Re: Radiated EMI from displays
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If you make one for the 7" display, put me down for one. Jack, W8TEE
On Tuesday, April 8, 2025 at 01:58:13 PM EDT, K9HZ <bill@...> wrote:
I finally got my 4-axis CNC machine fired up last night and the first thing it made was a box for the back of my radio with a 5¡± display based on John Lundberg¡¯s work.? I¡¯m pretty excited about this even though it turned out to be a disaster (idiot G-coder me)¡ but it was a step forward.? I have buckets full of scrap PCB to work from to work with to get this right¡ ?but my rather crude test measurements confirm Terrance¡¯s assertion that it is, indeed, worth about 20 db noise floor reduction on the upper bands to placing the entire display into a shielded box. ? I have a young hot-shot engineer that started working for my engineering consulting company this week¡ and I think I will put him on this project¡ to get him up to speed with our lab.? I¡¯d rather work on the 100W amp getting those kitted and finalize the Auto Tuner.? [BTW, anyone want to work along with us to see how that project comes together? I¡¯ll start a #Tuner thread for it]. ? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ VP2EHZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: ? Moderator: North American QRO Group at Groups.IO. Moderator: Amateur Radio Builders Group at Groups.IO. ? email:? bill@... ? ? From: [email protected] <[email protected]> On Behalf Of Terrance Robertson, KN6ZDE via groups.io
Sent: Thursday, March 27, 2025 5:11 PM To: [email protected] Subject: Re: [SoftwareControlledHamRadio] Radiated EMI from displays ? Another way to test this is to disconnect the display altogether.? This can't be done with the existing software as the code will hang trying to start the RA8875 object.? However, in developing the T41 Beacon Monitor, I created a version of the T41 software that doesn't update the display, though the RA8875 object was still there to display the Beacon Monitor.? With a bit of work, I separated that portion of the display code as well.? I can now completely disconnect the display.? It's not too hard to print the S-meter value to the serial monitor, but controlling the radio without a display is a bit of a guess.? That's where my comes in handy.? With that I see a 10 to 20 dB reduction in the noise floor on the upper bands of the 4SQRP without its 5" display.? This seems consistent with the results that John posted. ? I need to repeat this with my v12. ?? -- Jack, W8TEE |
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