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Re: results of new US antenna design - advice sought
So to give an exit to this off topic issue and get back to the care and feeding of FT-817/FT-818 (my FT-817 S/N begins as "1D**** " and I bought it in 2001).?
For the original antenna design shortened with meander lines from 60 years ago: see page 15. This "Heaviside, Ph.D" is not to be confused with "Oliver Heaviside, FRS". A waste of perfectly good wire when a loaded mobile whip with a high (350) Q-loading coil and a "hat" would be more efficient. However the coiled up wire should make the losses sufficiently high enough to make it easy to "tune". I think I recall testing a crystal controlled 6L6 on 40M CW with a 50 watt light bulb. About fell over when I heard a reply from 450 miles away on an SX-99, back in the 1960's. . . I hated that receiver! Never quite knew what frequency it was tuned to. Had to key the transmitter to know for sure. The point is, even terrible antennas and sometimes things that are not antennas can sometimes "get out". Back to FT-817's and FT-818's! Jim/VEZ |
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Re: POWERPOLE CONNECTOR
On 2023-02-22 08:35, steve wellon via groups.io wrote:
Hi hopefully someone can help me out i have just purchased a powerpoleHullo Steve, Is this one of the wee blocks that bolts on to the rear panel of the radio, or a premade cable, or did you make it? Regardless, it may be a straightforward continuity problem. Check that out with your meter (DMM, what have you.) If you don't have one, yet, . . . that might be the next purchase. One may use other means as well. If it checks out, what about the supply cable that connects to it? In most troubleshooting situations adjust only one thing at a time. It isolates the changes made and helps understand the situation. There may indeed be times when a "shotgun" approach is warranted, however perhaps best to start off without that for now. Cheers, John -- J. D. Erskine VE7MHI VA7OTC CN88hk VA7RCN Victoria, BC |
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Re: results of new US antenna design - advice sought
Guys, stop arguing over a simple UK antenna idea that is nothing more than a dipole that has its ends folded
The forum is for FT817/818 not antennas Ken and Samudra, please take your argument elsewhere its gotten childish and abusive I am annoyed that people refer to the lack of US information on a UK antenna that is a single page in the Sprat magazine. I made this antenna back when it was published with cardboard and tape and it works.? If you have no experience with this modified dipole why argue back and forth about who is right and who is wrong? Lets get back to understanding why Yaesu discontinued the radio and why it never included a tuner -- John VE3IPS Radio is a Lifestyle not a Hobby Oprah added the ARRL Handbook to her list |
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Re: USB Interface for FT8?
You are welcome.
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I have two brands of USB Isolators that I required in the past with an IC-7200 and ICF-8101E using Dell laptop computers. But so far using the older FT-817, FT-847, TS-480SAT and TK-90 radios with Digirig I have not found the need. The IC-7200 at times would actually shutdown the computer from RF into the PC USB port, this was even with the use of TRIP-LITE USB cables that I tried as a remedy. If one id going to have a USB port RF issue its usually not until you go past about 50 watts unless you gave really bad ground loop issues. I have had a number of COTS AC'97 sound device interfaces over the years, the original U.S. Navigator which the designer consulted me about prior to manufacture were excellent for all my needs, the RigBlaster Advantage and now DigiRig.are much less expensive however, which is what most users are concerned about. I also have the Signalink USB, which are the only COTS units that have found that have audio issues on RX that most don't even realize they may have, unless they look carefully at their audio spectrum. The Signalink units often have high noise floors and many artifacts in their RX pass band. They also have too much TX delay with their VOX PTT operation for various COTS and MIL-STD data modes that can not be tailored to VOX PTT delays and lost data at TX start. I am familiar with these aspects due to developing such MIL-STD digital modes. Years ago I went so far as to create my own TI DSP BIOS based sound device interface to achieve the best audio I/O on a TI developers board for my HF Channel Simulator base band audio test bed which I later ported to a modified TI $10USB board for MARS members use. Which unfortunately soon after TI mysteriously discontinued. You may be interested in reading pages 20 onward to see what you want to have and don't want to have as to an audio pass band in your interface. When/If the FCC ever follows through on the elimination of the arcade 300 baud symbol rate rule, those Amateurs that will want to use high symbol rate modes via the software defined sound card approach will find just what their sound card interfaces can and can not support. The use of USB Codec based radios is the best as there is no analog cabling issues to deal with. /s/ Steve, N2CKH At 11:40 AM 2/21/2023, you wrote: Steve- tnx for the suggestion about digrig.? It does seem to be more flexible and I I like the idea of built in CAT.? |
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Re: results of new US antenna design - advice sought
Sam,
You misinterpreted my explanation of your design.? I suggest that the cage you have constructed acts a capacity hat (effectively "end loading") that add capacitance to the end of the antenna to bring into resonance.? While I will not dispute that the wire in your cage does in fact radiate, the field produced in each wire will cancel ( at least disturb the fields produced) the field in the adjacent wires as the current is opposite in phase.? As you mentioned in your original post, antenna analyzer software will have a hard time predicting a response.? And you would be correct unless you make the antenna segments very small which would just add to the complexity of the calculations needed to accurately plot the fields in each element.? With a 12 foot long cage, each wire is about 1/16 wavelength at 3.5 MHz.? That might help you visualize the current and field in each wire in the cage.? As the post above shows there are antenna designs that use capacitance hats to end load the antenna.? In that picture, you have essentially a trap design where each section of wires loads the adjacent trap.? Remember any antenna that is physically short exhibits a feed point impedance that is capacitive.? A designer can either add series inductance to cancel that out or add capacitance to the end to lower the feedpoint reactance.? As I said, I have no doubt your antenna will radiate.? However, I expect that your antenna compared to a full size dipole will produce lower radiated power. "Al,
You might read on how an antenna tuner works. Tuners do more than just make the radio happy. It will result in getting more power into the antenna/radiator.? Now what the radiator does with that power is another issue.? An 18ft vert on 80m does not work very well no matter what you do."Ron, maybe...Many people believe that a tuner makes more power in the antenna, but what it is actually doing is presenting a matched impedance as a load to the transmitter.? By definition, that should result in maximum power transfer between the transmitter and the transmission line.? However, that does not insure that full power will be delivered to the load.? It may result in more power at the antenna but there are a lot of variables that will produce losses in both the feedline and the tuner, and at the antenna end of the feedline there still is a mismatch to the feedline impedance.?? A simple online calculator for you 18 foot vertical predicts 0.025 % effeiciency for a total 2.5 watts with 100? watts input. -- Al Skierkiewicz WB9UVJ |
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Re: results of new US antenna design - advice sought
On Mon, Feb 20, 2023 at 09:55 PM, Ken N2VIP wrote:
was ever discussed in an ARRL publicationAs a multi-published author in QST (last May 2022 page 36) in order to be published in QST you have to meet specific standards. you are assigned an editor and a technical advisor. In my case he actually built my project and verified it did what I said it did. The editor is basically to fit the submission into space available in the magazine and maintain subject matter. I understands many submissions never make it to between the covers of QST, QEX or any of the other publications. What I don't know is what percentage submissions are rejected,? or if and when such antenna as discussed there was ever submitted. Speculation and my opinion would dictate it was never accepted for publication at best.? I also suspect a lot of what is found on the internet may have been rejected at one time, who knows. Antenna's such as the MFJ "cobweb"? and Rotatable dipole are only in there because MFJ pays for them to be there.I believe neither have ever been reviewed.? You may also notice antenna gains-Front to back Ratios are never specified in QST.. That's against ARRL advertising as those parameters can be manipulated. If antenna modeling? pick a software program; gain or Front to back ratio changes across bands just like SWR.. If you follow R.L Cebik W4RNL(SK) he would publish gains and Front to back and SWR in graphs of his many antenna examples. He was published in many ARRL articles. We emailed many times. and collaborated on an antenna R.L. found to be a revisit of a antenna used in the 1930 for HF point to point communions. Larry W8LM |
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Re: results of new US antenna design - advice sought
On Mon, Feb 20, 2023 at 11:35 AM, Samudra wrote:
Instead of the word "new" what would you you consider acceptable??REVISITED..... Your statement regarding experimentation and "improving" antennas. Is somewhat limited as not everyone has 25 acres of flat pasture land in Kansas to experiment in. like I do.. I really don't experiment much as like every body else. First I use EZNEC antenna Modeling software for the last 20 years. So I have a good idea as to what to expect. My antennas are limited to the environment I live in like everyone else.. Because of the open plains and bad weather- (Tornados) I don't throw any wires up in trees. Here in Kansas Typically a 35 foot telephone pole is higher than the trees that grow here naturally. I've lived back east where I climbed a spruce tree to use as a dipole end and at one point I was at least? 25- 30 feet above the telephone pole about 10 feet from the tree and the trunk of the spruce I was climbing was still 12 inches in diameter..? On the east coast you can launch a wire into a tree at 80 or 100 feet. Here in Kansas I have yet to see any trees over 40 feet.? So people do the best they can do- usually skimping. Today temperature is going to 68. I will be erecting Rohn 25 tower next to my barn. I have 20 feet up so I can install the Rohn side mount bracket to the barn and assemble the entire 50 foot tower with a hinged base. Once that's done and weather permits. Another 50 foot tower will be installed. Hand dug, cement made in a wheel borrow with a hoe and a garden hose like the last one. That tower will be equal and opposite of the tower I am working on today. The middle point is right over the ham shack and either? a loop or a double extended zepp will be installed with open wire feed. Only 50 feet? Here in Kansas it's flat and 50 feet gets line of site coverage for 60 miles in all directions. Now my "experimenting" with antennas certainly different than yours. I sure am not going to try your antenna when I have mine. to erect. Not many people put up to 50 foot towers? 140 feet apart. BTW I have a 3rd tower for VHF work. (6-2-440) All ready with homebrew yagi's. On 6 meters and 50 watts have worked Spain to South Korea from Kansas. Money aside, your environment may not dictate you wanting 2 towers. Like I don't have a $25K powerboat or golf.. There are hams that have only invested $30 into ham radio and golfers that spend $12K a year on golfing.? I am positive regarding? those that get into Amateur Radio then after a while loose interest; It is because they don't comprehend antenna basics, or get snookered into a MFJ ham-stick dipole, fed with LMR400 coax (because it's the best) or the flavor of the day... a EFW antenna with XX:1 Balun. All with Glowing reports stated to sell the rube these kind of antennas. If "crapo antennas" is not the #1 cause it contributes to those that try the hobby and leave... My goal,? as once was stated in the FCC part 97 rules and regulations is "to use Good engineering practices" ... This is particularly important with not only the growth but the continuation of the hobby. The opposite of "Good Engineering Practice" what ever it's called abounds today. Larry W8LM |
James Redding WA9VEZ
John D Erskine VE7MHI VA7OTC
John
MARSALE
Al WB9UVJ
Larry Macionski