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“My GV10 running at ½ power with -14dBc injection is achieving 74.8% efficiency. When run into a dummy load at full 9 kW output with -14dBc, that number jumped up to 89%! Not much wasted juice there!”

-Alex Hartman, Chief Engineer
 
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Learn more about the GV Series for 3.5 – 88 kW Analog/Digital FM

 

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“Nautel has made a ‘UPS interface’… it allows ‘inlet’ ports from a standard off-the-shelf UPS. It’s the little things like this that set Nautel apart from their competitors.”

-Alex Hartman, Chief Engineer

User Report: First GV10 Goes on Air

 

Nautel has been leading the technology charge in radio transmission systems now for over 40 years and has managed to go from a little Canadian transmitter company who mostly made AM transmitters to arguably the number one transmitter company in the western hemisphere and making inroads all over the world with AM, FM, TV, and even their original staple, the navigation beacon.

The GV Series is no different to that mission and is a culmination of the previous generation NV and the NVlt with some new goodies thrown into the mix. It is quite “bleeding edge” technology for the radio transmission industry.

Nautel-GV10-Transmitter-KVSC-StoryThe GV Series incorporates LDMOS fet technology allowing for greater efficiency in the design. This paired with Nautel’s now standard “PowerBoost” software, where once a 20 kW transmitter would be required, the GV will probably only require 15 kW (with HD IBOC running at -14) or even less. AC-RF efficiency of the NV Series was around 45%(+/-5%) running at -14dBc, the GV will trump that by 10% or more, that’s quite the savings when it comes to power and cooling bills. For comparison, the NV10 is capable of 7 kW analog TPO at -14dBc HD injection, where the GV10 is 9 kW analog TPO with a -14dBc injection. 2 kW of analog increase is quite a bit in the same footprint, but I’ll get to the HD part later on.

In the analog realm, the GV Series is capable of the same old things we’ve been seeing since the mid-60’s; composite audio input from your favorite audio processing company, metering and control, harmonic suppression well below -80dB, etc. Okay, so it’s an FM transmitter. Here’s where Nautel took it to the next level. With the introduction of the NX and NV Series transmitters at NAB 2008, they started interfacing their transmitters with what they call “AUI” or Advanced User Interface. I won’t bore you with what you likely already know about AUI, but focus on the really neat stuff it allows you to do and see, within the line of transmitters that utilize it (pretty much the entire Nautel line with the exception of the XR/XL/J Series).

Nautel-GV10-AUI-Advanced-User-Interface-KVSC-StoryThe AUI replaces all the analog metering that you would be used to seeing on any other rig, but it gets a little (okay, a lot!) more detailed than that. It will show you the FAN RPM speed on all the modules, the individual voltage levels on almost every discrete component in the unit, temperatures, various levels of efficiency, and it will even email you if something goes wrong. How neat is that!?

The GV Series is no different from the NV in that respect, but they have added some other goodies like a basic remote control with relays and metering. No need for an outboard remote control, the GV Series incorporates that for you. With the GV Series, unlike the NV, you can also get the Orban Inside card which effectively adds an Orban 5500 on a card to the transmitter, also controllable via the AUI.

Now, I know a lot of people will say “that’s a lot of eggs in one basket, Alex!”, and you’d be right! Here’s the thought process behind it. If there’s a catastrophic event, say a power outage, is the outboard gear of any use to you at that point? Probably not. Something like the antenna getting struck is the only time where the outboard gear might save your bacon with a backup rig. But sometimes even having a backup full power rig at the same site is a luxury these days. So, I would say that yes, it’s a lot of eggs, but for the 99%, it will probably suit you just fine.

The other very intuitive thing that the NV and GV Series both incorporate is the ability of “PUSHRADIO”. ENCO designed for Nautel a basic automation system built into the transmitter; it’s now a function of the firmware from Nautel, so anything capable of running the AUI can utilize this feature. This is particularly useful for sites with local insertion, or as a backup in case of STL failure.

The GV Series AUI also incorporates several other things, like a built-in spectrum analyzer to show you if you are running within compliance, and an Oscilloscope function to look at various points within the air chain if you have issues with audio quality. Now we’re replacing test equipment with the transmitter. A decent spectrum analyzer will set you back a few thousand bucks at minimum for the new Rigol units, and a good Tektronix scope costs about the same.

So, the AUI is pretty cool for us computer geeks. It gives us a level of control and features not seen before on any other transmitter. A few others have started incorporating similar features, but not to this level quite yet.

Now that we’ve looked into the software, lets dive into the hardware a bit more.

Nautel-GV10-Transmitter-Open-Front-KVSC-StoryThe GV10 has done away with any IPA stage, so it is now a direct-to-PA modulated system. The exciter generates enough horsepower (both analog and digital) to feed the four PA stages directly, removing yet another point of failure. The GV Series can be outfitted with two exciters for a failover situation for those insecure types out there. The exciter is capable of taking not just composite baseband audio – analog audio, AES digital audio, and IP audio from say a Shoutcast/Icecast stream – but is also AES67 capable. This is the new MPX over AES spec pioneered by Nautel and Omnia, keeping the entire air chain digital through and through. You have now several options of audio delivery for pretty much any design.

There is a familiar VS Series panel on a new controller module utilizing the CrystalFontz LCD and six-button panel we see on everything today from satellite downlinks and codecs to transmitters. So, if something goes wrong with the SBC controlling the AUI on the front door (it is just a little ITX-style PC board after all), this panel gives you piece of mind as it allows access to most controls within the GV Series. The controller also sports a pair of USB ports for a thumb drive to be inserted for various functions, including backup audio, firmware upgrades, Orban preset saves, etc. They are simple USB 2.0 ports that provide 500mA, so don’t expect them to charge your iPad while onsite. The controller also has RF On/Off buttons and a Local/Remote button as well.

The controller has another trick up its sleeve; a “mimic panel” that contains all the local wiring and an Ethernet pass-through jack for remote control. It has basic buttons such as raise/lower power, change preset, RF on/off, and the much-favored local/remote button. You can get this board optionally or go right to the DB25 pins on the back. I find the board more favorable. Having the control in a convenient location for diagnostic purposes is easier to use a “greenie” (which is supplied by the way!) to connect house wiring than soldering a DB25 and interfacing it with a remote control or punch block.

The GV power supplies got a bit of an upgrade from the NV series. These are GE made, 50v, 2750 W per unit power supplies. My GV10D came with 10, all identical. The outer four on either side are for the PA decks and the inner two are for low voltage items, such as the controller, exciter, etc. These supplies are hot-swappable and the transmitter folds back when one is pulled or failed. Interestingly, Nautel has made a “UPS interface” for this transmitter. It’s not for the PA power supplies however, it’s just for the low voltage to handle brownouts and bumps in the power, thus negating the reboot time of the exciter and controller. It allows “inlet” ports from a standard off-the-shelf UPS (like those you would find on an RV for a generator). It’s the little things like this that set Nautel apart from their competitors.

Nautel-GV10-Transmitter-Wiring-Ducts-KVSC-StoryTaking the back panel off is done with about a dozen ¼-turn plastic clasps. There’s really not a whole lot going on back here. There is an interface board for all the PA modules, a traffic director that controls the bias of the PA for dynamic HD IBOC injection, and the wiring harnesses. The new thing however, is the addition of “wiring ducts”. What a simple, yet very effective idea. This was suggested by several Nautel users and lo and behold, Nautel was listening. There are two ducts on either side of the transmitter in the back. One is for your AC power wiring, the other is for all of your control, audio, and interface wiring. The AC wiring duct goes all the way down past the main rear cavity into the power supply cabinet and pops out right next to the AC mains wiring lugs. This keeps everything safe and protected; nobody can accidentally climb around the AC line voltages with random screwdrivers. The other duct goes from the top inlet down to the bottom of the main PA section where the controller and exciter live. In my particular installation, I had to route about eight cables into it for various items (mod monitor, composite, AES audio, 10 Mhz GPS sync, control/status wiring, two ethernet cables). It gets pretty tight, you will want to terminate the cables once they’ve been installed as getting XLR or BNC connectors to bend is tricky business!

The GV Series also comes pre-wired for any options you may purchase in the future, such as the extra exciter or UPS option. All you have to do is buy the items from Nautel and drop them in, all the cables are there waiting for you.

One thing you will notice about the GV Series and even the NV/NVlt series is how amazingly light they are. Fully crated my GV10D was just shy of 700 pounds, uncrated and on the ground it’s just a tad over 415 pounds. A couple of guys can walk this thing around pretty easily compared to the big iron-wielding monsters from just a few years ago. With that in mind, be careful not to torque the box too much walking it around into position.

The ancillary kit that comes with the transmitter also contains several ferrite rings for audio lines, transmission lines and other items you may wish to protect.

Nautel-GV10-Transmitter-Open-Back-KVSC-StoryTurning to the HD side of things, the GV Series is a little bit of old trick, new trick when it comes to IBOC. The NV Series power curve was different depending on where in the band you were. It would be a little more efficient on the upper parts and less on the lower. The GV however, is flat across the board. No matter the dial position, the LDMOS fet Nautel has chosen is “flat” over the FM band as far as power curves are concerned. So, 88.1 or 107.9, you will see the same efficiency. Speaking of efficiency, I previously mentioned that the AC-RF numbers are impressive, but the DC-RF numbers are equally as impressive. All the power is going where it needs to go once it comes out of the DC side of the supplies. My GV10 running at ½ power with -14dBc injection is achieving 74.8% efficiency. When run into a dummy load at full 9 kW output with -14dBc, that number jumped up to 89%! Not much wasted juice there! A -10dBc injection at 6.5 kW power output (the max analog power for the GV10 at -10) brought that number down around 79%. This is in part the LDMOS fets employed along with PowerBoost doing its magic in software. The GV Series is also capable of asynchronous sidebands, with a push of a few buttons on the AUI in the Presets menu, you can have a -10 lower and -14 upper.

Another new trick the GV Series has is the “HD Spectrum / Efficiency Optimizer”. This software function is quite innovative. It is a set of “rules” the transmitter follows to maintain an absolute maximum IBOC output based on YOUR specifications, not Nautel. If you want to maintain a -1dB clearance on the IBOC mask, just tell it to do that, and it will adjust the PA voltages appropriately. Again, no constant tweaking to make sure your plant is always running at its top capacity. They’ve taken the guess work out of it here as well.

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Another thing to keep in mind, unlike previous generations, the rated power on the GV Series is “worst case”, meaning MP3 HD mode is what the rated power is, so you don’t have to worry about calculating in the extra overhead for MP3 mode, Nautel has taken that guesswork out of it for you.

At the end of the day, it’s a transmitter, but it’s a transmitter with a boat load of features replacing several other items within your air chain and tool chest. The touch screen on the front gives you an at-a-glance overview of the performance of the box. Color-coded buttons show you warnings, alarms, and other status. Of course with the Nautel comes their standard four-year warranty. With an IP-enabled site and utilizing Nautel Phone Home, the factory will be informed of impending problems and failures most likely before you do. If there’s a software issue somewhere, Nautel has put their own “support” system into the GV Series of transmitters that pokes an outbound hole through the firewall and allows the support team into your transmitter for further diagnostics. No running around with third party “remote desktop” suites, they have their own set of keys.

As always, Nautel is always listening to their users’ advice and input as well. If the feature makes sense, they will probably implement it. The GV is born of a lot of these suggestions as seen here. It’s a “software defined transmitter” as I have been calling it. A lot of functionality potential exists inside and I’m sure we’re not done seeing some of the stuff Nautel has planned for this very versatile platform.

Would I recommend a Nautel transmitter? Absolutely. I’ve gone from owning a single VS1 to having two VS300LP’s and now the GV10 in my fleet. With the customer service I’ve received, I wouldn’t hesitate to recommend them. They are not always the cheapest guy on the block, but the extras you get like Phone Home, the Orban Inside options, not to mention the customer service puts them on a pretty high shelf. Nautel continues that tradition here and hopefully into the distant future. And it’s always mentioned, they have NEVER discontinued a product in 40+ years. Find another company who will say that in public, I dare you.

Alex Hartman, Chief Engineer
KVSC, St. Cloud State University, MN


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