Topband: FairRite Products 2873000202

[George Taft]

N6RK said:


> Minicircuits coats their cores with "Parylene".  The cores are conductive
> like FairRite73 and are in fact probably similar material.  A long time
> ago, a batch of uncoated cores managed to find their way into a bunch
> of ASK-1 mixers.  We had a special application at HP where we put a DC
> bias on one of the windings.  Most users do NOT do this.   These
> defective mixers caused a devil of a problem because they didn't
> just fail outright.  They would get noisy when DC was applied
> and eventually short out the DC.  It took us 6 months to get MCL
> to admit the problem.
>
> What I learned from this is that you should not wind ordinary
> enameled wire on conductive cores even if it seems to be OK
> at first.  It may be a time bomb.
>

With the "Battle Creek Special" verticals, we need to use a 2:1 UNUN for the 
160 m Inv L section.  We've been using 61 type material  and glass tape the 
cores to prevent the sort of problems described by Rick, Tom etal.

No problems so far in a tx or rx mode.

73  George  W8UVZ