Antenna Box #5

This is the page for the first box to use the new antenna.

A identical prompt was put to both Gemini and ChatGPT for the basic design of this box. It started with an RG58 input, a banana post output and a rotary switch selecting 5 different toroid matching coils with the first coil doing double duty for bands 1 and 2.

The ChatGPT exercise was a dismal failure on many counts:

• You can's save the page as an HTML document. I was using Brave and Firefox and got the same result
• You can't print the conversation. I tried and it looked like I was going to get 60 pages but they were all blank
• You can't print to a file
• There is an option to print to a PDF file. It only does the 1st prompt and response and then 50 something blank pages
• You can't search for a word on the page
• You can't cut n paste from the page
• The 'conversation' wandered all over the map. At one point, ChatGPT wanted to create a comprehensive engineering grade document containing everything there is to know about the SX-28 using the sx28.info website as a reference
• There were a lot of times where it said "I am going to do this" and when told to do that, repeated what it was going to do in different words. Sometimes, when it did do it, it was only a page that outlined 'this'.

One of ChatGPT's final comments was, and I quote:

        I agree they are serious limitations for someone doing technical work.
        If I were writing an engineering notebook, I'd expect to be able to:
            • ✓ Search for "FT-82-43"
            • ✓ Print the conversation
            • ✓ Save it as PDF
            • ✓ Export as Markdown
            • ✓ Export as DOCX
            • ✓ Copy large sections
        Those are normal expectations for technical documentation.
        The fact that you're hitting problems with all of those makes
        ChatGPT much less useful as an engineering notebook than it ought to be.
    

Gemini did a much better job and that is what is used as a reference for this page. If your're really bored, you can download a LibreOffice Writer document for Gemini and ChatGPT dialogs:     Gemini     ChatGPT

I'm finished with the AI stuff, I promise. But since the prompt I used spells out what the box is, I might as well use it with just a few tweeks.

        I intend to build an antenna that consists of a 57 foot long 16 AWG insulated
        wire, a 9:1 unun balun, a 50 ohm RG58 cable that is 33 feet long with PL-258
        connectors on each end.

        I have a plastic adapter box. The box has a SO-239 (accepts the PL-258) connector
        on one end and a pair of banana jacks on the other.

        The antenna RG58 cable connects to the box and the banana plugs connect to a
        Hallicrafters SX-28 receiver with a 400 ohm antenna input. The connection to
        the receiver is via 18 AWG stranded wire to the A1 and A2 receiver terminals.
        Neither terminal is connected to the receiver's ground terminal.

        The SX-28 has 6 bands. The six band frequencies are (6) 21-43 MHz,
        (5) 11-21 Mhz, (4) 5.8-11 MHz, (3) 3-5.8 MHz, (2) 1.6-3 MHz and
        (1) .55-1.6 MHz.

        The box has a 5 position 6 pole rotary switch that connects the input to one
        of five toroid matching transformers, one transformer for each band with the
        exception that the two lower bands (1 and 2) use the same matching transformer.

        I have FT-82-61 and FT-82-43 ferrrite cores on hand. I have 20 AWG and
        28 AWG enamel insulated wire on hand.

        I need very detailed instructions on how to wind the cores.
    

What I got from this request was two slightly different tables telling me how many turns of wire to put on the five toroids.

Page: /Antenna_box_6/Antenna_box_6.shtml

Last modified: Friday, 7 Aug 2026