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Francis Mobile Antenna

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Francis Mobile Antenna

Post by Scipio Kid » Wednesday, 28 March 2018, 5:45 AM

I recently picked up a couple of Francis Antennas mounted about 8" apart on a stainless steel bar with a pair of Vice-grips welded in between for quick mounting on a semi mirror. They each had a 12' length of good coax but the guy told me the long one (67") was for CB and the short one (31") for his stereo. I figured I'd need to buy a Peterbilt to use them, but my wife said no. So I cut the Vice-grips out, put 'em in my tool box and stowed the antennas and mounting hardware for the future figuring I'd test them out one day. Neither looked like a traditional CB antenna. They're just a thin fiberglass rod with no wire wound around the shaft and no plastic covering over the wire. I have a 102" fiberglass whip that's similar but much thicker and it works great. I have another, shorter one and it's junk. The SWR is off the scale with it so I figure it's for Ham or broke or not even an antenna.

The other day my brother picked up an old Chevy pickup for a side business and loaned it to me so I'd fix everything on it. Put an antenna mount on the front of the bed and mounted the long Francis on it just to see what it'd do. The SWR was fairly good, so I figured it had to be a CB antenna. I live in a canyon so it's not the best place for testing and, as usual, there wasn't anything but static on the radio. Called for a radio check and immediately heard a gal say something but didn't think she was responding to me. So I asked and she came in stronger and we talked a bit and I was impressed. I figured she had to be right, close by, since the conversation was so clear. I thought she was kidding when she told me she was Thirty miles north of me! I figured she had to be on a base with a big antenna, but she wasn't. And my radio's just an old Cobra 18 Ultra. Nothing special about it at all! After talking to her for several minutes, I decided that little Francis antenna was a great find!

I looked it up and it's called a pre-tuned antenna but apparently can be trimmed shorter by cutting the tip off with a hack saw. Other than that, I couldn't find much on it.

I'm wondering if anyone here has heard much about these antennas? Are they good, bad, ugly, cheap, expensive, reliable etc??, I'm sure impressed with this one, especially since I got the whole setup for 10 bucks. The Vice Grips were worth that.
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Re: Francis Mobile Antenna

Post by 295 antenna » Wednesday, 28 March 2018, 7:36 AM

I havent heard about those antennas in a very long time but if my memory serves me they are a good antenna and very popular back in the day.
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Re: Francis Mobile Antenna

Post by sonoma » Wednesday, 28 March 2018, 12:24 PM

Francis is a good antenna. they still sell them new and a 4 ft and longer works very good. the new ones that I have seen lately are called francis hot rod antennas. I have a 4 foot I use on one of my pickups.

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Re: Francis Mobile Antenna

Post by jessejamesdallas » Wednesday, 28 March 2018, 15:00 PM

Just don't run a bunch of power threw one, unless you really want to see some "Fire-N-da wire"...They are not flame proof... :mrgreen:
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Re: Francis Mobile Antenna

Post by MDYoungblood » Wednesday, 28 March 2018, 15:15 PM

I would buy a Francis antenna over a FireStik any day. So your saying the 31" long antenna is a CB antenna as well.
Years ago Francis had these adapter to run a pair of antennas side by side, worked well depending on the vehicle.
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The little fiberglass strip was a separator to tape midway up the antennas and a couple of jam nuts to keep the antennas from loosening up.

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Re: Francis Mobile Antenna

Post by Scipio Kid » Saturday, 31 March 2018, 7:45 AM

Thanks for the feedback guys. I haven't tried out the short one yet. Nor have I tried trimming the long one. I don't even know if it's long or short. Only checked it on channel 19 to make sure I wouldn't fry the radio.

Following the logic of Jesse James, I'm assuming they've run embedded wires within the shaft, maybe a coil from bottom to top. The top of the antenna is relatively narrow, maybe 1/4" so the coil or embedded wire would have to be tiny, made of very small gauge wire and I'd worry about just hacking off a portion at the top to trim it. I've tuned several "typical" fiberglass antennas by pulling the cap and cutting just a bit of the externally coiled wire off maybe one coil at a time. I'm also wondering if, instead of coiling the internal element, they've run a wire up and down the shaft, bottom to top, a few times to get the proper length rather than coiling it. If so, trimming at the tip would destroy the antenna.

I'll try out the short one today and see if it works. I used a CB antenna once for an AM/FM antenna and it didn't work well. In fact, the coax worked better without the antenna at all. I figured the CB antenna was tuned for 11 meter and had a hard time picking up the commercial frequencies. So, I was a little surprised the guy claimed he used it for his stereo.

And Greg, what was the use of the side-by-side setup you mentioned. Mine was very similar, but clearly homemade. I've seen dual antenna setups like this from time to time, mostly on semi-tractors, but is one used as a reflector for directional use or is one for AM/FM as the guy claimed mine was? Both my antennas were set up like CB antennas with coax attached. Neither was grounded to the vehicle (as if to be used as a reflector). If the set up you showed was for directional use, I'd be interested in hearing how and if they work and what advantages and disadvantages they have over a typical single antenna.

I've always heard dual antennas, particularly mounted up high on semi mirrors, create a narrow transmit / receive pattern way out in front and far behind the vehicle, much better for over the road travel than rather than a circular pattern only one antenna would generate. But would two antennas, mounted within inches of one another create that kind of effect?
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Re: Francis Mobile Antenna

Post by jessejamesdallas » Sunday, 01 April 2018, 6:55 AM

MDYoungblood wrote:
Wednesday, 28 March 2018, 15:15 PM
I would buy a Francis antenna over a FireStik any day. So your saying the 31" long antenna is a CB antenna as well.
Years ago Francis had these adapter to run a pair of antennas side by side, worked well depending on the vehicle.
ImageImage
The little fiberglass strip was a separator to tape midway up the antennas and a couple of jam nuts to keep the antennas from loosening up.

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You can still find them every now and then on the auction site...
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Do not argue with an idiot. He will drag you down to his level and beat you with experience.



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Re: Francis Mobile Antenna

Post by MDYoungblood » Monday, 02 April 2018, 13:29 PM

The Francis antennas are smooth, the loading coils are molded inside the fiberglass, unlike FireStik where it has a fiberglass rod with the wire wound around it and covered with shrink tubing. I never had the need to tune a Francis antenna so I'd check the SWR before thinking about it.

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