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Usable gap in Block 25?


saadasound
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If I'm reading the FCC guidelines correctly, is it true that there's a section of Block 25 that can still be used? Looks like it's open in the duplex gap (653mhz - 663mhz). 

 

If this is true, is it still worth holding onto or buying some systems in block 25, especially for IFB's where you only need one or two transmitters?

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On 8/4/2020 at 5:16 PM, karlw said:

Keep in mind that along with the 20 mW limit, to stay strictly legal while using those frequencies the units must not be *able to be* tuned anywhere else in the 614-692 Mhz area. 

 


This would most likely only be a problem if you are working in an RF-coordinated environment where someone is assigning you specific frequencies and marking/double-checking your equipment. Outside of that, it would be very difficult to determine both your gear’s power output and ability to tune outside the legal gap unless they’re close someone was close enough to touch it. 
 

Personally, I do just enough coordinated events that it had me feeling a bit uncomfortable about using them entirely, and ended up selling all my b25 gear just to alleviate the potential stress. That’s a decision you’d have to make for yourself. 
 

If you’re interested in being fully-legal to operate in the guard bands, I believe Wisycom and their B7-band of gear are currently the only pro wireless to fully meet the legal requirements. Of course that may change as other manufacturers decide for themselves whether it’s worth the investment to come out with new gear designed to work within those parameters. For what it’s worth, I spoke with reps from 4 different “location sound specific” wireless manufacturers at NAB2019 about this very subject, and at the time all but Wisy said it currently wasn’t worth it, but would evaluate again in the future. 

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FWIW, Zaxcom transmitters can adjust band limits in 6 mHz steps via the Factory Menu. Therefore, a block 25 transmitter can be set to only tune from 656 mHz to 662 mHz. 656 to 657 is part of the 653-657 range available to licensed users and 657 to 662 is within the 657-663 range available to unlicensed users and White Space Devices. In the Extended Menu the transmitter's output can be set to 25mW which in practical use should be within the legal limit.

 

 

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7 hours ago, John Blankenship said:

FWIW, Zaxcom transmitters can adjust band limits in 6 mHz steps via the Factory Menu. Therefore, a block 25 transmitter can be set to only tune from 656 mHz to 662 mHz. 656 to 657 is part of the 653-657 range available to licensed users and 657 to 662 is within the 657-663 range available to unlicensed users and White Space Devices. In the Extended Menu the transmitter's output can be set to 25mW which in practical use should be within the legal limit.

 

 

It's all software – Zaxcom should just release a Block 25 firmware update to set it to the operating range and 20mW output

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