• I have a filter cavity question for those who are experienced with the
• DB4001-series high band cavities. They're listed as adjustable from
• 148 to 174Mhz but do they actually tune lower into the 2m band?

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Every one I've tuned went down into the ham band.? When stretching the tuning of cavities lower in frequency, aside from running out thread the concern is as the plunger gets closer and closer to the bottom end of the cavity, there is more capacitive coupling which begins to degrade the Q.? Whether or not the extra half inch (or whatever the difference is between resonance at 144 MHz vs 148 MHz) is going to make enough of a change in C to worry about I can't say, but would easy to determine via measurements.

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On the opposite end of the scale, I also ended up with a large quantity of aircraft-band (108-136 MHz) DB4001 cavities, and those went UP to the 2m ham band no problem as well.

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??????????????????????????????????????????????????????????????????????????????? --- Jeff WN3A

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