[R-390] Filters

[Bob Camp]

Hi

If you have continuity, the coils are still there. A coil is either open / shorted / or good. A single turn shorted *could* create an issue that is very hard to diagnose without a Q meter. Filters that die with good coils likely have trouble from mass loading (goop on the disks) or  from coupling (broken wire between the disks).

Bob

On Feb 16, 2013, at 3:09 PM, Graham Baxter <graham at delphe.co.uk> wrote:

> There does seem to be a lot of interest in the doughnuts at the expense of
> the intriguing physics of the filter!
> 
> It is my recollection that the filter was completely symmetrical. If you
> can't see the wire, it is probably broken. That is sad news, but hopefully
> someone will be able to supply a filter with bad coils but intact mechanics.
> 
> Graham
> G8OAD
> 
> On 16 February 2013 19:55, quartz55 <quartz55 at hughes.net> wrote:
> 
>> I get the feeling like no one is really reading my posts so I may quit
>> dealing with it, too bad for someone that wants to rebuild filters.  But I
>> will post pictues on my photobucket account for anyone that is interested.
>> 
>> Here's a picture of what I think is the center wire attached to the second
>> resonator disk on the top (output) end of the filter.  On the bottom end
>> (input), I don't see the wire like that, but I have not yet pulled out the
>> coils on that end, the center wire may be coming off the end disk there and
>> that's why I don't see it in the resonator disks.
>> 
>> 
>> http://s251.beta.photobucket.com/user/DogTi/media/R390A/filtertopcenterwire_zps1e973e91.jpg.html?sort=3&o=0
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