[TowerTalk] what can go wrong with a Bencher YA-1 low pass filter

[K6QD]

Hi Jim -
I've had the same problem with two YA-1's.  If you drill out the rivets you 
will find, as one would expect, a multi-pole low-pass filter comprised of 
multiple L's & C's.  The L's are straight forward and are made from heavy 
solid wire (I'm guessing #10).  The problem occurs with the C's.  The caps 
are made from two conductive end plates separated by different thicknesses 
of mylar and teflon disks as the dielectric.  The C value is determined by 
the thickness & make-up of the dielectric disks.  What happens is there is 
breakdown of the dielectric at high power levels .  When you open the filter 
you will see (the carbon flash over spots are easily visible) which caps 
arc'ed.  The ones that fail, at least in my experience, are those going to 
ground; they have the highest potential difference applied.  The capacitors 
are held together by screws, washers & nuts.  There is a slight change in 
capacitance as a function of the torque applied, but it is a small change.

Note also that the rivets (that you drill out) can be easily replaced with 
pop rivets or you can use sheet metal screws.

I have found that the YA-1 can't be beat for the money!

(See my direct mail for additional info regarding solution to your problem)






----- Original Message ----- 
From: "WW3S" <ww3s at zoominternet.net>
To: <towertalk at contesting.com>
Sent: Sunday, November 16, 2008 2:47 PM
Subject: [TowerTalk] what can go wrong with a Bencher YA-1 low pass filter


> In the middle of SS this afternoon, started to get very high swr on
> transmit, although receive signals seemed fine, after trying different
> jumpers, etc, isolated it to the Bencher low pass filter....unit is 
> riveted,
> are there any servicable parts inside? What can go wrong?
>
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