Nobody likes listening to a BAD presentation.
If you aren't prepared, your audience will know (think back in time... once, you were in fifth grade, and you were supposed to recite a poem in front of the class. You didn't know it, did you? (BTW: "October's Bright Blue Weather" for Miss Klir's English class was the poem we all had to learn, which I've since forgotten) All the class laughed, and you had to do it again a week later.
Well, maybe you didn't have to do it over, but I bet you remember the kid who did, right? And snickering mercilessly?
Where am I going with this? Why is this on my ham pages?
Excellent questions, all. The local ham club will no doubt want to hear tales of your latest exploits at one of their meetings (don't all ham clubs invite members to speak on various radio topics?). The problem is, while anybody can do a hit and run QSO (tnx #793, ur 59 hr, qrz?), it takes a bit more of a communicator to actually speak for as little as 5 minutes.
Example topics: Cross Band Repeaters built into dual-band mobile radios.
Bad presentation: I got an Alinco DR-605TQ in my truck outside, and when I transmit on 443.25 you can hear it on 147.555. It's real cool. Y'all wanna try it out?
(Believe it or not, that's actually not so bad... we learned that somehow, signals on 443.25 got onto 147.555. There was 1 piece of information there! An intelligent listener might figure out what you were talking about.)
For slightly less bad presentation, add on: You can also do that with an Icom 2600. Any questions?
Even hams do get bored hearing manufacturer's and model numbers and nothing else. We neglected to answer many key questions, and we didn't put it in the format which I was told to put presentations in by my Sixth Grade Social Studies teacher (Mr. Nesheim -- Hi, Neighbor! (he always walked in the room whistling the theme from Mr. Rogers Neighborhood).
What are we talking about? Crossband repeaters. What do they do? How do they work? When can you use them? When CAN'T you use them? What special restrictions does this place on the user? (Finally) What equipment can be used to crossband repeat? Any funny things we should expect that we can't do?
The magic formula, drilled into my head by Mr. Neshiem (yes, he actually said this):
Better presentation: (after introduction) Thanks, (Sam / Randy / George / Linda / Insert Emcee's name here). I'm here to talk about Crossband Repeaters, FCC Rules relating to Crossband Repeaters, and some basics on Crossband Repeater use.
(Tell 'em what you're gonna tell 'em!)
First of all, a repeater is a radio that listens on one frequency, and transmits what it hears on another. You're probably all familiar with our local 2m 146.94 repeater - that's what it does. It listens on 146.34, and transmits what it hears on 146.94. This is a very common arrangement. A crossband repeater is a special subset of this: it typically listens on 70cm, and re-transmits on 2m. For example, I've got mine set up for 446.45, and 146.94-. That means whatever it hears on 146.94, it'll repeat on 446.45, and whatever it hears on 446.45 it'll repeat on 146.34. The big advantage of this, is that I can use my 70cm handheld on low power, and still hit the repeater full quieting, as long as I'm within a few blocks of my truck.
Any questions so far?
(Tell 'em - and how!)
Now once we've set up our radio to be a repeater, it's just that: a REPEATER. The FCC rules for repeaters are pretty simple: You have to ID every ten minutes, and since the repeater is likely under automatic control, you need to time-out after three minutes. The EASIEST way around this is to park a licensed control operator at that radio, and every ten minutes, have them pick up the mike and ID both the UHF and the VHF channels. Then, since they're right there, it's also not under full automatic control because you have an operator at the control point, there's no timeout required. Unfortunately, this is impractical most of the time. Most radios don't have an ID'er in them, so one needs to be added for legal operation. This is harder than it sounds, because you probably don't want the crossbander to ID the 2m side and annoy the regular repeater users. Besides, you did say your ID last time you transmitted, so THAT side did ID. So, your ID circuit needs to tell when the UHF transmitter was keyed, and then within ten minutes, key the UHF side and ID.
Everybody got the basic rules there?
There are some more specific rules - certain blocks of frequencies that you can't use per FCC rules, and certain frequencies you're encouraged to use by the local frequency coordinators for your handheld-crossband link. There is also a little bit of question on is this considered a repeater, or an auxiliary station - from what I understand, it's subject to both rules. This means that the "control" side of the link can't be below 220 Mhz, so you can't use your 2m handheld to hit the 70 cm repeaters in the area - it's illegal. Before you turn your radio into repeater mode, you should probably have a review of the FCC Part 97 Rules just for good measure.
I'm sure you're wondering which radios can be used. Many Kenwood, Icom, and a few Alinco radios have this feature. Specifically the ones I remember are the TS-2000, the IC-2600, and the DR-605. There are more, so if you're looking for a shiny new radio at the candy store, you should ask if your new prize will crossband repeat. I know that this is usually one of the categories in the radio comparison chart for VHF/UHF mobiles, as it's becoming a popular feature. While many radios will crossband repeat, not all will let you change frequencies over the link, or otherwise allow for remote control. That's probably something you should look at, and make sure you know the limitations of whatever radio you're getting.
If you've already got two separate single-band radios, it's probably possible to link them together using an outboard controller. Some repeater controller companies do make controllers specifically for this purpose! I know specifically that the MCC RCC-100 will do this, but ask any repeater controller company if their controller has a crossband mode. I expect that most controllers that support a remote base could be used as crossband controllers. Just remember that the control side should be above 220 Mhz.
Any questions so far?
The problems: you usually can't do an autopatch through the crossband. When autopatch is on, the carrier never drops on the 2m side, so the radio never starts listening on the 70cm side.... so you don't get to talk, and you can't hang up the phone! Also, it's sometimes hard to check into net through a crossband repeater, because Don doesn't let the carrier drop for long enough to get through. I don't have this problem when Daniel is net control, however. (Everyone may chuckle at this point.)
(See, tell 'em!)
More questions before I turn it back to Linda?
OK, Final review: Crossband repeaters can extend the range of your HT, but you can't autopatch, and there's certain frequencies that you're not allowed to use. Anybody who wants to play with it, I'm going to hang out after tonight's meeting for about 30 minutes, so grab your HT's and I'll see you in the parking lot. Thanks!
(Thunderous applause, since this was a not-bad presentation!)
Lots of information, somewhat organized, use note cards, pause often for questions.... throw in a joke now and then, and don't be equipment oriented (unless you're talking about 1 specific radio, and you're reviewing it for the club, and you're giving LOTS of information on it).