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Year 1963 - 129.00 US$ |
WHAT IT IS...
 | The Model 34-NB noise blanker is a solid-state noise blanker to be used in any TR-3 or TR-4 transceiver. |
| Unlike noise clippers or limiters commonly found in communication equipment, the 34-NB is an advanced noise blanker which actually mutes the receiver for the duration of the noise pulse. Between noise pulses, full receiver gain is restored. (The receiver AGC is affected only by the desired signal strength, not by the noise at the antenna.) |
| The 34-NB is most effective on strong, periodic noise impulses such as ignition noise. The blanker is least effective on random noise. This noise is continuous in time and the information it masks cannot be recovered by either blanking or limiting techniques. However, loss of communications due to random noise is a rare occurrence, generally impulse noise is responsible for such situations. |
| Low level signals masked by noise impulses without the noise blanker can be copied when the blanker is used. The 34-NB is a must for the mobile operator because he can now blank ignition noise due to trucks and other cars as well as his own car. |
HOW IT WORKS…
| At the output of the receiver mixer, the signal follows two paths. The main signal path is through a delay circuit, an amplifier, the gate, then to the crystal filter into the I.F. |
| The balanced gate is a noiseless electronic series switch that opens for noise impulses but closes to allow the signal to pass. |
| The other path is through the noise processor. Here the noise pulses are converted to 2.15 MHz, and travel through an amplifier into the gate driver, which opens the gate at the instant each noise pulse enters it, on the way to the receiver I.F. The noise is stopped before the highly selective crystal |
| Filter causes the pulses to lengthen and mask more of the desired signal. |
| The kit consists of these main parts: 9-NB board (composed of 17 transistors, 4 diodes and associated circuitry), NB board, capacitor assembly, switch assembly, lever knob, and miscellaneous hardware. |
| Installation of the kit is about a two hour job for the competent technician only. It requires use of the usual hand tools, plus soldering iron and electric drill. |
