- solidifying toroid core position and windings? - 2 Updates
- Calibration procedure of HEATHKIT IM-2202 - 1 Update
| amdx <amdx@knology.net>: Feb 11 03:37PM -0600 On 2/10/2022 3:54 AM, Jake T wrote: > quick, easy, and effective solution. I wouldn't think the clear, two > part epoxy would affect Q or tuning, or would it? > Thank you! I have used polystyrene dissolved in Acetone. Best if you can find crystal styrene like used in parts drawers. It will dissolve... slowly. But I started with polystyrene foam dissolved in acetone. I have a 4" coil I used this on well over 10 years ago and it it still holding up. Mikek -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
| Jeff Liebermann <jeffl@cruzio.com>: Feb 11 08:08PM -0800 On Thu, 10 Feb 2022 04:54:15 -0500, Jake T <jaketbone@steak.com> wrote: >easy, and effective solution. I wouldn't think the clear, two part >epoxy would affect Q or tuning, or would it? >Thank you! If your toroidal inductors are wound that loose, you'll have damage in shipping, mostly from the enamel coating falling off from vibration. Some kind of conformal coating will help. <https://www.chemtronics.com/the-ultimate-guide-to-conformal-coating> Before selecting any coating, lookup the loss tangent values and see if it will get hot due to RF losses. If you're not sure, coat a PCB with the coating, let it dry, and bake it in a microwave oven. If it tends to crumble, burn, melt, or otherwise self destruct, find something with less loss. 1kW at 2.4GHz is a rather brutal test for a coating that only needs to work up to 30MHz, but is quick and easy. If it survives at 2.4GHz, it will work at 30MHz. If the BP filter is designed using high Q inductors and mechanical vibration detunes these inductors, your design is faulty and you will have other problems, such as multiple problems caused by water. I used to design marine radios and quickly learned that high-impedances, high-Q tuned circuits, and high voltages were really bad ideas in a marine environment. So, we designed most everything using low impedances, low-Q tuned circuits, and low voltages. The result was that the radio worked nicely when wet and did not require any kind of coating. Such coatings are a mess to apply and handle. Rework is either difficult or impossible. Here's an example from about 1980. This is the Intech Inc Mariner 3600 150w PEP SSB HF marine radio: <https://ce3dr.files.wordpress.com/2016/12/img_1630.jpg> <https://ce3dr.files.wordpress.com/2016/12/img_1631.jpg> <https://ce3dr.files.wordpress.com/2016/12/img_1632.jpg> <https://www.hellocq.net/forum/read.php?tid=226493> The large board full of toroidal inductors are the TX/RX LP (low pass) filters. We didn't use or need BP (band pass) filters. Notice the lack of any conformal coating. I will admit that we did use some wax to keep the synthesizer VCO from becoming microphonic. It was also one of the few circuits that were sensitive to moisture. Good luck. -- Jeff Liebermann jeffl@cruzio.com PO Box 272 http://www.LearnByDestroying.com Ben Lomond CA 95005-0272 Skype: JeffLiebermann AE6KS 831-336-2558 |
| "Peter W." <peterwieck33@gmail.com>: Feb 11 08:48AM -0800 https://www.youtube.com/watch?v=EL3zzosjQ0c https://elektrotanya.com/heathkit_im-2202_portable_dmm_sm.pdf/download.html Should about do it. Enjoy! Peter Wieck Melrose Park, PA |
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