I asked this question originally. As an update, I just finished installing a LocoFi-3 module, with a TCS KA-4 keep-alive, in a brass Lambert Models HOn3 Rio Grande Southern three truck Galloping Goose. It all just fit inside the shell, and it works fine with no signal problems even though the only opening into the brass shell is a roughly 5/8” x 1 1/4” hole in the bottom for the metal power truck, which then fills most of the opening.
Electrical pickup on these models is not very good and is difficult to improve, but adding the Loco-Fi plus a keep-alive appears so far to have led to very solid, reliable operation.
It was a quiet day in suburbia so I hooked up a couple just to see if I could connect them without anything burning up or exploding.
This worked out fine with separate tests of CurrentKeeper only and No Halt Insurance only. This confirmed that the blue wire on both was positive and the black (or black/white) wire was negative.
The voltages on each (measured at the + and - outputs of the bridge rectifier) were slightly different but not enough to matter:
Start: 10.75 VDC
At the end of 5 minutes: 11.25 VDC.
Track power* was disconnected at 5 minutes.
5 minutes, 30 seconds: 10.5 VDC
10 minutes: 9 VDC
* 12 VDC, 1 A "clean" wall wart
Tomorrow, I'll try adding a DULLHB to the + and - terminals of the bridge rectifier
I asked this question originally. As an update, I just finished installing a LocoFi-3 module, with a TCS KA-4 keep-alive, in a brass Lambert Models HOn3 Rio Grande Southern three truck Galloping Goose. It all just fit inside the shell, and it works fine with no signal problems even though the only opening into the brass shell is a roughly 5/8” x 1 1/4” hole in the bottom for the metal power truck, which then fills most of the opening.
Electrical pickup on these models is not very good and is difficult to improve, but adding the Loco-Fi plus a keep-alive appears so far to have led to very solid, reliable operation.