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HD radio new transmitter vs keeping old and doing digital on dedicated antenna

S

stephend2

we're looking at doing hd radio..

Most cost effective solution to me seems to do digital only on a dedicated antenna placed close to the analog. Next option is to go with a new transmitter, do analog and digital on one antenna.

Station is on 105.5, analog TPO 2.3kw.

currently have 2 bay ERI antenna, would like to add another 2 bays for digital.

Is it worth trying to do digital independent of the analog and keep the existing transmitter which is a CCA FM5000G built around 2000.

I've heard its possible to adapt the old transmitter to run the digital signal along with analog but not much information on how that would really work out. I'm concerned about efficiency and tube life with even attempting that.

I'm looking to speak with some people who have "been there, done that" with HD.
 
stephend2 said:
we're looking at doing hd radio..
Click to expand...

Don't. Right now, receiver penetration will not make the money spent on putting an HD signal on the air worth it. And no matter how much you think it's going to cost, you can count on it being twice that when it's all over.

Going HD just to say you are HD isn't really worth it for an FM station unless you have a solid business plan to take advantage of ancillary audio streams.
 
At that power level doing a combined antenna would be easy. That would mean a new transmitter though, but either way you will need one to do HD.

I am in favor of using the combined antenna for many reasons, mainly for the two carriers to match in their patterns. Having two antennas at different heights does work since they are different but I have experienced how that can not be good in hilly terrain sometimes. All in your preference and how you want to run your plant.
 
I'd second Bengals Fan but if you have a management issue where they are determined to "do this here digital thing" because "they need to reach the kids listening to mpeas in their e-pods"; then I would go with the separate antenna system.

Understand that the IBOC system requires a linear amplifier, unlike the analog FM signal. Hence the ratings on the new transmitters that show a much lower power for digital operation compared with analog.

You stated the station is 2.3 kw tpo into unity gain antenna--I would guess then that your ERP is in the 2 kw range, not knowing feedline length. Hence your IBOC power, even at 10%, is limited to 200 watts or less With a combiner system you will have a ton of money sunk into nice, useless (when you abandon IBOC) copper plumbing. This would allow you to continue to use the CCA, though, as you are combining the two signals at high level. Trying to make the CCA linear enough to do low-level combining is probably an exercise in futility. As you have already figured out, the separate antenna system is cheaper.

The IBOC exciter is now the main expense, find one that will also fall back to analog without too much hassle. Then you need a power amplifier. Look at the Nautel "V" series, they have an amp that puts out 1.4 kw analog, or 400 watts HD. With this combination you can drive a single bay antenna, such as the SWR FM/1, which is rated at 500 watts (and costs a little more than a buck a watt).

Why go this route? Well, as soon as the "suits" figure out that the public and advertisers are greeting IBOC with a collective yawn, you become a hero by re-purposing their investment in equipment when they abandon IBOC.

1. Let's assume the IBOC exciter also will give you about 40~50 watts analog, so now you have a perfectly good new analog exciter (with some expensive added useless circuitry).
2. If you are persuasive, you can convince them to buy the combiner and second kilowatt amplifier to add to make your Nautel V-1 a V-2. Now you have a completely new 2.5 kw solid state transmitter. Hook it up to your existing ERI antenna.
3. Take the exciter from the CCA and hook it into the SWR antenna. Good emergency antenna if you don't have back-up power--you could run things off a little portable genny.
4. Sell the carcass of the CCA 5. You don't need it--if either amp or the combiner burns up, you just feed the other amp direct to the antenna while you get things repaired. Instant half-power backup.

(I have the Nautel V2 if you would like more info on that unit. Wouldn't touch HD with a 10 foot pole, however.)
 
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