[R-390] 2 Dud Mechanical Filters Needed

[Graham Baxter]

Hi Keith

I found that the rebuilt ones were very close in attenuation to good
untouched ones. I am fortunate to have two EACs here. One has three
out of four rebuilt filters. The other has all originals and they are
all good. The position of the IF gain pot for the reference -7V at the
detector at 150uV in is almost identical on the two modules.

I am under no illusions, I consider myself fortunate to have succeeded
three out of three times. However, I would think that you would have
to be very unlucky not to improve a filter with 20dB more loss than it
should have. Have a look at the state of the foam. Once it gets
between the disks it spoils everything. And if you have to rewind the
coils, don't forget you can have more than one attempt. Its not nearly
so frightening as it looks!

Good luck

Graham
G8OAD

On 25/08/07, Keith Densmore <densmore at idirect.com> wrote:
> Hi Graham,
> Congratulations on the excellent work you have been up to.
> I have run into a problem with 2 and 4 KCS filters that are working but
> about 20 db more deaf than the 8 and 16. (On several sets) How does the
> input antenuation fair when you have rebuilt one? OK, say you take one of
> your rebuilt 2 or 4's --for the same signal level, how do they compare to
> the 8 or 16?
>
> I also notice the passband ripple on all the filters is pretty severe. Any
> comments.
> I'll let you know if I come up with any 'inards'
>
> 73,
> Keith, ve3ts
> ----- Original Message -----