Rebuilding the RF Step Attenuator

This is a total upgrade of the previous attenuator project, described here.
I wasn't happy with the response through the completed box, probably due to the inline attenuators and/or the switches.
On a local auction site I won an HP 0-70dB (10dB steps) step attenuator that came out of an HP spectrum analyzer.
Similar HP attenuators on eBay were quite expensive but I found an almost identical from Weinschel for a much better price. It is 0-11dB (1dB steps).
The two are so similar both in spes and appearance so one could suspect they came from the same manufacturer.
So now with these two I got a lot more variations of total attenuation so the old box could be given some more functionality. These are the changes:
Added two more selectable high scope settings (zero dB attenuation), 500mV/div and 1V/div so reference could be with SG5030 5Vpp at 1V/div (5 divs) or
3Vpp at 500mV/div (6 divs) and for CG 501x 1Vpp at 200mV/div (5 divs). The display had to be changed to four digits to show 1000mV/div at the 1V/div setting.
Other chnages were an added a function to select reset to either the lowest setting (as before) or the highest setting, a TEST mode function where each used single
attenuator setting is applied and could be checked with an VNA i.e. 2dB, 2x4dB, 10dB, 20dB and 40dB. In TEST mode the selected setting could be turned
on and off at a rate of approximately 2 Hz to clear contacts. The 12V power input connector had to be moved to the rear panel and a Power up delay was added
to ensure a proper start. The front panel power on switch and LED were moved down a bit.

Started with two high quality RF step attenuators in series.

Made two special circuit boards, one to decode the push buttons and control the switches and one to drive a 7-segments display. The control board is a total
redesign while the display driver is almost identical to the old but with a few changes to support the four digit display and now with SMD resistors on the copper
side so it could be made slightly smaller. The control board on the picture is the first version and some minor changes has been made on the final version and
two small boards were added.

Schematics here

The four digit display board. It uses a bright display chip from eBay.

The control & driver boards run at 5 VDC  and the attenuators require 24 VDC,  so in order to use a single common external 12 VDC adapter the voltages had
to be generated using a step down converter and a step up converter. These come very cheap from eBay or Ali Express and work fine.

The boards installed in the case.

I used push button switches from a scrapped 2430.

The front panel from the inside ....

.... and from the outside.

The almost finished inside of the box from the rear ....

... from the side ...

.

... and from the front.
The extra board on top left is the power up delay and the extra board under the N-connector is the exerciser board which provides clock to turn the attenuator
off and on when a push button swithch is pushed in TEST mode.

The rear panel. I used an N-connector instead of SMA to increase the mechanical stability since here is where the CG or SG head will connect.
The toggle switch selects either NORMAL or TEST modes and the push switch enable toggling the attenuator settings ON/OFF while in TETS mode.

The finished box.

Email me with comments. /Håkan