Elecraft KRX3 User Manual download pdf (Page 33)

Enter the FREQ OFFSET shown on each filter. The optional 8-pole filters have no offset

marked on them. Enter a zero in the FREQ OFFSET column for those filters. On the 5-pole

filters the frequency offset may be negative, indicated by a minus sign (single dash) ahead

of the number.

Table 1. Installing Crystal Filters.

Install the filters on the KRX3 board as shown

in Figure 38. Use the screw and lock washer supplied with

each filter. Refer to the list of filters you created in Table 1 to ensure each filter is installed in the proper

position. Four of a possible five filters are shown installed on the KRX3 board in Figure 39.

CAUTION

1) Do not use screws longer than 1/4” (6.4 mm) to mount the filters. Use your rule to

measure the screws before installing them. Longer screws may extend into the optional

8-pole filter and destroy it. We strongly recommend you use a screw no longer than 1/4”

(6.4mm) even when installing the 5-pole filters to reduce the possibility of damaging an

8-pole filter should you change them later.

2) Do not over-tighten the screws. Too much torque may pull the threaded bushing out of

the bottom of the filter module.

Figure 38. Installing Crystal I.F. Filters.

FL1 is to the right and FL5 is to the left. In the next step you will install the filters right-

to-left on the KRX3 RF board as well.

POSITION FL5 FL4 FL3 FL2 FL1

BANDWIDTH

FREQ OFFSET

1. If you’re installing the K-FL3B FM filter, place it in FL1 position since it is the widest

bandwidth filter available.

2. The bandwidth is shown in the label attached to the filters except the K-FL3B FM filter.

Record a bandwidth of 13 kHz for the K-FL3B FM filter.

3. All of the optional 8-pole filters have an offset of zero. Note that the 5-pole filters may

have a negative offset, indicated by a minus sign ahead of the number.

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Elecraft KRX3 User Manual Page 33