Nice trepanning job, I have done that on medium format camera lens adaptors.
I had a failure of the little HF 30 T c/t here. I might be lucky it was not on my new 'scope!. The old Eico 410 10 Mhz survived.
The attenuator is ~ 4:1
Previously:
R11=R22 = 50 Ohm 1 watt precision
R21=R12 = 120 ohm 1/4 Watt.
I had the c/t on primary of inverter transformer
When the inverter started into low load, the transformer momentarily saturated ( separate problem)
Resistor R11 blew to pieces and started arcing due to the higher resistance (290 Ohm) seen by c/t
So I changed to
R11 = 56 Ohm 3 Watt paralleled with 470 Ohm to get near 50 Ohm
R22 still 1 Watt precision but with but added paralleled back to back zeners 4.7 V 1 Watt .
I will make a board for that with a semicircle to glue the ferrite core and bnc onto.
I am using these as pre-wound c/t, need to get some more @ $0.50 ea
Don't know what the core is and they work as transformers up to 100 MHz, I used one as UnBal for the FM broadcast receiver
https://www.surplusshed.com/pages/item/M2199.htmlEdit: ordering some of these for the burden/attenuator:
CGS 355051RFT
SMD Chip Resistor, 51 ohm, ± 1%, 5 W, 4320 [11050 Metric], Thick Film, High Power
Max 300 V rated working 111 Volt
Maybe that size not necessary for RF use