04-10-2025, 01:43 PM
David - I think I understand but what units are you discussing (Low of 1.7, high of 3.9)?
Budget constraints for Ham Radio led me to a 25A power supply that is a switching design. The reviews were good, and I have found it to be almost perfectly quiet. It does have the odd harmonic audible on the lower bands, but very feint, and the PSU has an adjustment that allows you to shift the frequency to remove the interference. So far it has been great.
One of the worst offenders for QRN here are two items on my test bench - my soldering iron, which must have some really cheap triac temperature adjustment circuitry, and my digital signal generator, which spews out digital harmonics all over the place, and can make some adjustments difficult - in which case I bring out the old Heathkit tube generator. Should really go through the caps on that LOL!
On the Zenith, just waiting for my shipment of NE51 pilot bulbs, then it can all go back together.
Budget constraints for Ham Radio led me to a 25A power supply that is a switching design. The reviews were good, and I have found it to be almost perfectly quiet. It does have the odd harmonic audible on the lower bands, but very feint, and the PSU has an adjustment that allows you to shift the frequency to remove the interference. So far it has been great.
One of the worst offenders for QRN here are two items on my test bench - my soldering iron, which must have some really cheap triac temperature adjustment circuitry, and my digital signal generator, which spews out digital harmonics all over the place, and can make some adjustments difficult - in which case I bring out the old Heathkit tube generator. Should really go through the caps on that LOL!
On the Zenith, just waiting for my shipment of NE51 pilot bulbs, then it can all go back together.
I don't hold with furniture that talks.
![[-]](https://philcoradio.com/phorum/images/bootbb/collapse.png "[-]")
