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Tx Commissioning Is Far More Efficient Today

Welton says test and setup have benefited from manufacturing efficiencies

The Radio World ebook “Trends in Transmitters 2022” provides tips and best practices for shopping for a transmitter. This article is excerpted. Jeff Welton is Central Region sales manager for Nautel. He was the 2020 recipient of the NAB Radio Engineering Achievement Award.

Radio World: For someone who hasn’t purchased a transmitter in four or five years (or more), what should they know?

Jeff Welton

Jeff Welton: We created an ebook of our own for general and engineering managers that addresses what we consider to be the top nine issues involved and includes questions that should be addressed during the preparation process. It can be downloaded at our website.

A lot of the design and manufacture is based on reducing costs by eliminating manual intervention as much as possible. If we can have a test technician connect a transmitter to a computer, perform the initial power-up tests and measurements and then let the computer take over for the proofs and functional testing, the results will be more consistent and repeatable than if they were done by hand. 

Consider parallax when reading analog meters, for example — two different sets of eyes could get two different readings from the exact same meter.

This frees the technician up to handle other tasks and provides a higher-quality result. 

A consequence, though, is that part of the setup procedure will be to tell the transmitter what power level and frequency are required. Really, that’s a good portion of the entire procedure — these days, while not true for all manufacturers, most Nautel gear is shipped fully assembled, so the user simply needs to connect AC, connect the RF feedline, connect any remote control and audio wiring, then apply power. The transmitter will ask what frequency, what power level and what audio source. 

At that point, although additional configuration can be done, it could be put on air and be ready to roll within a few hours of taking it out of the crate. This is a big change from the days when it took three days with a factory tech on site to run through assembly and commissioning.

RW: Virtualization of the broadcast air chain has been in the news. What are the implications?

Welton: We’ve done some work with Telos Alliance on this, and it is still an evolution. However, one of the big factors I see as a future likelihood is that a lot of features that have traditionally been outboard could be virtualized and packaged directly into the transmitter. 

We’re already seeing this to some extent with RDS generators and the like being made part of the transmitter control system. Going forward, it wouldn’t be surprising to see situations where you could purchase a software license for your favourite processor, automation system or even control surface, virtualize it and install it directly into the transmitter controller, accessing it over IP and reducing the additional pieces of hardware that could be potential failure points. 

As a result, some attention will need to be paid to whether or not your transmitter has the capability to either handle this sort of thing from the onset, or has the hooks or capability to be upgraded to accommodate it. Definitely having the processing power to handle some level of virtualization under the hood can add a significant amount of flexibility in how you configure your operation.

RW: Hybrid radio platforms are becoming part of the landscape. What do transmitter buyers need to know?

Welton: The biggest thing will be RDS. Having it properly configured is going to be critical in a hybrid scenario, and reports are that stations with their RDS configured properly are by far in the minority. 

We covered this in one of my TTT (Transmission Talk Tuesday) sessions. We had David Layer, VP of advanced engineering for NAB, as well as Lawrence Galkoff, general manager of Radioplayer Worldwide, and there was a lot of information exchanged on how proper RDS configuration will impact how your station appears on a hybrid radio receiver — or if it appears at all. 

RW: Have supply chain issues affected you as a manufacturer? 

Welton: Absolutely they have. Longer lead times on components, components being rationed by their OEMs or the host countries, logistics challenges with moving parts or assemblies from point A to point B, they all play a part in how we do our jobs.

We’ve been fortunate to have leadership that has been quite proactive in getting ahead of these issues. So, while a transmitter that might have gone out the door six to eight weeks after receipt of order a year or two ago can now [as of October 2022] take 16 weeks or more in some cases, we’re still getting the job done. We’ve invested a lot of time, money and resources into finding alternate sources, building stock where possible and working with our suppliers and our freight forwarders to keep lines of communication open, especially if it looks like there’s about to be any sort of disruption. 

[Check Out More of Radio World’s Tech Tips]

RW: MDCL has been allowed in the United States for some time. What should engineers know about it that isn’t already widely known?

Welton: One of the big things is that the more aggressively you process the signal, the more impact the MDCL algorithms will have on the power bill, specifically the Amplitude Modulation Companding algorithm. 

Essentially, AMC reduces peak power on modulation peaks, so the higher/longer these peaks are, the more compression is employed. So, in a nutshell, the harder you drive it, the more it drops the power bill. 

Now, I’m not advocating half a dB of dynamic range and compressing all intelligibility out of the signal, but certainly it is something that might indicate a need for a conversation with your processor guru. 

Beyond that, the technology has more than enough hours behind it now to have verified repeatedly that it makes a very significant difference in the power bill with little to no negative impact on the received signal. Certainly if you’re running an AM station, especially at 5 kW or bigger, it’s something that should be considered quite carefully.

RW: What misconceptions do many people have about transmitters?

Welton: The biggest one is probably “we can’t afford it.” While that may be the case in some situations, in many it’s more a case of not being able to afford not to. 

Rather than focusing on the upfront price tag, which certainly can be frightening at times, it’s a really good idea to look at the whole picture. As an example, a grounded grid tube-type FM transmitter has a nominal overall (AC to RF) efficiency of 50%, compared to upwards of 70% for a current solid-state transmitter. That means a minimum 30% decrease in the power bill, month to month. While it usually won’t cover loan payments, that power savings will decrease the impact of a new transmitter purchase significantly and, once the loan is paid off that’s money going into the bank every month. 

Factor in higher tube costs and some challenges with decreasing life span in replacements, as well as the engineering costs involved with replacement and ongoing management, then it becomes even more significant. 

Sometimes, certainly, you can’t afford it. But again, sometimes you can’t afford not to. We have a handy cost of operation calculator available on the Nautel website.