[Milsurplus] [3890_AM] TCS Filter Adaptor- Corrected Schematic

[AKLDGUY .]

> On the output side, I assume the 1K in the cathode is
> to provide some bias to the tube. Unfortunately the coil
> in the filter essentially shorts the grid to ground, so, you
> may encounter distortion with high level signals. Here I
> would suggest a 100K from the cold end of the filter to
> ground with a 0.01 across it for RF purposes.

I'm really puzzled by that recommendation.
With bias provided by the 1K cathode resistor, the grid
absolutely SHOULD be returned to ground, DC-wise.
The filter winding does that and drives V2 with signal.
It's correct as shown.

The 1K is not decoupled for RF, but there may be a reason
that I missed in an earlier post.

73 de Neil ZL1ANM


On 2/16/16, Mike Feher <n4fs at eozinc.com> wrote:
> As it is you do not have 22K anyway as the coil resistance is much lower.
> Once you isolate the filter, 22K may still be OK. As I recall the filters
> themselves like to see the 120 pf and about 1K or so of R. So, you could
> possibly try playing with getting the matching correct also on both input
> and output. The 22K needs to be in the sold end and not across the filter
> anyway. Should have mentioned that before. Keep up the good work. 73 - Mike
>
>
> Mike B. Feher, N4FS
> 89 Arnold Blvd.
> Howell, NJ, 07731
> 732-886-5960
>
>
> -----Original Message-----
> From: Milsurplus [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of
> David Stinson
> Sent: Monday, February 15, 2016 8:56 AM
> To: milsurplus at mailman.qth.net; boatanchors at mailman.qth.net
> Subject: Re: [Milsurplus] [3890_AM] TCS Filter Adaptor- Corrected Schematic
>
> To my happy surprise, several of our great "smart people" have written me
> and offered good suggestions on improving the filter adaptor.  I will give
> them a try and report back.  I especially like those that get the DC off
> the
> filter input.  Will probably need to change the 22K plate resistor.  73
> Dave
> S.
>
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