Question on 2nd TDI SL mod as suggested by Reg Sniff...

[Jim in Idaho]

I'm a TDI SL owner. I recently did the Sweep Speed mod of swapping out C20 & 21. I'm now considering a mod suggested by Reg Sniff to do away with D20, and C56, and put a jumper across D21. Apparently this is something White's changed, possibly in 2015. (my unit is a 2013) I know the new TDI Special Edition has this change. My question is what does this modification accomplish? I'm an old, with the emphasis on old, radar tech, and I'm not sure I want to tackle these tiny parts unless it's going to make a significant difference in performance of my machine. I really enjoy the results of the sweep speed mod. Any light you can shed on this would be gratefully received.
Jim

[Carl-NC]

Removing C56 is recommended. It was added to reduce ground chatter but in reality it can hurt performance.

D20 & D21 are part of the original changes that Reg came up with during the SL redesign. They are part of the target channel, and there are similar diodes in the ground channel (D18 & D1. The original TDI did not have these, and they help reduce ground noise. I'm not entirely sure what will happen if you remove them from the target channel but not the ground channel. This is where input from other people might help.

[Orbit]

I think on some versions the target channel have not set but I would say they influence to reduce noise and on the target channel when removed, a greater range of detection is obtained but also more noise !

[KingJL]

... I'm an old, with the emphasis on old, radar tech...

That's where I started... 1961 thru 1979.

[Jim in Idaho]

That's where I started... 1961 thru 1979.

Yup...I was Air Force '68-'72. San Antonio, Biloxi, San Bernardino, and Chandler, AZ.
Jim