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Re: [TowerTalk] ICE 419A Combination Bandpass Filter 10M Section Blown

To: TowerTalk <towertalk@contesting.com>,Tom Rauch <w8ji@contesting.com>
Subject: Re: [TowerTalk] ICE 419A Combination Bandpass Filter 10M Section Blown
From: Jeff Goldman <k3dua@erols.com>
Date: Fri, 10 Dec 2004 18:11:47 -0500
List-post: <mailto:towertalk@contesting.com>
I agree on the current problem view point on the filter failure. I had an ICE 6 meter filter that was rated at 250 watts, and it went out several times with the stock caps. I finally replaced the original caps (I think they were 50 pf each) with a parallel set of 5 10pf caps of the original type, and no more problems since. This divides the current through each, and reduces the loss (heat) which destroys caps, just like too much voltage.

73,
Jeff, K3DUA


On Dec 10, 2004, at 5:29 PM, Tom Rauch wrote:


Each filter section apparently consists of a simple coil
and two caps in T
configuration. This is only an observation as I do not
have a schematic. I
would like to beef up the capacity and assume this might
be done with higher
voltage caps.

It can also be a current problem. You really should look at component ratings and the actual current in the "tank". Just by knowing the component values you can calculate the required voltage and current ratings of the capacitors.

Remember when you reduce power, the voltage and/or current
decreases to half at 1/4th the original power.

Moving from 200W to 150W will still leave you with almost
87% of the original component stress.

You really should have more headroom than that. For example
the output filters in the ALS-600 will handle over 1500
watts for extended operating time without actually failing.
That headroom is required to make them reliable at 600
watts.

73 Tom

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