Power suppy humm

I have build a power suppy using the transformer I bought recently.
The powersupply is now build in the 19 inch box.
It supplies 12V and 5 V.

It worked but unfortunately a lot of 50 Hz humm was present on the PLL synthesizer.
Shielding and decoupling did not make a difference. I was able to reduce humm by rotating the transformer 90 degrees. This helped lot but I an not satisfied yet. I should be moved away from the PLL as possible. I need some mounting things for this.

Power amplifier.
I build the 8 watt power amplifier in. It worked well unit I connected it to the low pass filter.
It starts oscillating when the 9.8 volt is supplied.
Another problem is the TX/RX relay. When I use I get only 4 Watt out .