Here's some info on what one of our members Bob DeGuarde built. We also built a 455khz signal booster/filter based on plans found on the TMCC Google Groups site.
455kHz Earth Ground Signal Strength Meter - To check the signal strength which the TMCC/Legacy engines radio receives, we built a 455Khz earth ground signal strength meter that consists of a Lionel R2LC radio board and an additional capacitor & resistor. On the R2LC radio board, I soldered a wire to pin 13 of the MC3372 IC, which is located on the R2LC board. Pin 13 provides an RSSI output signal reading. See the page 11 & 12 of the spec sheet for the MC3372 IC for further details for a RSSI connection. Power, multi-meter and antenna connections to the R2LC board are outlined in the attachments below.
The earth ground signal meter allowed us to obtain signal strength readings around our layout and showed us the areas where we need to improve earth ground signal. We first took readings on a small 4’x8’ test track, so we knew what an ideal reading should be. On our test track, we obtained signal strength readings in the 45-49ua range. When taking readings on the club’s layout, we originally obtained readings of upper 20 ua to high 30 ua range. We used a Harbor Freight multi meter on the micro amp range to get our readings. Some ways to increase the amount of earth ground signal to the engines radio is to add earth ground wires on the layout and or increase the size of the engines antenna. Where it was practical we did both of these items and were now able to obtain readings into the high 30’s to mid 40’s ua for most of the layout. We eliminated the vast majority of engine non-responsiveness (blinking head light) when we were able to obtain signal readings in the low 40 ua range.
If you are extending the antenna of an engine, 3M makes 1/2” self stick copper foil which works out real well to improve signal reception. Google “3M copper foil” for 20’ roles.
Thanks to OGR forum member Gary Emmich for investigating on how to use the R2LC radio board to measure signal strength
