Railroad Spectra

[arlojanis]

A railroad brought me a Railroad Spectra and said it runs the battery down. I hooked it up on 12 volt pins and radio checks all OK. Standby current is 1 amp and receiving audio is 1.75 amp. Do you think it is a radio problem?

[motorola_otaku]

Did they specify whether it was being powered on the 12V side or the 72V side? There could be a problem with the 72V regulator that might not manifest itself on the 12V side.

[arlojanis]

I have not asked about input voltage yet. My bench supply only goes up to 40 volts. Do you think 40 volts will start the 72 volt supply?

[motorola_otaku]

Probably not. Time to wire up some car batteries in series.

[k2hz]

I have not asked about input voltage yet. My bench supply only goes up to 40 volts. Do you think 40 volts will start the 72 volt supply?

I just tried a RR Spectra on my bench and it will start as low as about 36 V. Below that it tries to start but acts flaky. I assume if I tried to TX it would need normal voltage but it will power up and RX at 40V.

But, If you get it to start at 40V and it looks normal it does not necessarily mean it won't fail at normal working voltage.

I am curious about what the real problem is. Since there is no on/off switch on the radio it needs an external switch unless they just depend on it going off when they pull the main switch. I have seen some locos where the radio power is off a breaker that intentionally is directly to the battery so the radio can be used even if the loco is dead.

If this is the case, you will have a dead battery if the radio is left on and the loco is not run for many days.

If the radio looks OK, some older locomotives had a WABCO surge surpressor in series with the radio power that could develop leaky caps.

I am always suspicious of a mechanic claiming the radio "runs the battery down". It usually turns out to be a battery that is about to fail or a charging system problem.