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April 10.2024. T S Eliot once wrote April is the cruelest month. It might be about paying income taxes.

I received two comments about power inverter switching noise and my choice for the Mean Well DC to DC. [Five Days to April 15th.]

Energizing the Mean Well you do not hear any consistent hash noise in the SDR. But I did note after a short while you would hear a random noise for a short while and then it would move on. During one of those noise events, I unplugged the Mean Well power supply, and the noise went away. Later I had a chance to repeat that event and the same outcome. I can best describe it like a random oscillation. The switching frequency of the Mean Well is 150kHz.

The following You Tube documents the unscientific test.


 

So, likely the Mean Well would be objectionable for use "as is" without addressing the observed condition. What we have is a SOB (Sneaky Oscillation on Board). This may be a tough nut to crack! 

If it were a consistent and constant Hash Noise, then perhaps large choke values and large value capacitors could filter those from the DC output. The Mean Well is encapsulated and no way to access the innards to abate what appears to be a random oscillation that manifests itself as a noise burst. 

I have a bench supply good to 30VDC @ 5 amps. I ran a quick test and observed even more output from the IRF510 enough so to drive the SB 200 to 200 watts out. It was late and I did not have time to evaluate any Random Noise from this supply. 

But certainly, from my less than rigorous tests there is an argument to run the IRF510 with something larger than 12VDC. That said there is a significant technical argument that unless you had sufficient drive, increasing the voltage to 24 or 28VDC bought you nothing. 

My "unwashed tests" indicate there is sufficient drive from the 2N2219A present to give your signal a big boost. The RF Chain is the same as in my non-conventional PSSST-20 SSB Transceiver found at https://www.n6qw.com

There are no contests or operating tips involved --just some quickie homebrew testing.

Now for some TKT (Tribal Knowledge Tips). Realizing heat would be involved, the standard TO-220 small heat sink was not a good choice for testing the IRF510 at higher power. Thus, a homebrew fabrication using a U-Shaped thick web aluminum channel. That jewel is about 1 inch wide and 3 inches long. 

After running a series of tests at 30vdc I tested the efficacy of the homebrew heat sink by placing my thumb on the sink. While plenty hot I did not burn my thumb nor smoke the IRF510. Test Successful! Incidentally, I used a lot of ferrite chokes on the open HB SDR that snap on and that Ferrite core is on the bias line to the IRF510. 



Cross Section U Channel

Yes, you likely did two things: (1) you checked Amazon for the U Channel and (2) then crapped your pants at the cost. Try eBay.


73's
Pete N6QW

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