DuneStar Model 504 Bandpass Filter Characteristics

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The DuneStar 504 is a relay-selected bandpass filter array that allows operating two stations on different bands simultaneously--without blowing up your receiver front-ends. This model consists of five bandpass filters, one each for 160m, 80m, 40m, 20m, and 15m. The rig transmits and receives through the proper bandpass filter, which 1), reduces wideband phase noise radiated from the transmitter; and 2), prevents out-of-band power (and noise) from reaching the receiver. A band select signal from a manual switch or the radio selects the correct operating band. Coupled with the band select schemes described previously, the DuneStar filter array is completely transparent in operation. Besides its utility in protecting adjacent receiver’s front ends, the filters also reduces TVI by a small amount (15dB to 20dB). Figure 1 shows the system block diagram of a dual-rig contest station employing autoswitching bandpass filters.

Filter Characteristics

The DuneStar 504 was evaluated with a HP 4396B Network/Spectrum analyzer. Table 1 summarizes the band-to-band rejection characteristics of the individual filters. Oscillographs for each bandpass filter follow.

Filter Oscillographs

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