jeremy-ge wrote:
> Id lean to the B&W, it gives you almost 500 Ohms Xl at 160 which is OK.
> Bypass the filament transformer end with .05 to .1 uF discaps. Ive no
> idea what the MFJ's intended use is.
>
"Back in the old day", I wound a number of them on ferrite rods. I only
remember the approximation of size but it seems as if the specs were in
one of the handbooks. The rod was between 1/2 and 5/8" in diameter and
about 6" long. The winding was close spaced, bifilar wound using #10
enameled wire. One would handle a pair of 3-500's or 8877. I had a bunch
of them but they and a lot of other stuff went when I did the first
thorough clean out of "stuff I'll probably never use". I wish I had all
that *stuff* back.
At any rate, the chokes were easy to wind, worked well, cost little,
and looked good. I say they worked well. They was 80 through 10. I
never tried one on 160 and I don't remember the impedance.
> The homebrew will work also but you will have to keep an eye on the
> voltage drop.
>
I used one of the above on a pair of 813's with the voltage remaining
well with in spec. Too bad it was so long ago that I don't remember any
specifics.
73
Roger (K8RI)
> Carl
> KM1H
>
> ----- Original Message -----
> From: "Steve Flood" <kk7uv@bresnan.net>
> To: <rfamplifiers@yahoogroups.com>; <amps@contesting.com>
> Sent: Sunday, December 21, 2008 8:19 AM
> Subject: [rfamplifiers] which cathode choke?
>
>
> I have three different bifilar wound ferrite rod chokes.
>
> A homebrew choke measuring 127uH
> A B&W FC-25A measuring 44uH.
> An Ameritron/MFJ #10-15115-1 measuring 19uH.
> The measurements were taken on one winding with an Elenco LCR meter.
>
> Which one would best for grounded-grid 813's operating 160m thru 20m?
>
> Thanks, Steve KK7UV
>
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>
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