Click here to see how to correctly set up your audio from the source to the transmitter.

Another alternative to the included AM1000pr audio interface, it is possible to use the MCM electronics 555-8485 as an unbalanced to balanced interface, let us know and we will provide the connectors/wiring you need to use this device at only a slight cost increase ($25). We also stock this device.

Click here for AM processing article

Click here to see how to connect the Innovonics 222.

Important: If you are using an Inovonics 222 or other processor capable of driving the AM1000 beyond 100% positive peaks be sure to get the polarity of the output balanced audio right, otherwise the processor will be trying to drive the peaks negative which will result in distortion.

Customers report that there are surplus units like the CBS Volumemax available that will produce great results with our unit.

Here is how to tell if your polarity is right:
1. Turn the positive peaks all the way down.
2. Turn the output level up until you get distortion, then back off a little (hair) for good sound.
3. Then turn the positive peaks all the way up, if you get distortion then the (output) terminals + and - are probably reversed.

The polarity of the input terminals doesn’t matter.

Audio Processing:

The Innovonics 222, 235, Optimod, and other radio station type audio processors are different from a standard audio processor intended for general audio applications. A standard audio processor like a Autocom Pro MDX 1400 can add compression and limiting can improve your sound, but it can’t approach the what a audio processor designed to drive a AM transmitter can do. The reason is an old AM trick developed in the late 70’s called asymmetrical modulation. A big word, but all that means is that instead of the wave form being balanced, or equal around the ground, it is more positive. The waveform is not symmetrical, it is asymmetrical. This has the effect of making your sound louder (punch trough static) and makes it possible to modulate the transmitter to a higher peak power legally. If you can find an Audiomax or Volumnmax am transmitter type audio processor it can work well for you, they were popular in the 70's and 80's.

RangeMaster is the only certified AM transmitter capable of asymmetrical modulation.

Single chip audio processors found in real estate type transmitters don't offer much performance, you are much better off with at least an Autocom Pro audio processor or equivalent.

See this document to set your modulation level with a scope.

See for an inexpensive modulation monitor, (will monitor your radio waveform output) the unit can work with Part 15 transmitters.

Ground Loops:
The audio interface provided with the RangeMaster contains a powered +/- adjustable 6DB audio amplifier. While the output of the device is isolated, the input is grounded thru a resistor. If you are experiencing hum, you may have a ground loop here (or elsewhere).

The resistor (this resistor can be shorted by a switch, see adapter instructions) between the grounds of the audio interface should prevent any ground loop, but if not Ground loop isolators are easy to find. Radio shack has one. Cheaper units can be found on
Just do a search on "ground loop isolator" and many choices will come up.

Another way to remove hum are to use a grounded power supply (you can get one at Radio Shack) A grounded supply will have a third ground prong on the power cord. The transmitter can operate with a supply rated .5 AMP in the  12-18 volt DC range though it is better to use a supply above 14 volts. Be sure to ground your shielded cable at one end only, don't run the audio cable near any AC power cords.
Good grounding means connecting all grounds together at one point instead of multiple paths.
A hum is either induced into the audio wiring by nearby AC power cords (move or shield the audio wire), or from improper grounding, or can come in from the power supply (use a shielded grounded supply).
A proper ground system will bring all grounding for all components to one point, then at that point take the connection to the earth. Hum can come from ground not really being true ground, but some potential above ground.

Radio station DJ software for the PC:

See for a great program scheduler system. (free)

Also see (not free)

We have heard that Sam Broadcaster is good software.

There are many ways to put audio on your station, depending in your goals. From a radio DJ scheduling software, to as simple as a $20 MP3 stick player.

The iPod shuffle is a great choice for your MP3 player audio source, just load your MP3 files, and set it to repeat. Be sure to buy the "on the go" power supply with it, you can get 110v AC or 12VDC adapters.(Amazon)

The audio spec for the RangeMaster is +/- 3db 20-20Kz which is typical for a high performance unit, this can be increased even further with our hi-fi option (call, see contacts) This spec can be improved to +/_ 2db

See this link for a high performance unbalanced to balanced link that could replaced our AM1000PR adapter for high performance applications. Premier Technologies has an easy to use high quality MP3 player designed for the "music on hold, store music" industry.
New! RangeMaster is now a dealer for the quality Premier Digital player Line
USB 1100 – The only available Premier unit that downloads MP3 files directly from a USB flash drive (thumb drive) for Music on Hold
•    Downloads standard MP3 files directly from the removable USB drive to the internal memory or:
•    Plays standard MP3 files directly from the removable USB drive
•    No special software needed to record new audio on the drive
•    USB drive comes loaded with 6 licensed audio tracks
•    Easy install for the smallest of locations
•    Aluminum casing with external wall mounts
•    Price is $249 with a 256 MB drive
For information sheet click here
We have tested this unit here and it works great! Balanced audio out can drive the transmitter directly or the 8 ohm out can drive the studio interface, your choice.

Racom Inc make an unique easy to use recorder/player, we can ship your RangeMaster with a Racom product if you like. We will do all the interconnect wiring to the Racom product. They offer many different models, see the link above, visit the Racom web site. Pick one you like and call us for your pricing.

You can use one of the many MP3 stick players out there to provide your on air program material. Just load your MP3 files onto it, set it for repeat all, and you are ready to go. We can supply a USB power supply for a MP3 stick or if yours is battery powered, call us for a power supply. We recommend using an MP3 player that has a power supply, or an USB MP3 player with an internal rechargeable battery. We have USB power supplies in stock that will keep your USB rechargeable MP3 player powered 24/7, just let us know you need one when ordering. If you go this route be sure your player will play with the power supply connected, some will only charge.

The transmitter will sound good without and processing, but will sound GREAT with the right equipment!

This is from Bill in California:

I have been on the air now for just over 2 years and I have certainly spent allot of time in quest of the perfect on air EQ. What I have discovered is that in order to have good sounding audio you need a minimum of the following:

1) Proper drive level to your audio chain.
2) Pre-Processing (AGC Leveler/Gain Rider).
3) Main Broadcast Processor.
4) A good transmitter (AM1000 of course)

I got a pretty good sound out of the following:

1) Symetrix 422 (AGC Leveler)
2) DBX 160a (Compressor/Limiter)
3) Inovonics 222 (Low Band Analog Broadcast Processor)(NRSC Compliant)

The best sound that I have got yet was with my current set up:

1) Symetrix 422 (No Leveling, No AGC, being used as a preamp).
2) Aphex Compellor (AGC Gain Riding / Compressor / Limiter).
3) Omnia 3AM (5 Band Digital Broadcast Audio Processor).

The Symetrix 422 costs about $275.00, the Aphex Compellor costs about 1K, and the Omnia 3AM costs about 4K.

The audio coming out of my Sound Blaster Live card on the automation computer is just too low to successfully drive the Aphex Compellor. Also the output of the sound card is HiZ unbalanced. I use a couple of those Radio Shack matching transformers (HiZ Unbalanced <> LoZ Unbalanced XLR) to get the audio signal into the Symetrix 422. I use the Symetrix 422 to boost up the drive audio to around -15 to -12dB (as I said, ACG and LEVELING Bypassed). I then feed the output of the Symetrix 422 into the Aphex Compellor > then into the Omnia 3am > then out to the TX.

I still haven't achieved the PERFECT EQ but I am at least WELL ON MY WAY (>: