Monday Morning Coffee and Technical Notes

January 12th 2026 View as Webpage

  Copper Thefts

Copper theft at broadcast transmitters has cost stations thousands of dollars and continues as copper prices rise.

Unattended, remote transmitter sites are frequent targets. Store spare copper items securely and ensure sites are fenced and locked.

Consider installing security cameras with motion alarms that send alerts if intruders are detected, as these systems are now more affordable.

ABA Engineering Academy

The ABA Engineering Academy will host the Radio Engineering Class from February 23–27, 2026.

A few seats are still available so sign up now.

These free classes, held at the ABA Training Center in Hoover, AL, offer both an introduction to broadcast engineering and a refresher for experienced engineers, covering topics such as electronics, audio, video, RF systems, antennas, studio operations, and FCC Rules.



Attendees may take the SBE Certified Broadcast Technologist exam on Friday (exam requires a separate fee and is optional).

For schedules and registration, visit the ABA Engineering Class website.



The Television Engineering Class runs March 23–27, 2026.

January ABA Engineering Webinar

The first ABA Engineering Webinar for 2026 will be held on Tuesday January 20^th, 2026. It will feature a discussion concerning recent cyber-attacks on radio stations and ways to help prevent these attacks. Special guest will be Wayne Pecena, IT director Texas A&M University. Click here to register.

The February webinar is scheduled for February 17^th will feature Cris Alexander with Crawford Broadcasting, discussing the monitor point requirements for AM directional stations.



These engineering webinars are offered on the third Tuesday of each month and feature various guest speakers covering technical topics of interest to radio and television engineers.

FCC – Licensed Power Levels

Engineers know the FCC sets output power limits for stations. Licensed levels and measurement procedures differ by service type. Below is a summary of these requirements.

AM (non-directional)

Measurement is normally made by observing the antenna current at the feed point to the antenna. 

The formula is P = I² x R or I = √ P/R, where P is power, I is the antenna current and R is the antenna resistance (listed on the license).

AM (directional)

Measurement is normally made by observing the common point current (at the input to the phasor system). Use the same formula as with non-directional system.

FM Stations

FM stations have two different procedures available. One is the direct reading, using a calibrated watt meter place in the transmission line at the output of the transmitter. The key word here is “calibrated”.

Indirect reading of the power is accomplished using the formula P = E x I x efficiency, where P = power, E is plate or supply voltage, I is plate current or supply current and efficiency is determined by the transmitter manufacturer.

TV Stations

Power measurements for television transmitters are the easiest, using a calibrated RF power meter plugged into the monitor port of the transmission line at the output of the mask filter. Don’t forget to set the meter sensitivity using the insertion value listed on the transmission line port.

Output Power tolerances are 90% to 105% for AM and FM Radio and 80% - 110% for television.

Back to the Basics – FM Combiner Systems

The heart of the modern balanced combiner system is the quadrature hybrid. Each station module employs two hybrids, one on the transmitter input(s) of the module and one on the output/broadband portion of the module.

In a FM balanced combiner system, the input hybrid (a 3 dB coupler) splits the input power into two equal halves sending one half to each filter leg, allowing the signals to recombine later while providing high isolation for unwanted reflections.

Because of the electrical length of the hybrid, the signal exiting Port 4 is 90° degrees out of phase with the signal exiting Port 3. When a hybrid is used as a combiner the exact opposite happens and two signals 90° out of phase are recombined into a single signal.

 Typical values of insertion loss range from 0.2 dB to 0.8 dB depending on number and size of the cavities, channel separation, etc.

The filter cavities are used to minimize the creation of Intermodulation distortion by isolating the different radio frequencies from each other.



Intermodulation distortion is the result of two or more signals interacting with each other to produce an unwanted signal. This can happen in the output section of transmitters if not properly isolated.

Pro Audio – Understanding a Matrix Buss

 A bus in mixing is simply a channel that receives audio from multiple tracks and combines them into a single signal path. Think of it like a subway line—individual passengers (audio signals) from different stations (tracks) all board the same train (bus) to reach a shared destination, whether that’s a master fader, an effect return, or another part of your signal chain.

Matrix mixing revolutionizes audio routing by enabling the creation of separate mixes from multiple sources. A matrix mixer allows for effortless direction of signals from diverse inputs, even other buses to different outputs, thus establishing a logical and practical signal flow. This is particularly beneficial in live sound production, where the need to create separate mixes for different purposes is paramount.

Matrix mixes can be employed to send separate mixes to various rooms in a venue, providing greater control over the sound in each space. This is particularly advantageous for venues with multiple rooms, as it allows for different mixes to be dispatched to each room, catering to the specific needs and preferences of each area.

This method is also useful for creating a mix intended for streaming or broadcast media. The balance in the front-of-house (FOH) mix usually differs from what is needed for a media or streaming feed.

No Earl you can't use that to replace your grandaddy's still!