Frequently Asked Questions - Wireless

FAQs - Wireless

For a location sound mixer making film or TV content, there have been no changes in the rules. You qualify as a Part 74 user.

You have always been required to have a Part 74 license. This has been the case for decades and has not changed. The new rules exempt NON Part 74 users as long as they keep
their power down under 50mW. These users include churches, education, government, bands etc.

Again, for you as a location sound mixer, the rules remains exactly as they have been for decades. Nothing has changed except we can't use frequencies above 700Mhz anymore. 

If you want to get your license, you can get the form FCC601 from:

You will also need Schedule H and forms 159 and 160 (also found on the above link). 
(four forms in total)

Prior to the new rules, churches, educators, musicians, or theater (anyone not involved in motion picture or TV production) were not authorized users and could not get a license because they were not Part 74 users. Under the new rules, you are exempted as long as you use less than 50mW. This might change because the rules are preliminary and not yet finalized. We will keep you posted.

You cannot qualify for a higher powered transmitter under the new rules and cannot get a license.

There have been NO changes in who qualifies for wireless microphone licenses and how much power their transmitter can have. Only those involved in television broadcast - licensed broadcasters, networks, and people making content for television or motion picture production - can get a license for wireless microphones. They can use up to 250mW. 

People who are NOT directly involved in production for broadcast and motion pictures cannot qualify for a license and, under the new rules, can use wireless microphones
without a license as long as they are 50mW or lower. 

They cannot get a lioense - exactly the same as before the new rules. The only difference now is the exemption for lower powered transmitters. 

If you are involved in TV or movies and want to get your license, you can get the form FCC601 from:

You will also need Schedule H and forms 159 and 160 (also found on the above link). 
(four forms in total)

Yes. No if's, and's, or but's about it. This is not new - everyone was supposed to vacate that band LAST June in 2009. The FCC is getting serious about it now. The loss of this spectrum has been in the works since 1995. If you have gear in that range from Lectrosonics and it is under 5 years old, it may qualify for a frequency change program. It will not be free but it will be less costly than replacing all that gear - even with other brands who offer "rebates" or "trade-ins". 

The SNA 600 will operate well below 500 MHz. It is marked 500MHz because we didn't make receivers below 500 MHz until the great digital changeover of all the TV stations in 2009. The SNA-600 measures lower than a 2:1 SWR (Standing Wave Ratio) from 440 MHz to 600 MHz when the antenna arms are fully extended. Less than 2:1 SWR is considered a standard antenna range measurement. The marked range for fully extended is only down to 500 MHz but the antenna will operate much lower than that.

An HM plug on transmitter was tested with three types of AA batteries. Alkaline batteries ran for 5 hours with a dynamic mic plugged on. Alkaline batteries lasted for 3.5 hours with a Sanken CS1 plugged on with the HM providing the 48 Volt phantom power. New Sanyo rechargeable NiMh batteries, measured at 2500 mAh capacity, ran the HM for 9.25 hours with the dynamic and 7 hours with the CS1. Lithium Eveready AA's were outstanding at 16 hours with the dynamic mic and 12.75 hours with the CS1. Your mileage may vary and in the case of the alkalines, will depend on temperature.

Try using the 21750 phase reverser. URL below.

Click here for #21750 page

This will swap pins 2 and 3 on the XLR and the Oktava should now work. You can also switch the wires on the XLR in the microphone. In either case you will need to switch the phase polarity in the Lectrosonics receiver if you are using multiple mics picking up the same audio source to prevent phasing artifacts.

NiMh and NiCd voltages change very little from 90% charge to 5% charge. The change is smaller than the difference between a new and used NiMh. The change is smaller than a cold and hot NiMh. The change is even smaller than the voltage drop across a slightly dirty battery contact. Because of all these reasons, there is no way of measuring the battery voltage and determining the remaining charge. The LED's are not a good indicator of the battery life of a NiMh. A fully charged battery can indicate red and a nearly discharged battery can indicate green, though that's rare. What the LED's can tell you is when the LEDs are off, the battery is dead. 

If the battery has the capacity to hold a full charge, then the timer is dependable. A good AA NiMh will run an SM at 100 mW for 4 hours. When the timer reaches 3 hours, it is probably time to start thinking of replacing the battery. If you must have battery life readouts and the timer is not satisfactory, then alkaline or lithium disposable batteries are your choice. You can test batteries in the transmitters by letting them run down and stop the receiver timer. This will give you a good idea of what your particular brand of batteries can do. If a battery is low capacity, discard it. It's not worth the danger of accidentally ending up in a high value situation.
Best Regards,
Larry Fisher

The biggest difference between the SRa and SRb receivers is the use of a six layer printed circuit board rather than the original four layer board. This single change reduced internal interference (birdies) to the point that gain could be reduced in multiple amplifiers in the RF and IF stages. In fact, one IF stage was simply removed since it was now unnecessary to the design. In spite of the reduced gain, the sensitivity of the receiver improved overall. As you would expect, intermodulation and overload performance improved greatly with the reduced gain. This improved board was first used by exchanging customers' boards on Block 606 in England as they were having the most problems.

With what we learned on the Block 606 changes, we added the same general changes and the six layer board to all the SRa units without saying much about it for several months. These improved units seemed to work very well and tested much better in production. While shipping the improved units, we went back to the SRa RF board and spent several months re-matching every amplifier and filter in the RF and IF sections. This was necessary because of all the other changes that had already been made. Many small improvements were made at each stage leading to fairly impressive additional improvements overall. One of which was an improvement in sensitivity of more than 6 dB. The last major change was to relocate the two IF filters. We found an optimum location by making up 5 different prototype boards, with the IF filters located in various trial positions with different shields and ground plane configurations. The final result had one IF filter on the top of the PC board and one underneath with a solid ground plane and our usual shielding. This simple change improved out of band selectivity by a huge 30 decibels.

With the improved sensitivity, better out of band rejection, improved intermodulation performance, and the elimination of internal spurious responses we decided to advance the model designator from "a" to "b", thus the SRb. As a service to our customers with SRa units, we offered an upgrade for the difference in retail price between the SRa and the newer SRb. The change in model designator also indicates that we think this is a major improvement in the SR receiver and it encourages our customers to get the upgrade.