DM-1 Deviation Meter

An essential tool for operating at 9600 bps is a deviation meter. The DM-1 is a deviation meter designed for measuring the deviation of FM transmitters operating in the 144, 220, or 440 MHz amateur bands.
For maximum throughput, it’s important that your transmitter’s deviation be correctly set. If the deviation is set too low, other stations will not hear your signal; if set too high, your over-deviated signals will interfere with amateurs operating on nearby frequencies.
People can’t rely on subjective deviation tests anymore, so we’ve designed the DM-1 to provide users with a quick and simple way to make accurate measurements.
People using 9600 baud TNCs will benefit most from the DM-1 because correctly setting deviation for 9600 baud Packet operation is nearly impossible to do by ear. Packet users that are used to the ‘braaap’ sound of the 1200 bps packet burst will only hear ‘white’ noise when using 9600 bps. The DM-1 allows users to correctly set deviation — eliminating excessive retries, increasing data throughput, and increasing channel efficiency.
A unique feature of the DM-1 is that the tuning is crystal controlled, which provides stable measurement and eliminates the need for manual tuning. Two deviation ranges allow sufficient resolution for accurate measurement of voice, data, DTMF, and subaudible deviation. Handhelds, mobiles, and base stations can be checked for correct audio deviation.
The DM-1 comes with a ten segment LED bar display and includes an output for external digital or analog meters, which provide increased resolution. Also included is a low-level, de-emphasized audio output for monitoring audio quality through an external amplifier.
Power is supplied by one standard 9 volt alkaline battery. When battery voltage drops below 5.5 volts, the DM-1 is automatically disabled to prevent erroneous readings.
The DM-1 is small (6.125” W x 4.750” D x 1.377” H), and weighs less than a pound. It can be stored almost anywhere until you need it or it can be left in-line.

DM-1 Specifications

Measuring Frequencies: 147.9 MHz., 222.1 MHz., 444.1 MHz.
Deviation Ranges: ± 1 kHz., ± 5 kHz. full scale
Readout: 10 segment LED bar and provisions for external meter
Deviation resolution (LED): 50 Hz. on 1 kHz. range; 250 Hz. on 5 kHz. range (Greater with external meter)
Accuracy: ± 5% of full scale
Audio Freq. Response: ± 2 dB. from 10 Hz. to 300 Hz. (1 kHz. range), ± 3 dB. from 10 Hz. to 5000 Hz. (5 kHz. range)
Sensitivity (WHIP input): < 100 mV.
Operating power (through): 1 - 100 Watts SWR: <1.3 : 1
Audio de-emphasis: 750 us.
Battery: Standard 9 Volt alkaline
Battery current: 60 mA. typical
Battery life: 6-8 hours typical
Size: 6.125“ W x 4.750“ D x 1.377“ H
Weight: 1 lb.

Product News

DM-1

Timewave is shipping DM-1 Deviation Meters to dealers. Check the Dealers page for a dealer near you.