The most common crossbanding scenario is to have an HT programmed to xmit/receive on a 440 MHz simplex frequency to a CBR. The CBR receives the HT’s signal on 440 MHz simplex and instantly rebroadcasts, or repeats, the audio on 2-Meters, usually to a distant repeater. When the CBR receives a signal on the 2-Meter frequency it is repeated on the 440 MHz simplex frequency to the HT. It is possible to reverse the above scenario and use a 2-Meter simplex frequency locally to repeat to a distant 440 MHz station, but finding a clear 2-Meter simplex frequency is often difficult, especially during events or in urban areas.

Crossband Topics – (Easy to master once you’ve done them a few times.)

1. Station Control & ID – Regardless of whether your CBR is in a vehicle, set up as a fixed base, or portable in a backpack, you must be able to control the “remote station” to ensure that it operates properly. [FCC Parts 97-105, 97-109.] Also, you must be able to ID the transmitter on all frequencies, which is not always an easy task for the downlink side (CBR to HT). [FCC Part 97-119.] Some CBR manufacturers have included an automatic repeater ID function.
   
2. Follow good amateur radio practices. Always try to obtain permission from a repeater owner before setting up your CBR to access a distant repeater. Some owners frown on it because of interference from accidental signals getting into the CBR resulting in lots of unidentified ker-chunks on their repeater.
3. Simplex Frequency Selection – Many frequency coordinators have already designated a group of frequencies to use for the simplex side of your CBR. In our area, the South East Repeater Assn. [SERA] has 12 simplex 440 MHz frequencies for a FIXED BASE repeater and 12 simplex 445 MHz frequencies for a MOBILE repeater. There are no 2-Meter frequencies designated for crossband use. I chose 440.8625 for BASE use and 445.8625 for MOBILE use. I have these programmed in my HT’s and CBR for a quick setup.   
4. Note: SERA’s 440 MHz Frequency Use Plan can be downloaded from SERA.
   
5. Tone Squelch on Simplex Frequency – It is strongly recommended to use a Tone Squelch or Digital Coded Squelch on the UHF link frequency to minimize unwanted signals from getting into the CBR and any other repeater downline. I chose 192.8 Hz for my tone squelch. 
   
6. One-Way vs. Two-Way Crossband – One-way crossbanding is when you use the CBR to repeat only one side of the traffic. It requires the use of a dual-band HT. For example: Your HT can hear a distant 2-meter repeater but cannot transmit to it. You program the HT with an ‘odd split’ to transmit on 440 simplex (to the CBR) and receive the 2-meter repeater’s output direct. The CBR only repeats the HT transmission to the 2-meter repeater and sits idle when the 2-meter repeater is active. Two-way crossbanding is where the CBR always repeats a signal received on one side to the other side and vice-versa. For two-way crossbanding, a mono-band HT can be used on the simplex side. 
   
7. Repeater Settings – These steps will vary by make & model, but for me the easiest thing is to set up a small checklist with all the settings that I’ll need. This includes the 440 simplex frequency & tone for the ‘local’ side of the CBR as well as the frequency, offset, tone for the ‘distant’ side of the CBR. Once the settings are complete, there is usually a specific series of key presses on the radio’s keypad to put it into ‘crossband mode’.
   
8.  My CBR, a Kenwood TM-V71, has several menu settings for crossband use. These extra settings include Repeater Mode (one-way or two-way crossband), programming a Repeater ID that can be broadcast in CW (or Voice with an optional card) on both frequencies once every 10 minutes, and a setting to turn OFF the Automatic Power-Off feature. (Most APO’s turn the radio off if ‘idle’ for a predetermined period of time. Idle activity is determined by a lack of keypresses on the radio’s buttons. During crossband use, there is typically no button activity on the radio so the CBR could shut itself off when it times out despite being in use as a repeater!
9.  Operating in Crossband Mode – It takes a fraction of a second for the CBR to detect an incoming signal on one side and repeat it on the other side. If you’re crossbanding to a distant repeater, then it takes another fraction of a second for that second repeater to function as well. So when transmitting in crossband mode, hold the x,ot button for about one-half second before talking so that everything syncs up and the first syllable or two of your message doesn’t get clipped. 
10. Time-Out Timer – Unlike regular repeater stations, most CBR’s are mobiles (or even HT’s) and are not designed for heavy duty cycles (lengthy transmissions). To protect the transmitters, many CBR’s have Time-Out Timers to prevent the radios from overheating. The Kenwood TM-V71 will stop transmitting if the received signal on either side doesn’t un-key during any 3-minute period. [You may have to remind other users to let the repeater ‘drop’ and not quick-key responses so that the crossband rig won’t time-out.] 
    
11. Antenna – The crossband rig is typically a dual band mobile radio and as such usually has a diplexer built into it so that both bands operate through a single co-axial cable to a dual-band antenna. Nothing special is required for crossband use as long as the antenna can handle both bands at the full rated power of the radio.
    
12.  Transmit Power Levels – If you’re operating your HT in close range to your CBR, you can probably use a very low power level to transmit on the simplex frequency. Likewise, if you’re two-way crossbanding, you can use a low power setting on the simplex side of the CBR. The distance & conditions between the CBR and the distant station will determine the xmit power level for that side of the CBR. Using the lowest power level required to reach the other station is not only good amateur radio practice, but it also cuts down on the heat and workload of the CBR.
13.  Do Your Research – Read your CBR’s manual to become familiar with all the settings and options that affect crossband operations. Query the internet to read articles and see videos of how others have already accomplished what you might be trying to do. 
14.  Practice, practice, practice. Set up your HT and CBR and try them out. Pre-program your favorite frequencies in your radios for future use. Write down the pertinent information on a ‘cheater’ checklist that you can keep with your crossband rig so that when the time comes you can quickly go through the steps to set up the rig and be crossbanding when you need it.