[TenTec] Model 282 filter problem

[Ken Brown]

There are not many parts in those filters. If you draw out the schematic 
by looking at the PCB traces you can reason out which parts could fail 
in a shorted mode, or in an open circuit mode, and cause complete loss 
of signal throughput. (If you do this exercise you will no doubt realize 
that some of the components could fail changing the filter 
characteristic, without making the signal throughput go away 
altogether.) One you have decided which components could cause total 
loss of signal, then consider the likely modes of failure based on what 
you know about the components. I would hazard to guess that them most 
common failure mode of crystals is open circuit, when one lead breaks 
off from the plate on the side of the quartz crystal. For disk ceramic 
capacitors ( that is all I have seen in the Ten-Tec filters) I would 
guess that short circuit would be the most common failure mode, but at 
the voltages and currents these things are subjected to in the IF of a 
radio, it seems unlikely they would ever fail.

You could short circuit the series crystals one at a time to see if 
signal comes back. Of course you will not have the proper bandpass 
characteristic while doing this.

The other possible cause is a failure of connections between 
components.This I would guess is more probable than component failure. 
Reflow all of the solder joints, and make sure the pins are clean. Then 
try again.

73 DE N6KB
> Does anyone have any insight into problems (and solutions) that would cause failure in a Ten Tec model 282 (or any other similar model) crystal filter? When the unit is plugged into its slot (on a Corsair) we get no response. Our next step is to test it on a network analyzer but I felt it would be worthwhile to also get inputs from people on the reflector.
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