Mueller Broadcast Design

T25-35SA Subaudible Tone Decoder

The Mueller Broadcast Design T25-35SA subaudible tone decoder provides a simple and reliable way to detect the 25 and 35 Hz control tones sent by many satellite-delivered program networks. It is entirely self-contained and only requires audio and control hookups to your satellite receiver and equipment to be controlled.

The input is balanced and bridging, with a minimum impedance of 9.2 Kohms. This input is a true differential configuration, meaning that it will not introduce noise or other unwanted signals into your satellite audio. It will work equally well with balanced and unbalanced lines.

The detection circuits are bandpass filters which have a very narrow passband. The unit will detect on frequencies which are up to 3 Hz off (assuming a minimum tone level of -10 dB from program level), but the notch efficiency will degrade severely at these extremes. Normal tone rejection at the output is at least -20 dB, with as high as -45 dB possible if the tones are exactly on frequency.

The input level is not critical. If the output is 0 dBm nominal, the circuits are in the middle of the +/- 6 dB operating window. An easily-adjusted gain control inside the box allows input levels of -15 to +10 dBm. It is set at 0 dBm input when shipped. The output is active balanced at 0 dBm (600 ohms) nominal. Unbalanced output connections are accommodated.


If this unit fails due to manufacturing defect within one year of purchase, we will either repair or replace (our option) your unit at no charge beyond return shipping. We reserve the right to utilize remanufactured parts and assemblies during repairs. Repaired units carry the balance of the original warranty. If you did not purchase this unit directly from us, be sure to include a copy of your invoice to establish the beginning of the warranty period. Units returned without proof of purchase will be serviced based on the ship date to the reseller. We assume no liability whatsoever beyond the purchase price of the unit.

30-day Return Guarantee

You have 30 days from date of purchase to determine whether this unit is suitable for your intended purpose, as we cannot predict every possible application or potential compatibility problem which may arise with other equipment. If you keep the unit beyond the initial 30 day period, you will have made an affirmative determination of suitability for your application and further responsibility on our part is limited to replacement or repair under the warranty terms above. If you decide that the unit is not suitable, return it within the 30 day period and we will refund your purchase price less shipping charges as shown on your invoice.

Technical support is available by phone from 10 AM until 6 PM Monday - Friday (central time) at 708-352-2166. Outside these times you can leave a message and we will call you back as soon as possible, usually within 24 hours. You may contact us by fax at 708-352-2170.

The T25-35SA is built on demand. Please allow 2-3 weeks lead time.

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Mueller Broadcast Design
613 S. La Grange Rd. , La Grange, IL  60525
Phone: (708) 352-2166

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