Banned wireless Mics

[tjsilva]

Have the oppurtunity to pick up some wireless mics for cheap, but it is not worth it unless I can somehow modify the frquency at which they operate. They are operating in the banned 700mhz band. Anyone ever try this before? Any ideas?

[g1]

You would have to get into a completely different frequency BAND. If it is even possible it is not economically feasible. If it could be done for a reasonable cost, the manufacturers would be doing the modification. Have you contacted the manufacturer or an authorized service center?

[olddawg]

Is it for resale or personal use? If it's just a couple for personal use and they are really cheap, they only have a range of a couple of hundred feet. I doubt the FCC will hunt you down. And even if they do just act stupid. Lots of us used to put big linear amps on CBs. There's banded and petty. But if you sell them look out.

[g1]

they only have a range of a couple of hundred feet. I doubt the FCC will hunt you down.

I would agree with this but we are assuming the interference is only a one way thing. What if they are unusable because the receivers are picking up too much garbage?

[J M Fahey]

Get your money back and forget them.
Their sale was forbidden by January 15, 2010 so whoever sold you them committed an illegal act.


Your friendly FCC says:

Using the 700 MHz Band for a wireless microphone (or similar device) could be extremely dangerous and could even be life threatening. Police and fire departments, and other public safety groups, use frequencies in the 700 MHz Band. Interference from wireless microphones can affect the ability of public safety groups to receive information over the air and respond to emergencies. Harmful interference to these communications could put you or public safety personnel in grave danger. In addition, use of your microphone can cause unlawful interference to consumer services provided using the 700 MHz Band.

Operation of wireless microphones in violation of these rules may subject the user to substantial monetary forfeitures and/or criminal penalties, including imprisonment. Because any operation in violation of these rules creates a danger of interference to important radio communications services and may subject the operator to severe penalties, this advisory emphasizes the importance of complying strictly with these legal requirements.

[Enzo]

I'd agree with Fahey, but I would add this. With the DTV changeover certain bands were re-assigned. SO some wireless bands became obsolete. The band is now reserved for some other use. However, if no one is using that band where you are, no one would know you were there. The things do have a very limited range, and the FCC gets involved when someone interferes sith someone's rightful band. That is the reality. If you are using wireless mics at some bar along a country road, no one would likely ever know. However, if that band is now the local ambulance communication channel, then they will not be very happy when they start hearing your Credence Clearwater impressions.

[tjsilva]

I think I will just forget about them, I haven't purchased yet. I told the seller they where now illegal to use and offered 10 bucks just so i could take them apart and check it out, needless to say they didn,t respond.

[km6xz]

You could monitor the band and log what channels are being used and them change their carrier frequency. If they are old, they would need a crystal change in each unit but newer units have a master clock crystal and use a synthesizer to generate local oscillator and exciter signals for the receiver/transmitters. See if someone has a spectrum analyzer covering the band and have them monitor and detect any signals and note their frequency. For any given area, 99% of the spectrum would be unused.
I would only consider it even worth while if they are quality units, not some junk Nady's or such. If they are well engineered it is worth it.
I've been importing wireless audio systems for tour guides from China made to my spec and they operate in that band but only used in Eastern Europe. I got them certified so they are legal. Buying several thousand still cost $60 for each receiver each so they are not junk. I rent them for $3 a day to tour operators. Larger tour groups in some museums are required to have wireless audio systems and mine are $1 less than anyone else.

[Strat]

For you guys still having the 700 Mhz wireless units and wanna dispose of it, try selling them to asian countries....the band is still legal over here....

[jrfrond]

Technically, it's illegal to use any of the old 700mHz wireless units. As a Sennheiser service center, we must refuse to service any "C" band units, and refer them to the Sennheiser customer service line. ll of the major wireless manufacturers offered pro-rated exchange programs initially, but they have been over for awhile.