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Re: [CQ-Contest] Thoughts on automatic low-power bandpass filters

To: <w5wz@w5wz.com>, "reflector cq-contest" <cq-contest@contesting.com>
Subject: Re: [CQ-Contest] Thoughts on automatic low-power bandpass filters
From: "Dave Hachadorian" <k6ll.dave@gmail.com>
Reply-to: Dave Hachadorian <k6ll.dave@gmail.com>
Date: Wed, 21 Nov 2018 22:38:48 -0700
List-post: <mailto:cq-contest@contesting.com>
Has anyone modified and published a "how-to" to modify the ICE system for better performance?

I have a friend who has two ICE 419A's. I help him maintain his station, so I have a LOT of experience with them. As far as band-to-band isolation, the filters seem to be adequate for the job, but I'm sure others have a lot better specs.

the main problem is reliability.  there are two problems:

1. the signal path travels through 12 relay contacts, 10 of which have the relays in the normally closed (relaxed) state. This design makes the filters subject to signal dropouts on receive. The only solution that I know of for this problem is to cut the plastic tops off all 6 relays, and use Deox-it and a burnishing tool to clean all 12 of the normally-closed contacts before every contest. I tried electrically cleaning the contacts with DC voltage, but it didn't work reliably.

2. Overheating of the capacitors on 10 and 15 Meters. These are the caps that go to ground on the radio side of each band filter. The problem can be reduced by using three or four CDV16 caps in each leg. I have the spec sheet on the original design, and I am attaching it here. The reflector will probably strip it off, but at least w5wz should get it. If you have a low-drive amp, the caps are ok. If you use 100 watts , they will fail, especially on RTTY.

I wouldn't recommend buying this unit, but if you already own them, these procedures will help.

Dave Hachadorian, K6LL
Yuma, AZ
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