Hi Fabio,
I'm going through the same 7A13 repair as you are. My Tek relays are failing and three rotors have fallen out of the air-variable input tuning caps.
I chose the Fujitsu NA12W-K as my replacement relay and decided to replace them all. The Fujitsu is rated at 220 VDC and has good specs
at 100MHz. I made a pcb adapter board to simplify the wiring. Only two different pcb patterns were needed to satisfy all of the Tek relay pin-outs.
I included an SMT full wave bridge on the pcb to convert the Fujitsu relays to non-polarity coil types. I've replaced all relays and the four input
attenuator variable caps. The DC offset and gain calibration has gone well. I am partially done with the RF cal and so far, the 3dB BW has been
good to 100MHz using a 50 Ohm source.
My concern now is BW performance when the input attenuators are in operation. I have taken capacitance measurements of the Tek, Fujitsu,
and Omron G6K relays. They all measure about the same when separate. When I mount the Fujitsu relay to the adapter board, the capacitance
between the armature to the open contact jumps from 0.3pF to about 1.7pF. The pcb adapter adds roughly 1.3pF to all four inter-electrode
points I've measured. I'm using a DE-5000 LCR meter @100KHz. I have pics of my progress so far if anyone has an interest.
Thanks,
Tom Ford
