As part of my work with Lyle Dumont in Iowa to solve his TMCC signal problems, I developed an easy technique to measure the strength of the TMCC/Legacy signal going to the track (http://www.trainfacts.com/trainfacts/?p=436).
Recently Lyle made some measurements on his 2 layouts using my newly-developed measurement kit that were very interesting. First, he measured the Legacy base on his big layout (50’x90′) without anything except the metering circuit connected to the Track stud and Pin 5 of the 9-pin serial port. He got about 1 volt, which is only half of what he should get for a good Base. (Interestingly, when I visited Lyle over a year ago with my oscilloscope, I found his Legacy Base was defective, clipping off half of the sinewave Track signal. He sent it to Lionel for repair, but now I doubt that it was ever really repaired since his voltage reading agrees with a half-clipped sinewave output.)
Lyle then connected the Track wire to the stud, and the signal dropped to about .3V. We expect to see a lot of capacitive loading with a large layout and we don’t have any numbers that determine go/no go for the Track signal.
Next, Lyle brought the Legacy Base from his smaller layout onto the big layout. The unloaded reading was the full 2 volts that is expected, and the loading dropped things to about .63 volts, twice what the other Base was outputting. He was able to run his balky steam engines without problems using the good Base.
Lyle was also able to make signal measurements on the smaller layout to confirm that he was getting a stronger Track signal, which was to be expected with the reduced capacitance of the smaller layout.
Using the meter, Lyle was then able to determine that some coax cable feeders that he had added a while back were actually degrading the output signal. When he removed the coax, the Track signal increased more than 25%.
The moral of this story is that you can’t beat having something that quantitatively measures the actual Track signal. As a result, I am going back into the “TMCC/Legacy accessories” business by offering a complete metering unit.
The kit includes a rectifier unit that conditions the Track signal, a digital volt/ohm meter for reading the signal strength, and the proper wiring and connectors (feed-through 9-pin and forked lug) for attaching to a TMCC or Legacy Base. The package includes a 5-page operating manual with troubleshooting suggestions for several types of signal problems. The digital meter can also be used to measure resistances and AC voltages during troubleshooting/testing.
The feedthrough 9-pin allows the metering system to remain connected during normal layout operation. This connector also has a 6’ breakout wire connected to Pin 5, the “earth ground” point on the Command Base that can be used as the starting point for earth ground signal enhancement wires.
NOTE: This device does not measure the airborne signal strength at an arbitrary point.
The price is $60 plus $7 Priority Mail shipping. California residents add $4.50 (7.5%) sales tax. Payment via check (preferred); PayPal, Visa or MasterCard add $2 processing fee. Contact me at firstname.lastname@example.org or (805) 529-2496 for more details or to place an order.