[Boatanchors] Low Pass Filter Comparisons

[EP Swynar]

Hi Glen,

The old Barker & Williamson low pass filters were supposed to be one of the
best made, too...

Indeed, some years ago there was a very detailed writeup in QST comparing
many different brands of LP filters, & B&W ranked right up there, as I
recall.

~73~ Eddy VE3CUI - VE3XZ


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----- Original Message ----- 
From: "Glen Zook" <gzook at yahoo.com>
To: <boatanchors at mailman.qth.net>; "Peter Markavage" <manualman at juno.com>
Sent: Wednesday, November 12, 2008 10:08 AM
Subject: Re: [Boatanchors] Low Pass Filter Comparisons


> One thing that has definitely helped with the TVI complaints is the
widespread use of cable television these days.
>
> My main linear is a Tempo 2001 (pair of 8874 tubes) that, unfortunately,
was poorly designed, at least in terms of physical layout.  I was traded my
2001 brand new back in the 1970s and immediately found out that it had
problems.  Things like the final tank coil is right next to the power
transformer with NO shielding between, almost no bypass capacitors, etc.
The only shielding was the cabinet cover and that did not make physical
contact to the chassis because of heavy paint.  Now the TVI problems were
before cable television, but I leave the filters in place because there are
still a couple of my neighbors that don't have cable even though it has been
available for almost 30 years!
>
> It took a lot of work but I was finally able to completely eliminate TVI
from the Tempo 2001.  But, it took 2 of the Drake filters (in series) to get
rid of the last of the TVI.  I do have one on the output of my Heath HA-10
Warrior, on my Heath Apache, Heath DX-100, and a spare, or two.  All of
those transmitters are "clean" with the Drake filters in place but do cause
slight TVI on my television sets without them.
>
> I tried the Yaesu filter on the Tempo linear and although it does help
some, it is no where near as good as a single Drake.  Now I have not
actually made any "real" measurements of the harmonic reduction.  But, the
fact that TVI has been completely eliminated with the Drake filters is a
fairly good indication that they are doing the job.
>
> Glen, K9STH
>
> Website:  http://k9sth.com
>
>
> --- On Tue, 11/11/08, Peter Markavage <manualman at juno.com> wrote:
>
> From: Peter Markavage <manualman at juno.com>
>
> Way, way back in the late 50's and 60's, I used the TV-1000-LP's on
several rigs, and I guess they worked, since I don't recall any neighbor
complaints when TV's were very susceptible to TVI. Discarded them some time
in the 70's and haven't used a low pass filter since. Still don't have any
TVI complaints.
>
>
>
> _______________________________________________