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RF-Links SPX-68S Transmitter Review


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#1 Robert Starling SOC

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Posted 01 March 2007 - 01:23 AM

I just purchased a RF-Links SPX-68S transmitter and had the opportunity to compare it today side-by-side with a Modulus 3000 I had on rental.

I compared it using a professional four antenna quad diversity receiver on set (outdoor tennis stadium) and a el-cheapo handheld $149 7" LCD "Directors monitor". Basically, there was no difference in the signal or reception with relation to distance or obsticles; they both looked equally good or bad however you want to put it.

The 68S is a nine channel (61-69) unit so the Modulus beats it there and clearly the Modulus has it beat in design and "apparent durability". As in it looks more professional and durable that the RF-Links unit.

On the flip side, the RF-Links unit cost under $700 USD, plus $50 for the Hirose cable.

Mike Wilder at Image Gear was super helpful and very responsive. The only problem I had was they sent the wrong connector for my Steadicam sled but he got me the pin configuration within hours so I could have the fix done locally.

Not a very scientific test and who knows what RF demons lay ahead with regards to shielding, spurious harmonics and interference but so far it seems to be a good starter unit and hopefully will last long enough until the new 4000 if it ever comes out or the Canatrans.

FWIW...
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#2 Dan Coplan

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Posted 02 March 2007 - 12:47 PM

I may as well chime in since I also have an RF Links unit, though mine is the SPX-68G. My review is the same as Robert's. I tested it side-by-side with a Modulus 3000 and performance was practically identical.

Pros of the SPX:
Affordable!
Brand spanking new
You can actually get someone on the phone if there's a problem

Cons:
Far fewer channels, but they're in the higher end of the spectrum. I don't know much about UHF transmission, but I'd be awfully surprised if one of the channels didn't work just fine no matter where you are (not including interference that would wipe out any broadcast signal).

I disagree with Robert about the design and durability. I suppose the Modulus looks cooler with its dials and heat sink but the SPX is a small, mysterious black box that looks plenty durable and professional to me.

The difference between my 68G and Robert's 68S is that the 68G has 5 channels rather than 9. The channels are changed via a small inset pot that you dial back and forth to tune in. Minor pain but the advantage is you can tune in to both NTSC and PAL.

RF Links does, by the way, make a unit that covers 50 UHF channels, the GX-68 and GX-68/H (high power). These cost around the same as a Modulus, I believe.

RF Links: http://rf-links.com/video_senders.htm

I had customer service issues with the guy at RF Links. Personally, I didn't get a good feeling for him and his policies blow: No trial allowed and a ridiculous 25% restocking fee to return one. But Mike Wilder at Image Gear, which I suppose is a distributor for the RF Links products, is great. He's always responded to my emails, called me back, and said I could try the unit out with a no hassle, no restocking fee policy.

Image Gear: http://imagegearinc.com

If any of you check them out, tell 'em Dan and Robert sent you!

Dan
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#3 Brad Grimmett

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Posted 02 March 2007 - 03:13 PM

I see one issue with this transmitter. If you use a Bartech you could have problems. I had issues when broadcasting on my modulus at high channels while using my Bartech. I'm not technically savvy enough to know what the issue was, but Jim Bartel told me that there can be interference issues when using high channels and the BFD. Please correct me if I'm wrong Jim. I just wanted to point that out for folks so they can avoid any future problems. Otherwise, it sounds like a good transmitter.
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#4 Robert Starling SOC

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Posted 03 March 2007 - 05:14 AM

I see one issue with this transmitter. If you use a Bartech you could have problems. I had issues when broadcasting on my modulus at high channels while using my Bartech. I'm not technically savvy enough to know what the issue was, but Jim Bartel told me that there can be interference issues when using high channels and the BFD.


I think the BFD manual mentions something about this high channel issue but in the last two days of operating pretty much all day with my Bartech I have not seen a problem... yet. I also am mounting the transmitter low down on my sled quite a bit away from the BFD. I'll test it up high this near the BFD or camera.

Jim would be THE MAN for the answers.

Thanks!
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#5 JimBartell

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Posted 03 March 2007 - 03:02 PM

The problem with the Modulus interfering with the BFD when using high (>50) channels isn't due to the channel the Modulus is supposed to be transmitting on, it's the OTHER channels it's also transmitting on. Set a Modulus on 32 and you will also pick it up on a channel in the 50's as well. It is these unintended transmissions that cause problems. When the Modulus is set to 50 and above it is also transmitting on a higher frequency as well (80's?). It's these unintentional transmissions that overwhelm the BFD's RF receiver. If the RF-Links unit only transmits on the channel that is selected it should be no problem.

Jim "it only hertz when I laugh" Bartell
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#6 Robert Starling SOC

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Posted 03 March 2007 - 07:23 PM

If the RF-Links unit only transmits on the channel that is selected it should be no problem.


At under $700 my guess it's probably not the cleanest signal out there and the truth is ALL transmitters and antennas create and produce spurious harmonic signals. Some are just cleaner than others and there is a huge range. Something as simple as one little piece of wire or circuitry inside one device can become the perfect antenna for a specific frequency or it's harmonics from another device.

Jim, what happens to a BFD with interference? Ghost focusing or erratic behaviour? Nausea, muscle pain, headache, dry mouth? ;-} Email a few ideas for tests and I'll torture it with the RF-Links during some down time.
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#7 Alec Jarnagin SOC

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Posted 04 March 2007 - 12:29 AM

Robert,

The Modulus 3000 is a particularly dirty transmitter. It gets decent results but it does it by blasting all over the place. If set to >50 & placed close to a Bartech receiver (varies, but usually within a few inches) the result is a simple error light on said receiver. Fairly obvious stuff (no hidden gremlins; it works or doesn't - at least in my experience). I'd try your cheap transmitter (at home) at various lengths from your Baretch. I bet you will be pleasantly surprised.
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#8 JimBartell

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Posted 04 March 2007 - 01:14 PM

Robert,

The Modulus 3000 is a particularly dirty transmitter. It gets decent results but it does it by blasting all over the place. If set to >50 & placed close to a Bartech receiver (varies, but usually within a few inches) the result is a simple error light on said receiver. Fairly obvious stuff (no hidden gremlins; it works or doesn't - at least in my experience). I'd try your cheap transmitter (at home) at various lengths from your Bartech. I bet you will be pleasantly surprised.


What he said. Those rumors of sterility and genetic mutation were totally exaggerated.

Jim "now if I can just get someone to build BFD's for me" Bartell
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#9 Chris Konash

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Posted 04 March 2007 - 03:20 PM

Jim,

I'm just wondering when your going to put the BFD machine on auto pilot to kick out a few systems a day, so you can turn your attention to making a well built RF transmitter for our community. I'm sure with your customer service record you wouldn't be able to keep them on the shelf either. Actually you wouldn't need any shelves as the BFD also sell as fast as you can build them. I'll keep thinking up these ideas if you can do all the work to make them come true.... haha

Chris Konash
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#10 JimBartell

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Posted 05 March 2007 - 01:38 PM

Jim,

I'm just wondering when your going to put the BFD machine on auto pilot to kick out a few systems a day, so you can turn your attention to making a well built RF transmitter for our community. I'm sure with your customer service record you wouldn't be able to keep them on the shelf either. Actually you wouldn't need any shelves as the BFD also sell as fast as you can build them. I'll keep thinking up these ideas if you can do all the work to make them come true.... haha

Chris Konash


Believe it or not I Know very little about RF design. I purchase all the RF parts of the BFD from another company that specializes in RF products. I just buy the parts I need and plug them in.

And if I do ever figure out a way to "put the BFD machine on auto pilot to kick out a few systems a day" you'll find me on the beach with a cold Corona, or, alternatively, raiding Ron Baldwin's new kegerator while he's working.

Jim "not gonna work on Maggie's farm no more" Bartell
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