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Mike:

Thank you for your emails. I agree it would be great if the capacitors at 850 Mhz were adjusted to something less than half of their range, I could just install the same size coils as in the 450 Mhz LPF and retune the capacitors.

Looking at an old 1994 DB Catalog, the curves for the VHF, UHF, and 800 Mhz LPF's are identical. The 800 Mhz LPFs' are not in the 1993 Db Catalog.

I did considered padding the capacitors if their values were different. I assumed Q of the circuit would change with the size of the capacitor and that would affect the response of the low pass circuit.?

I can not see any component identification on the capacitors in either LPF that shows their manufacturer or value. Just looking, they kind of look like Johanson. I have pictures inside both of the LPFs.

I have a capacitance meter with tweezer type probes. It was difficult to get a consistent readings. Besides, since I am not unsoldering the coils, I am actually measuring some overall capacitance value for all four of the capacitors connected in parallel which I expect would not be affected by the inductances of the coils because the measurement frequency is pretty low. I can't say it is that accurate since it is not a very expensive capacitance meter.? It did read something.

I was just hoping that someone might have replaced a capacitor after a lightning strike or something similar, and knew the value.

I may just start by reproducing the UHF coils and install them in the 850 Mhz LPF, then use the spectrum analyzer and see how low I can bring the knee of the filter and pad it if I can't reach 450 Mhz.? The UHF coils look like they are expanded and mashed as part of the tuning.

Micheal Salem

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