If you aren’t familiar with VHF/UHF repeater operation, now is a good time to review it here. Repeaters are frequently used for chatting with local hams, regular nets, and EmComm use.
An occasional problem with repeater operation is when a weak transmitter doesn’t have enough power to keep the repeater’s squelch open. That is, you can tell someone is there but hear little or no signal. Could be that the transmitter is in a sheltered location, doesn’t have a good antenna, or using too little power.
For whatever reason, they can’t break through with a strong enough signal to be heard. If you suspect this is happening, you can try listening to them directly instead of through the repeater. It’s possible that you are closer to the weak transmitter than the repeater is.
Many hand-held radios (HTs) and mobile VHF/UHF transceivers support this with a repeater reverse function, typically by pushing a button on the radio.
Recall that a repeater re-transmits what it hears on a different frequency. The difference in transmit and receive frequencies is called repeater offset and this minimal difference is needed to allow for sharp filtering between them so that the strong transmit signal doesn’t damage sensitive receiver circuitry.
By selecting reverse on a transceiver you then listen to the repeater input frequency instead of its output. In this manner you can get the weak transmitter’s true signal strength and quality, not what the repeater re-transmits. This assumes that you are receiving better than the repeater, which is a possibility but not a certainty.
Useful when you want to see if a weak signal is attempting to get into a repeater. Even if they can’t get through, a net control operator (or you) can tell them what’s going on since it’s likely they can hear the repeater. In an emergency, somebody on the net might be able to copy them on reverse and relay their info.
This exam question is somewhat misleading; the term “reverse split” doesn’t really apply to transceivers. Reverse split has a valid meaning for older repeater systems in highly-populated areas where coordination was an issue. “Reverse split-frequency” is valid for transceivers and more appropriate phrasing.
Note that reverse should be used only briefly to monitor the repeater input frequency. If you transmit while in reverse you would be competing with the repeater’s output.
Split-frequency operation is a function of most modern transceivers. It permits the radio to be set for different receive and transmit frequencies by having two variable frequency oscillators (VFOs). Commonly called split mode where the two VFOs are on different frequencies.
Split mode is required for repeater operation; it is native to practically all VHF/UHF FM transceivers.
On HF transceivers split mode is used similarly without the fixed offset frequencies (pairs). Here the two frequencies are variably set and are commonly used by contesters or rare DX stations to help sort out the pileup of stations eager to reach them. It takes some skill and experience to use split on HF bands. A relevant link is found here, which also provides an excellent reference for the other topics in this post (repeater offset, simplex and duplex modes).
Repeater reverse is just another weapon in our arsenal. Consult your own radio manual(s) for instructions on how to select the reverse function.