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New national rf ndb-3 rf milliwatt meter
This RF Milliwatt meter was bought for my HF lab. It ended up not being used and since all my HF equipment have been sold i'm hoping that this unit will find a new home.
Below is the product description from http:// /NDB-2.htm
National RF s Type NDB-2 and NDB-3 RF Milliwatt Meters are affordable pieces of test equipment for both the RF laboratory and the home experimenter. Both provide a digital reading of RF power in dB reference 1 milliwatt of power into a 50 ohm load (i.e. 0 dBm). The circuitry consists of a low noise logarithmic amplifier that drives a digital A/D converting meter circuit. The lowest power levels that can be read are about 73 dBm (approximately 40 microvolts or .00000003 milliwatts). The maximum power input should not exceed 10 milliwatts (+10 dBm or .010 watts) when inputed without attenuation. An internal attenuator is provided and described in the next section.
All controls are located on the front panel. Power is provided by six AA size batteries, which are housed inside the unit. In addition to measuring RF, the Type NDB-3 provides a separate DC output signal, which is scaled to 10 millivolts per dB. Thus, when the meter is used with a swept signal source, such as would be used when sweeping a filter, a useable scope display with a known, convenient logarithmic scale response is provided. Related to this output is selectable filtering, which is used in conjunction with the sweep speed of the swept generator. Both types have a Low Battery level display, alerting you to when battery replacement is necessary for proper calibrated readings. A 20 dB front panel selectable Pi-pad attenuator is provided as well on the input circuitry. When this function is selected, a maximum of 250 milliwatts (1/4 Watt) can be inputed continuously, and Watt for short periods of time.
Specifications Common to Both Types NBD-2 and NDB-3
Maximum RF Input (0 dB attenuation)
(Internal 20 dB attenuation selected)
-73 dBm, nomimal, minimum input level
+24 dBm, nomimal (1/4 Watt), Continuous
6 AA size batteries, internally housed
4 in. Width X 5 in. Height X 3 in. Depth
Specifications Unique to Type NDB-3
Logarithmic DC output level, scaled to 10
1 KHz and 10 KHz (nominal) single pole low pass filtering, front panel selectable
