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“We have seen savings from 21% to over 40% at our 50 kW stations… and I would challenge anyone to detect that we are employing MDCL.”

-Cris Alexander, Director of Engineering, CBC

Why Nautel’s NX25 and NX50 are Ideal for MDCL:

  • MDCL comes pre-installed
  • FREE: no additional charge
  • Easy & fast to switch on
  • Standard software feature


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NX Series

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“Thanks to Nautel, not just for providing this excellent software update, but for doing so at no cost to the end user. I was a big fan of Nautel before; now I’m an even bigger one!”

-Stephen Poole, CE, CBC-Alabama

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Crawford Saves 21% to over 40% With MDCL


Crawford Broadcasting is one of a growing group of broadcasters building up experience with Modulation Dependent Carrier Level (MDCL) power-saving techniques since the FCC started allowing U.S. AM stations to start use this technology in September, 2011.

Crawford is currently utilizing MDCL technology on six Nautel transmitters across five AM stations.

Coverage & Sound

Crawford’s Director of Engineering, Cris Alexander reports, “I have had the opportunity to evaluate the effects of the MDCL operation on the signal firsthand and… well… I haven’t detected any! The signal is strong and robust, maybe even louder than before, and the digital performance is outstanding (on KLTT we get a digital lock in about two seconds on most receivers)”.

Cris-Alexander-Crawford-Broadcasting “We employ the AMC MDCL algorithm due to its minimal audible impact and because it so well masks the signal-to-noise reduction during quiet passages. I have observed no impact on the coverage or signal-to-noise ratio in the fringe areas of our talk format stations when using AMC with 3 dB of carrier reduction.”

“In terms of station sound, there is very little impact that I can discern. If anything, our stations employing the AMC algorithm sound louder with MDCL enabled. This is probably a function of the receiver AGC increasing the RF gain during modulation.”

“I would challenge anyone to detect that we are employing MDCL on any of our stations. Based on my observations over the months we have had MDCL in operation, I don’t believe they could.”

Cost Savings

Crawford has experienced savings from 21% to over 40% at their 50 kW stations, depending on the situation.

Cris reports, “The lower savings are at a transmitter plant collocated with the studios and offices, so the transmitter is a smaller part of the overall electrical load at the site. The higher savings are at stand-alone transmitter plants where the transmitters are the lion’s share of the electrical load. We typically see about 5% in savings at our 5 kW stations, mostly because the transmitters are a relatively small part of the overall electrical load (in some cases the tower light power consumption exceeds that of the transmitter).”

MDCL Pre-Installed & FREE on NX Series

Nautel-Crawford-MDCL-Story-Stephen-Poole Chief Engineer of CBC-Birmingham, Stephen Poole comments, “I knew that the shortwave guys had used this for many years… it’s a beautiful thing and Nautel is to be highly commended… not just for providing this excellent software update, but for doing so at no cost to the end user.”

“Nautel could have charged a pretty penny for this and it would still have been worth it. The fact that they’ve done it as their part to make the world a little ‘greener’ says a lot about that company. I was a big fan of Nautel before; now I’m an even bigger one!”


Commerce City, CO
MDCL Implementation Date: January 2012
Nautel Transmitters: NX50 and ND50

“Enabling the MDCL option on the new KLTT NX50 was a piece of cake. Everything worked as advertised!” says Cris. “As with KCBC, WXJC and WYDE, this station is employing the AMC algorithm, which reduced the carrier with modulation (the carrier returns to full power during low or zero modulation).”

“As with KCBC, I could not detect any observable effects, even in the fringe area on the west side of the continental divide. What I could detect was a 21% decrease in energy usage at the site for the month of January compared to January of 2011. That is right in line with the KCBC savings.”

Nautel-Crawford-MDCL-Story-KLTT-NX50-Amanda-Alexander After activating MDCL on the NX50, it occurred to Cris that they would never again be able to run the ND50 auxiliary at full power without incurring a big power bill from the peak demand (as well as the actual kWH usage).

“Nautel came to the rescue with a firmware upgrade for the AM-IBOC HD exciter, and we performed the upgrade to implement MDCL on the 16-year-old ND50.”

“Now we can run it anytime without worrying about taking that power hit. We have tested this during maintenance and it was great to see the carrier power dipping to 26 kW or so during modulation.”

Crawford Engineer, Amanda Alexander (pictured left) shares her story with Radio World, June 20, 2012 >>


Manteca, CA
MDCL Implementation Date: Late October, 2011
Nautel Transmitter: NX50

Since activating MDCL at KCBC, Cris has seen a consistent reduction in power usage of 21% compared to the same period last year. “We have observed this in the November, December and January billing periods. We have observed no degradation in perceived signal to noise ratio even in the fringe area.”

Chief Engineer of KCBC, Steve Minshall reports, “We have been using the AMC mode with outstanding results. The transmitter is a Nautel NX50 and while already very efficient the use of MDCL has reduced power consumption even further.”

“The reduction in heat output from the transmitter is significant, to the point where the air-conditioner seldom runs, another power savings. At KCBC we run 100% closed circuit air-conditioning for the transmitter building. This keeps the air cool and clean and keeps the dirt and bugs outside. It is amazing to see a 50 kW transmitter operating in a closed room with so little heat output. Lower heat means less stress on parts so that is an added bonus and probably long term cost savings.”

“50 kW transmitter sites are often supplied power through a peak-demand meter and such is the case with KCBC. The AMC mode reduces carrier power as modulation increases thereby reducing peak demand. So we save electrical costs in two ways. Not only do we save in kilowatt hours consumed but the peak demand multiplier is lowered for another reduction in power cost.”

“On-air performance could not be better. We actually seem to be slightly louder with the AMC MDCL. Coverage seems to be unaffected. So far we are saving about 21% in electrical costs over last year. There does not seem to be any down side to using MDCL and it may cause one to wonder why this was not done before. With the NX50 it was a very simple change to make, the cost is zero and the savings begin immediately.”



Birmingham, AL
MDCL Implementation Date: December 2011
Nautel Transmitter: XL60

Nautel-Crawford-MDCL-Story-WXJC-XL60 Crawford was informed by Nautel’s Brian Walker that a firmware upgrade was available for the AM-IBOC HD exciter that would permit MDCL operation from any Nautel transmitter equipped with Mag and Phase drive inputs.

Their Nautel XL60 at WXJC, a 50 kW AM station, fit that description very well, so Chief Engineer, Stephen Poole performed the required firmware update on the AM-IBOC HD exciter to enable the MDCL option using the AMC algorithm with 3 dB of carrier compression.

“On the first software iteration, our carrier with average modulation was running about 26 kW on the XL-60’s power meter. With the second attempt, it’s a little higher – 30 to 33 kW – but there’s still a substantial reduction. I am very anxious to see what this does for our power bill.”

WXJC has not yet evaluated their power savings from January to February, 2012 but expect to see 20% or more.



Birmingham, AL
MDCL Implementation Date: January 2012
Nautel Transmitter: ND5

Stephen wanted to try MDCL on 5 kW WYDE as well, not so much for the energy savings but as a way to reduce wear and tear on the power modules. Historically they replace some of the transistors (especially the modulator MOSFETS) about every 1-2 years. Stephen’s hoping that allowing the transmitter to “cruise” at a lower nominal level will help. As with WXJC, all it took was a firmware upgrade and enabling the MDCL option.

Prior to WYDE, all of Crawford’s MDCL conversions were on 50 kW stations. They opted to try it on a 5 kW to see if the power savings would scale and are awaiting billing from the power company to evaluate this.


Compiled from customer testimonials and The Local Oscillator – the Newsletter of Crawford Broadcasting Company Corporate Engineering

Cris Alexander, Director of Engineering
Stephen Poole, Chief Engineer, CBC-Birmingham
Steve Minshall, Chief Engineer, KCBC
Crawford Broadcasting Company

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