length still doesn't have much effect on resonance and cutting or adding won't get you there either.

 

[W5LZ]

freecell,
You'll find it in the same place that you find the inductive reactance which is seemingly present to make a 'normal' 102" whip appear resonant on 11 meters.
Now, you answer your own question.
I have to admit that there is a slight exageration in the patent thingy, but not near as much as you seem to think. And to the best of my knowledge, I didn't make any excuses. None were needed.
- 'Doc