Re: Large heatsinks on a ubitx v6


 

Barry,

Ground the heatsink to chassis or circuit ground and that will prevent radiation of RF into the internal circuit and wires.

Raj

At 28/04/2020, you wrote:
Greeting. Someone might have an answer for this issue I am having with my V6 ubitx. I installed large (massive) heatsinks on the two final irf510's. I used mica TO220 mounting insulators, etc.
Unfortunately, now the radio goes spastic above 5 watts on 80 meters. It happens on all band and gets worse on higher bands. The wave form is distorted and looks more like a pulsed sign wave. I suspect rf feed back, but where. I am using a dummy load, not any antenna.
Looking over the schematic, I see feed back resistors from the drains to the gate but no capacitor. I was wondering if a small cap was installed would this help? Has anyone been down this road?
Thanks
Barry
K3BO

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