Mc1590 455 Khz If Amplifier

; T1

Note 1

Note 2

Note 3

Note 1. Primary l20iiH (center tapped)

IdO ai 455 kHz

'Cirr;mT position* of Li and C2 are mtsrchanged

Primary Secondary turns rjTiO 1 3

Note 2 Primary 6.0 ^H

Primary winding = 24 turns ^36 AWG (close wound on

1/4"'dia form) Core Arnold Type TH or etiuiv

(wound over center rap)

i^Jote 3 Primary winding = >8 turns P22 AWG (cftmertappod)

Secondary winding = 1 turn 022 AWG (over-wound at center ot primary}

Fig. 7. High-gain i-f amplifier with wide-range age action. Circuit vaJues are shown for 455 kHz, 10.7 MHz, and 45 MHz;

except modulating large AM transmitters, which hardly anyone does any more. Motorola Application Note AN-401, "The MCI554: A One-Watt Monolithic Integrated-Circuit Power Amplifier," gives more informat ion on applications of this useful circuit. As mentioned, the MCI454 is a relaxed version of the MC1554. and the circuits described apply in almost cases.

I-F Amplifiers

A number of new i-f amplifiers have been introduced recently; many are of great interest to the ham, In addition, one that's been around for a few years takes on a new interest in view of iis recent reduction in i1

The MCI350P is perhaps of greatest interest. It features very high gain at frequencies up to 60 MHz and also includes provision tor very wide-range agc\ Power gain is typically 50 dB at 45 MHz, and age range is 60 dB minimum. It has very low feedback capacitance, thus does not need neutralization in spite of its very high gain. The device is c>esigneci for operation on 1 2V from a single power supply, unlike many of the earlier ICs. The MCI35GP was designed for use in television receivers; however, it's equally valuable for many other uses, such as i-f amplifiers at any frequency up to 60 MHz, Typical gain at 45 MHz is 50 dB; at 10.7 MHz, it's 58 dB, and at 455 kHz, 62 dB# Noise figure at 60 MHz is a respectable 9 dB, but you probably would want io use a low-noise preamp il you were using this i-f amplifier in a microwave receiver, for other applications, this noise figure is more than adequate. Typical circuits for the MCI350P are shown in Fig, 7. Component values are given for frequencies of 455 kHz, 10,7 MHz, and 45 MHz.

Very similar to the MC1350P is the

MC1590G, fd higher-performance version sealed in a metal can for use in military equipment The MC1590G costs S5.60 in single quantity, so you can see that the MCI35OP at S3.75 would be of much more interest in most ham applications.

Either the MC1350P or the MC1590G also makes an excellent video or audio amplifier for any application requiring very wide range age, such as speech compression circuits.

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