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Let’s Talk New Transmitters

In many ways, the purchase of a new transmitter for your radio station is like the purchase of a house

In many ways, the purchase of a new transmitter for your radio station is like the purchase of a house. It�s expensive, obviously; it happens infrequently; it requires extensive due diligence; and finally, you need to be prepared to live with your decision for a long time.

In this edition, we�re going to examine some ideas and techniques you can use to ensure you�re making the best decisions regarding upcoming transmitter purchases.


A worthwhile strategy to consider is having two auxiliary transmitters, in addition to the main. There are transmitter models out there running fine after 25 to 30 years of service. Obviously, they have great track records � otherwise they would have been pushed out the door. The venerable Continental 816-series comes to mind; going back 40 years, the RCA BTF series is another.

This begs the question: Why should I get a new transmitter when the one I have works fine? And secondly, will new rigs work as well, over the long run, as my current one has so far? Those questions are easy to answer, unless you are dead set against taking advantage of new technology.

Reasons for buying new equipment include:

� Spare parts for old transmitters become harder and harder to source as time goes on, especially if the manufacturer no longer exists

� Older transmitters typically aren�t very good with respect to AC input to RF output efficiency � thus they cost more to run

� Tubes, while still available, aren�t cheap � thus adding to the cost of operation

� Older transmitters suffer from a complete lack of remote access � which is exceedingly important if you have multiple, far-flung sites to manage

If you have a transmitter that has been working reliably over a 30-year period, then the question about reliability of old versus new is answered easily: Your new one will not likely exceed the track record of the older one.

Ask yourself this, though: Will my 30-year-old transmitter be more reliable and easier to take care of than a new transmitter will be over the next 5�10 years? I would say, in the vast majority of cases, that answer is �no.�


There are many practical reasons for buying a new transmitter, including:

Relegating the current main transmitter to backup status

The need for more power output

Simply adding a new transmitter to take advantage of more modern features or HD

Adding a transmitter for a backup N+1 site

Let�s examine each of those in turn.


Each and every transmitter will experience a certain amount of downtime. I presume that your station management would like to remain on the air all of the time; so for that reason alone, a second transmitter is a necessity. If you currently have only one, then a reasonable plan is to relegate the �old� transmitter to backup status, and to put a new one in its place.

However, that project might not be quite as easy as it sounds, depending upon the circumstances, of course, because a certain amount of resources need to be available in order to accomplish this task.

You�ll need space for the second transmitter; you�ll need the electrical capacity; and you�ll need a means by which you can switch to the other transmitter by remote control.

The addition of a second transmitter also represents a fairly large commitment to extra expenses, so if management balks for one of the following reasons, let me suggest the following responses:

�We understand the need for a second transmitter, but we can�t afford to upgrade the building or the electrical feed.� One way around this is to buy a transmitter physically small enough to fit into a rack that already exists. Likely, you�ll have enough electrical capacity for this as well. Perhaps it will only have a 10 percent of the power capacity of your main�so this represents a big compromise on your part � but that�s a lot better than being off-air. Alternatively, a second transmitter can live in a different location (see more on this topic below).

�We can�t really afford a second transmitter � can�t you just work on the main during overnights?� Sure you can � but you don�t want to. No one does. It can be dangerous; it can ruin you for the next day; and frankly, it�s an imposition on any employee that an employer shouldn�t expect. It�s one thing to do it on an emergency basis; it should not become standard operating procedure.


Sometimes stations move or change antennas or change antenna locations on the same tower. Each of these reasons could compel you to purchase a transmitter that has more output power capacity.

Another reason for buying a transmitter with a higher output capacity, even without the reasons specified above, is the �loafing� factor. You might find yourself a bit more relaxed if you know your new transmitter was designed to put out, say, 20 percent more power than you require of it. That will mean less stress on power supplies and amplifiers on a long-term basis.


I mentioned the RCA BTF-series transmitters. For logic, all it had were two mechanically latching relays representing filaments ON/OFF, as well as PLATE ON/OFF.

The question could be put: Do you really need any more than that for any transmitter? The answer, really, is �no.�

If you were to look at old cars, though, for comparison purposes, you could make the same case: Older cars had the accelerator pedal, the brake pedal, the clutch and shifter. You rolled the windows down by hand and you used an actual key to start it, and to open the doors and trunk. We all know the newer car features that are commonplace nowadays. On one hand, we like them; on the other, they also break sometimes.

There�s a balance between complexity and trouble-free operation. It�s the same with modern transmitters.

Probably the most important addition to modern transmitters, from the perspective of the engineering department, is remote access. If you are responsible for sites that are spread out geographically; if you take care of the IT aspects at the station along with the studio gear; or if you are a one-man (or one-woman) department, then you need all the help you can get. The last thing you need to do is to take time to visit the transmitter site for information you could have easily gotten via IP access.

Another common feature in newer designs is built-in redundancy. With a vacuum-tube transmitter, you essentially have one amplifier element and one power supply. A failure in either knocks the transmitter off-the-air. Newer designs make use of multiple power supplies and multiple power amplifiers � and the failure of one (or more) doesn�t take the transmitter all the way off-the-air. Clearly, that�s an advantage for the station and the engineer who maintains it.

Ten years ago, during the initial rush to put FM-band HD Radio stations on-air, it was common to buy another transmitter for nothing but the IBOC power. A -10 dB coupler was a common way to inject the IBOC power in to the main antenna; alternatively, an auxiliary antenna was used for the HD transmitter by itself.

Today, common amplification is readily available, and transmitters that do it still maintain fairly good efficiency. If you are adding HD Radio, a new transmitter with common amplification represents the path of least resistance.


In two prior articles, I�ve espoused the benefits of alternate transmitter sites. (See and

All manner of things can happen at a transmitter site, many of which are out of your control.� Most of those can be remedied with an alternate transmitter site.� I�ll stay off my soapbox here, except to say that, in the event it isn�t practical to add a second transmitter at your current transmitter site, you should consider putting one somewhere else. If you happen to have multiple FM stations, an N+1 system can potentially become a backup for all of them.

An N+1 site needs more than just a transmitter, of course; it will need to be geographically situated so that it can serve as an aux for (hopefully) all of your main sites, from an allocations standpoint. You�ll need an antenna that can accommodate all the frequencies you have; and finally, you�ll need some sort of STL to make it all work.

This particular application really highlights the need for remote access of transmitters. The N+1 site will likely be used in emergencies, and the last thing you want is to actually have to go there to put it on-air. No system is really complete without full remote control capability, most (if not all) of which is going to be provided by IP communications.

There are many individual items at a radio station at times called �the most important piece of equipment we have!� I doubt there is any particular item that has more potential to give you grief. Therefore, planning for the purchase of transmitter is one of the most important things you will do.