It’s an RF jungle out there…
And it’s increasingly becoming our job to navigate through it. Despite all the discussion, organization, and legislation, it looks like the FCC is moving forward to progressively sell off more UHF space in the 600 MHz band to big telecom. So we must adapt, and having powerful, flexible tools that can utilize the most of our wireless space is key to our survival.
The Sharkie, Betso’s new active variable gain LPDA antenna, is one of these tools. With its compact size, adjustable gain, and weather-resistant construction, the Sharkie is ready to hunt wireless signals, wherever your jungle happens to be.
Details, details.
With its epoxy-reinforced fiberglass body, and weighing just below 320g, the Sharkie is leaner and meaner than other active LPDA fins. For more durability, the amplifier is made of machined aluminum alloy, and fully sealed from the elements.
The Sharkie’s skeletal and streamlined design reduces wind resistance when outdoors, and it has both ¼’’ and ⅜’’ threading for expanded mounting possibilities.
Betso designed the Sharkie’s mount directly underneath the amplifier instead of its base, improving balance when mounted on masts. This could provide more range of movement for all BNC connector/boot sizes, which is a welcome feature when using thicker, longer runs of heavy duty antenna cable.
And boy does it look sharp too!
Crank it up! (or turn it down)
LPDA “sharkfin” antennae, whether passive or active, have been a staple for sound carts, backstages, and FOH desks alike. But the Sharkie’s ultra low-noise amplifier/attenuator can adjust gain from -9 to +18 dB, accommodating any cable lengths or incoming signal strengths. To date, this is the widest gain range of any active sharkfin, with other models offering on average -6 to +12 dB.
| Betso Sharkie |
Lectrosonics ALP650 |
PSC Power Paddle |
Shure UA874 |
Wisycom LBNA |
|
| Amp Range | -9 to +18 | +5, 8, 12 | +4, 6, 8, 12 | -6, 0, +6, 12 | 0 to +15 |
Furthermore, with its membrane button control, adjusting the Sharkie’s amp is simple, without the need to dig into dip switches, or disassemble the unit completely to swap jumpers. Increasing or decreasing gain is only a couple button presses away, in 1 dB increments.
Betso also added an ambient light sensor to the Sharkie’s two-digit LED display, which automatically adjusts brightness for the best readability and behavior in both dark and radiant environments. The LED display brightness can also be controlled manually, or turned off completely.
Silence is golden
At maximum gain, the Sharkie’s amplifier (integrated circuit) has a NF rating of 0.75 dB, keeping self-noise to an impressive minimum. Combine this with a standing wave ratio (VSWR) of less than 1.2:1, further decreasing the chance of gain loss or reflected transmissions, plus more than 34 dBm of intermod performance, and aggressive band filtering below 450 MHz and above 850 MHz.
Nerd-speak aside, what does this mean for sound professionals? Simply put, by raw spec alone, the Sharkie captures the most from your RF transmission, with very little distraction.
Let’s get to business
For our “real-ish world” testing, we’ll be using the Sharkie fins on a vertical mast or secured to surfaces with grip arms. The results will be an average of testing with several RF distributors, such as Lectrosonics’ Venue, and Sound Devices’ SL-6, used for a range of scripted narrative or reality/documentary productions.
We’ll also be testing the Sharkie against other popular LPDA fins with integrated amps, such as Lectrosonics’ ALP650, Shure’s UA874, and Wisycom’s LBNA, in different troublesome locations around Los Angeles. Here are some real-world scenarios we’ll test:
- RF Level: dBuV, mast, 100 ft distance, various locations
- RF Level: dBuV, 100 ft of RG8-X cable
- RF Level: dBuV, 100 ft of RG8-U cable
- Maximum Rural & Urban Distance
With all testing, we’ll utilize the popular Lectrosonics SMQV at 100 mW output, using the best coordinated frequency at each location. With the exception of long cable tests, the amplifiers will be set to 0 dB gain because my mast cables are less than 20 feet long.
There are probably better, more scientifically controlled ways to perform these tests. Many environmental and mechanical factors can affect wireless performance. The following results are simply my records while working on productions around the Greater LA area — let’s begin!
Test 1: Avg. RF dBuV @ 0 dB Gain
| Betso Sharkie |
Lectrosonics ALP650 |
Shure UA874 |
Wisycom LBNA |
|
| Downtown LA | 55~60 | 40~45 | 35~40 | 50~55 |
| Griffith Observatory | 40~45 | 35~40 | 30~35 | 45~50 |
| Elysian Park | 45~50 | 30~35 | 25~30 | 40~45 |
| Sony Studio Lot | 60~65 | 45~50 | 45~50 | 60~65 |
| Long Beach | 55~60 | 40~45 | 40~45 |
55~60 |
In this test, we compared performance between sharks in an average cart-based scenario while on production. The antenna were placed on a K-Tek antenna mast, raised about 10 feet high, generously above any bodies or other equipment.
The subject stood about 100 feet or 30 meters away, with his transmitter clipped onto the belt line in the small of his back, antenna placed vertically, and mic clipped onto his shirt.
Both the Betso and Wisycom antennae outperformed Lectrosonics and Shure, with some variations at each location. However, when the subject moved around, the Sharkie experienced less fluctuation in signal strength than the LBNA.
Test 2: Avg. RF dBuV @ Amplified dB, 100 ft RG8-X Cable
|
Betso |
Lectrosonics ALP650 (+8 dB) |
Shure UA874 (+12 dB) |
Wisycom |
|
| Downtown LA | 50~55 | 35~40 | 35~40 | 50~55 |
| Griffith Observatory | 45~50 | 30~35 | 30~35 | 45~50 |
| Elysian Park | 40~45 | 25~30 | 30~35 | 40~45 |
| Sony Studio Lot | 60~65 | 35~40 | 40~45 | 55~60 |
| Long Beach | 55~60 | 35~40 | 40~45 | 50~55 |
Next, we set the antenna mast on a stand and tried two heavy duty coaxial cable gauges: RG8-X (¼’’ diameter), flexible but more susceptible to loss, and RG8-U (½’’ diameter), very low loss but rigid and challenging to handle.
Because each fin has different amplification settings, we chose gain settings that were as close as possible to each other. So the ALP650 experienced the most loss because it didn’t have enough amplification to compensate for 100 ft of RG8-X cable.
Correction: During this review, we initially misunderstood the ALP650’s jumper values, and set it to a resulting gain of +8 dB, while the “0” jumper setting was representative of +12 dB. Therefore, the ALP650 is capable of driving this cable type & length.
Likewise, the Shure fins have only +6 or +12 settings, which may have provided too much gain for this length, adding extra noise to the signal. Already, we see the benefits of having gain control of 1 dB increments.
Signal attenuation also differs depending on wireless frequency. We use several transmitters between 486~570 MHz, which equates to about 10 dB loss with RG8-X, and 5 dB loss with RG8-U… which leads us to the next test:
Test 3: Avg. RF dBuV @ Amplified dB, 100 ft RG8-U Cable
|
Betso |
Lectrosonics ALP650 (+4 dB) |
Shure UA874 (+6 dB) |
Wisycom |
|
| Downtown LA | 55~60 | 40~45 | 35~40 | 50~55 |
| Griffith Observatory | 40~45 | 35~40 | 35~40 | 45~50 |
| Elysian Park | 45~50 | 30~35 | 30~35 | 40~45 |
| Sony Studio Lot | 60~65 | 45~50 | 45~50 | 60~65 |
| Long Beach | 55~60 | 35~40 | 40~45 | 55~60 |
When using RG8-U cable, there was very little drop in signal strength with both Sharkie and Wisycom. There were slight variations with both Lectro and Shure, being ±1 dB away from ideal gain.
Maybe this is an attestment to go for the low-loss cables, and just handle the ordeal of unwrapping and rewrapping these beasts. But the Sharkie held its ground, even when using the less-shielded RG8-X cable. And with 1 dB increment control, the Sharkie’s amp can be set to a gain that fits your needs.
Test 4: Maximum Distance Before Signal Drops, 0 dBuV
| Betso Sharkie |
Lectrosonics ALP650 |
Shure UA874 |
Wisycom LBNA |
|
| Downtown LA | 200~250 ft | 150~200 ft | 100~150 ft | 200~250 ft |
| Joshua Tree | 300+ ft | 250~300 ft | 250~300 ft | 300+ ft |
After the initial cart mast test in Downtown LA, we had the subject walk away from us until we heard the first signal drop or “hit”. Even though we were surrounded by tall buildings and radio towers, the Sharkie performed surprisingly well, even when the subject turned the corner and stood behind a building.
We repeated the same test in an open uninhabited desert patch of Joshua Tree, CA, where there is very little nearby UHF interference in general. We capped the walking test at 300 ft, or 100 m, because anything past that would be unrealistic in most productions… but still good to know!
Other notes
The low-profile BNC port and mount thread placement on the Sharkie’s amplifier can be beneficial or awkward, depending on your mounting setup. For example, when we used K-Tek’s Shark antenna mounts, or directly onto a riser stand, we ran into some installation hiccups:
K-Tek’s mounting rings cannot fully revolve to insert into the Sharkie’s amplifier mount, without its thumb tightener hitting against the bottom fin. This may require some custom workarounds to ensure the bolt threading “catches”, and tightens inside the Sharkie enough for proper mounting.
Additionally, some BNC connectors/boots may be too long, and may be pressed between mast and Sharkie BNC port. This can be resolved using a BNC right angle adapter, and any potential dB loss from using this extra connection can be compensated with the amplifier anyway.
During very windy days, the Sharkie’s skeletal design prevented my antenna mast from becoming a sail. While working on a reality TV show, it started to lightly rain on the fins, but the Sharkie’s construction kept them performing smoothly.
Putting the shark back in sharkfin
Betso has engineered fantastic professional audio tools over the years, such as their SBOX timecode box, and the Sharkie is no exception.
There are several active LPDA fins to choose from, all selling at different price points. But when you consider the Sharkie’s super quiet operation, reliable all-weather construction, and versatile performance, the MSRP of $579 USD is worth every penny. Other sound pros may initially lose interest by the price tag, but compare it to a pair of other active fins that have integrated amplification, and it fits right in the middle.
No matter if working on a soundstage, live venue, or on top of a hill surrounded by radio towers, our pair of Sharkies swam through the noise to chomp every bit of transmission it could.
Silent, sleek, and robust, Betso’s Sharkie is a LPDA fin that finally lives up to its predatory nickname.
~
Want us to test and review more production/location audio stuff?
Drop us a line anytime at info@bamfsound.com !