The 404 MHz required is already available at the output of the subsequent quadrupler. An etched 2-pole filter provides the filtration. Their input and output impedance over a wide tuning range is 50 ohm. The correct dimensioning of the amplifier stages is important here. Thus only the amplification which is actually necessary should be used.
Any excess increases the spurious transmissions present to an extent which is out of proportion.
The mixer is controlled through an attenuator, which should provide an intermediate-frequency level of no more than 1mW at the ring mixer. The attenuator must be dimensioned on the basis of the output available from the synthesiser. Table 1 shows the resistance values required for the attenuator in relation to the synthesiser power level. All the values are based on the standard values from the El2 to E24 ranges. This low-noise transistor stage provides the necessary intermediate frequency amplification.