Yes, that's the correct way. I have never built a crystal set with a tuning coil and a tuned loop. Usually the tuned loop functions as the tuning coil. On my superhet shortwave sets, I wind a tuned loop and then a separate "coupling" loop that attaches to the radio terminals. https://2.bp.blogspot.com/-IOhUPBl29yo/VlWR-K34bGI/AAAAAAAAFQ8/yjnaCQCrA0M/s1600/untitled.JPG The "induction" designs work well with the old AM transistor pocket radios, You just bring the radio inside the loop and it couples to the internal antenna in the radio. It may work with your design if you put your "board" close to the loop, ideally inside the loop.

Beautiful work, but it's not a typical "loop" antenna as normally used with simple radios. Your antenna seems to have only one connection, so it's just a random length of wire wound in a beautiful pattern. To work effectively, it needs two wires to the radio to be a tuned loop. This site has lots of good ideas, including using an LM386 amplifier to get around the complexities of piezo earpieces. https://www.electronicsforu.com/wp-contents/uploads/2021/06/14-500x301.jpg I have built crystal sets and loops and am amazed by the performance of tuned loops. I use quilting hoops as my forms. https://antiqueradios.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=155149&g2_serialNumber=2 It can be frustrating trying to copy a primitive design, so I use all the modern "aids" that I can (like audio transformers or LM386 amps) to get it working, then gradually change things to duplicate the intended simple design. Rich

Thanks, lots of useful info. Just need to remember the voltage limitations of the various junctions. Rich

The new Chinese dials are intended for use with potentiometers, which are usually 270 degrees. Almost no one uses variable capacitors these days, so no market for 180 deg. dials. I bought a couple of these; well made. Haven't used one yet but will be great for my small transistor regens and superhets where I tune with a varicap diode and pot. Rich

My EE career started with Alfred Morgan... crystal sets, triodes, etc. That got me into ham radio. Wanted to know more about why things worked, so got a BSEE. Morgan is my hero. Rich

An electric car with a 50 hp motor is basically a 50 KW RFI source. The drive electronics operate at 50 or 100 KHz, so harmonics and junk in the AM band are pretty much inevitable. The motor can be shielded and the drive electronics can be "tailored" to reduce RFI, but many car builders are asking "why?" AM is not a big market any more, especially for young people. There are reasons to keep AM, like emergency warnings, but the engineering effort and cost are not trivial. Lots of discussion about this recently on the Antique Radio Forum. Rich https://www.antiqueradios.com/forums/viewtopic.php?f=2&t=426541

Here is a link to typical polyvaricon capacitor. https://aucklandvhf.org/product/2-gang-45-130pf-miniature-polyvaricon-for-am-fm/

They are trimmer capacitors and part of the tuning capacitor. Rich

Why do you want a bleeder? To discharge the filter caps when the supply is OFF? The Zener string is already conducting at least 10 mA (see data sheet) and will discharge the caps (eventually). If the desired discharge time is really 0.05 seconds, you don't need a big resistor. 2 Watts should be fine. Rich PS: 250 ohms is way too low. It will draw 400 mA steady state at 100V output. This kind of circuit is intended for radios that draw under 50 mA steady state.

Radio experimenters have been using plug-in coils for many years. Whether a tube radio or crystal, the coil calculations are the same (a tube radio will often have an extra winding for feedback (regeneration). http://onetuberadio.com/2016/02/12/making-your-own-plug-in-coils/ Rich

I think the on-line calculators are easier. https://www.crystalradio.net/professorcoyle/index.shtml Lots of good crystal radio resources on this site. Rich

You will probably get more "views" and help on AntiqueRadioForum. ARF is more focused on restoration and repair of tube radios. https://www.antiqueradios.com/forums/viewforum.php?f=6 Rich

https://web.archive.org/web/20200714035210/http://makearadio.com/misc-stuff/capacitors.php Years back, Dave Schmarder had a nice write-up about variable caps and plate shapes. Rich

Thanks for inserting my schematic. Rich

https://antiqueradios.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=157693&g2_serialNumber=2 Don't know how to display this image? Rich

About 20 yrs ago, I bought a "one IC radio kit" from Dick Smith Electronics while I was in Australia. It turned out to be a crystal set using a CMOS IC CD4007, as a chain of audio amplifiers. I'll try to find a circuit diagram. Worked surprisingly well even up to 5 MHz shortwave. Rich

1. Center punch your holes 2. Buy a center drill. It's a drill with a point that's almost a needle, with a thicker shank to prevent wobble. If that doesn't work, you may need a new drill press. https://m.media-amazon.com/images/I/31O4zHQUseL._AC_UL480_QL65_.jpg

I use COREL DRAW for panel templates. Since I usually use aluminum or opaque acrylic, I tape the paper template on top of the panel and mark all the holes with a punch. No parallax if the paper is on top of the plastic. Rich

NEVER mind! I figured out how to do it... very easy. Rich

Unfortunately, much of Dave Schmarder's work is hard to find now that Make A Radio is gone. He did some nice work with 1625s and other large tubes. https://www.antiqueradios.com/forums/viewtopic.php?t=86155 Rich