Custom Equipment - Michael Patton & Associates - Professional Broadcast Engineering

Custom Equipment offered by MP&A:

Retrofit Digital Display Unit for Harris SX-series AM Transmitters: $750

Workling display in transmitter

MP&A now h

as stock from our third production run of our well-regarded retrofit color LCD display for Harris SX series AM transmitters. We saw the clear need for these over the years, as the original alphanumeric displays, made by Texas Instruments, have proven to be terribly unreliable, were declared obsolete by TI many years ago, and have been essentially unobtainium for many years now.

Display showing transmitter type confirmation screen

Even when the original display worked right, using it was cumbersome at best; the display showed only a 2-digit code for each channel/reading, and the user needed to have a chart of channel numbers to have any idea which reading was for what parameter, then go look up the normal readings in the (often lost) factory test data sheet. Our retrofit solves these problems by displaying in plain text the channel name, unit of measurement, and even the usual normal reading, for any channel chosen (Our units have jumpers to select the power level of the transmitter it's in, so it will display proper normal values for that transmitter.) With the original display, to diagnose any overload condition required yet another confusing chart - sometimes even requiring math to decipher the reading! - but our display lists the overloads in clear text.

Retrofit display ready to drop and plug in

Changing to the new display couldn't be simpler: Our display mounts onto the mounting studs of the old unit and plugs into the old one's ribbon cable. You can either reuse the old keyboard, whose wires can be screwed down to matching pins on the new one, or we can supply a new keyboard with the new display.

Click here to see our marketing flier for the Harris SX Retrofit Display: New Life for the SX

Units are in stock for immediate shipment.

Harris SX/Gates combo oscillator board

Replacement Oscillator Board for Harris SX & Gates series AM transmitters: $800*

MP&A now offers a drop-in replacement for the original crystal-controlled RF oscillator board used in all of the SX series and the Gates series AM transmitters, including the 1 kW, 2.5 kW, and 5 kW units. Our board keeps the same basic design but uses modern integrated circuit types for the divide-by-two/four counter and the RF pre-driver/buffer amp. We still use all through-hole components for ease of field repair. There is only one custom-made part on the board (a small RF drive transformer, and we've got plenty of those!)--the rest of the parts are readily available from any of the major electronic parts houses. Our board can use the crystal from your old board, can be supplied with our AM-band synthesizer daughterboard (see below) if you don't have a crystal on the needed frequency, or can be driven from an external RF source.

*Price shown is after trade-in of an original oscillator board from either a Gates or SX series unit; without trade-in, the price is $875.

We have stock - call to place your order!

Retrofit PDM Amplifier Board for Harris SX & Gates series AM transmitters: $1100*

MP&A now offers a drop-in retrofit iplacement for the original PDM amplifier board used in all of the SX series and the Gates series AM transmitters, including the 1 kW, 2.5 kW, and 5 kW units. Our board uses an all-new circuit design but keeps the same mechanical layout, so it is a true drop-in replacement. Our board uses modern plastic-case FETS with screw-in sockets (no soldering needed to change), driven by modern FET driver ICs. We still use all through-hole components for ease of field repair. Our board also uses separate power supplies and fuses for the two sections, so a failure of one section does not take the other section off-line.

*Price after $100 credit for your old PDM amp (as long as it's not physically damaged).

Note: price does not include PDM pull-up board; see below for that price.

We have stock - call to place your order!

Replacement PDM Pull-up Board for Harris SX & Gates series AM transmitters: $275

MP&A now offers an exact copy of the original PDM pull-up board used in all of the SX series and the Gates series AM transmitters, including the 1 kW, 2.5 kW, and 5 kW units.

We also offer it as part of a modification kit for retrofitting PDM amplifiers from early production models of SX series transmitters that had the older non-fused pull-up boards. The kit comes with the pull-up board, all the hardware needed to modify the PDM amp, and detailed instructions for making the mod.

The kit - including the new pull-up board - is $450.

Note: we do not offer any trade-in credit for pull-up boards.

We have stock - call to place your order!

Retrofit PA Board for Harris SX & Gates series AM transmitters: $1900*

MP&A is proud to offer our own version of the PA board used in the SX and Gates series AM transmitters, including the 1 kW, 2.5 kW, and 5 kW units. Our board is essentially a copy of the original, except that it, like the later Gates series PA boards, uses modern plastic-case FETs and so is a true drop-in replacement for these transmitter types. It can also be used in transmitrers that originally used the metal-case FETs (now unobtainium), but with the following caveats: The RF drive level will need to be checked and probably reset (procedure in the tech manual) and, as with the ones from GatesAir, you cannot mix and match the metal and plastic case FETs in a transmitter; if you change one PA board, you have to change them all. Of course, this doesn't apply to any 1 kW transmitter, as they use only one PA board.

*Price after $100 credit for your old PA amp (as long as it's not physically damaged).

Note: price does not include the toroid board mounted on the back. We are working on our own version of that board, too, but for now, you'll have to move your old toroid to the new PA.

We have stock - call to place your order!

Synthesized AM band RF source board: $350

MP&A now offers a small (2.5" x 4") PC board that can be used in place of cut-to-frequency crystals, which have become almost unubtainium, as an RF source for any transmitter. Our board can be powered from any positive DC voltage, regulated or not, from 15V to 37V. Using an Arduino micro-controller to control an Analog Devices DDS (Direct Digital Synthesis) chip, it outputs a square wave, either into a high-Z or a 50 Ohm load, and will produce that signal at 5V or 12V P-P, and can be set to run on any frequency from 100 kHz to 5 MHz in 1 kHz steps, with intuitively easy-to-use rotary dipswitches. The frequency generated can be set exactly with a trimpot. This board is designed to be piggybacked onto our Harris SX/Gates combo oscillator board shown above, but, due to its flexibility in power supply voltage and output level, it can be used in almost transmitter in use today.

We have stock - call to place your order!

SC-1 AM/FM Site Controller:

SC-1 Front Panel

MP&A is proud to offer our first custom-manufactured manufactured product, the SC-1 site controller. Based on an industrial PLC with a touchscreen GUI, this unit is ruggedized for reliable service in the toughest environments, while providing complete control of the RF equipment system at any transmitter site.

SC-1 dual power supplies

For an AM facility, the unit controls and monitors the operation of all RF contactors, and controls transmitter power levels and interlocks, to ensure that the right transmitter is always on-line at the right power level and into a correctly-configured antenna system.

The SC-1 has dual redundant power supplies and extensive protection against surges and lightning. An emergency control panel is also included should the PLC become unresponsive for any reason. Each unit is custom-programmed to handle the unique configuration at your site.

SC-1 Screen Shot

At an FM facility, the controller commands and monitors all motorized coax switches and controls the transmitters' interlocks to ensure that no coax switch is ever commanded to break the load's integrity while under power. At either type of facility, dummy loads are fully interlocked and protected.

An SC-1 can easily be retro-fitted into an existing facility in place of an older or ailing controller, or one with no controller at all, as well as being easily integrated into any new facility.

Call or email today to discuss your needs and how the SC-1 can be custom-configured and programmed to meet the needs of your next transmitter site construction project.

Retrofit Filter Capacitor PC boards for Nautel AMPFET-series high-power AM transmitters:

MP&A has developed several retrofit PC boards to allow modern (read: cheaper) snap-in large power supply filter capacitors in place of the conventional but very expensive computer-grade screw-terminal original power supply capacitors. These new PC boards allow you to replace the old dying filter caps for less than half the cost of conventional parts, with no increase in labor time. Total price depends on exact model number of transmitter to be retro-fitted; $80 per board.