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Indeed, contrary to my expectations, it did virtually nothing to suppress RFI. I made the plates from a stainless steel solder paste stencil, ordered from JLCPCB. See the attached picture. I carefully cut out the plates with household scissors under a microscope, so that all the teeth were the same length.What did help was the combination of a ferrite bead in the Drain output, a GND ferrite bead, X2Y cap between pins 2 and 3 to XLR pin 1 GND and two more ferrite beads between X2Y cap and the transformer. Beads and X2Y cap are SMT parts, btw. There was no space between transformer and XLR connector for a Common Mode choke à la CM-63, but an X2Y cap works satisfactorily, provided you've got a good (or good enough) ground plane connected to the shell. This, I established using the same XLR insert as used in the Takstar CM-63, with a low impedance ground pin to the shell. I found those on Aliexpress here: https://www.aliexpress.us/item/32948607190.html?spm=a2g0o.order_list.order_list_main.5.75c879d2obEJKZ&gatewayAdapt=4itemAdaptJan[ATTACH=full]133192[/ATTACH][ATTACH=full]133193[/ATTACH]
Indeed, contrary to my expectations, it did virtually nothing to suppress RFI. I made the plates from a stainless steel solder paste stencil, ordered from JLCPCB. See the attached picture. I carefully cut out the plates with household scissors under a microscope, so that all the teeth were the same length.
What did help was the combination of a ferrite bead in the Drain output, a GND ferrite bead, X2Y cap between pins 2 and 3 to XLR pin 1 GND and two more ferrite beads between X2Y cap and the transformer. Beads and X2Y cap are SMT parts, btw. There was no space between transformer and XLR connector for a Common Mode choke à la CM-63, but an X2Y cap works satisfactorily, provided you've got a good (or good enough) ground plane connected to the shell. This, I established using the same XLR insert as used in the Takstar CM-63, with a low impedance ground pin to the shell. I found those on Aliexpress here:
https://www.aliexpress.us/item/32948607190.html?spm=a2g0o.order_list.order_list_main.5.75c879d2obEJKZ&gatewayAdapt=4itemAdapt
Jan
[ATTACH=full]133192[/ATTACH]
[ATTACH=full]133193[/ATTACH]
