8 Pole Crystal Filters for the Drake R-4C Receiver

Noble Radio offers 4 stock filter bandwidths for the Drake R-4C Receiver 2nd IF Frequency of 5.695 MHz. Bandwidths of 1.8K, 450Hz and 250 Hz are standard designs that plug into the rear sockets of the radio. A 2.8K SSB filter is available that replaces the internal 2.4K Drake filter. A 4.0K AM filter at 5.645 MHz is available to plug into the internal AM Filter socket. 

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NR-FL4-4.0

NR-FL-4.0 8 pole Crystal Filter for Drake R-4C Receiver has a form factor that is compatible with the internal R-4C filter socket. The 4.0K filter is designed as a direct replacement for the original Drake AM filter or upgrade from the 150 ohm resistor in receivers without the AM filter. Typical shape factor is 2.0 with an insertion loss of less than 6.5 dB and center frequency of 5.645 MHz

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NR-FL4-2.8

The NR-FL4-2.8 8 Pole Craystal Filter has a form factor that is compatible with the R-4C internal Drake 2.4K SSB filter. The 2.8K filter is designed to replace the stock 2.4 kHz filter for ehanced audio bandwidth . Typical shape factor is 1.7 with an insertion loss of 4.5 dB. Installation of this filter requires some disassembly of the radio and desoldering and soldering of parts. 
Click here for a view of the installed filter.

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NR-FL4-1.8

NR-FL4-1.8 8 pole Crystal Filter for Drake R-4C receiver  is plug compatible with the rear filter option sockets.  The 1.8K filter offers a good compromise for a narrow SSB and wide CW filter over the original 1.5K Drake design. It offers good adjacent channel QRM rejection when used in conjunction with the passband tuning feature of the radios. Typical shape factor is 1.8 with an insertion loss of less than 4 dB . Click here for a view of the installed filter.

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NR-FL4-450

NR-FL4-450 8 pole Crystal Filter for Drake R-4C Receiver.  It has a form factor that is compatible with the rear filter option sockets. The 450 Hz filter offers a good narrow bandwidth choice for CW opertion under crowded band conditions. This filter has a shape factor of 2.0 or less and a typical insertion loss of less than 6 dB 

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NR-FL4-250

NR-FL-250 8 pole Crystal Filter for Drake R-4C Receiver.  It has a form factor that is compatible with the rear filter option sockets. The 250 Hz filter offers a narrow bandwidth choice for CW opertion under crowded band conditions. This filter has a shape factor of 2.5 or less and a typical insertion loss of less than 9 dB