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

Dave Hachadorian k6ll.dave at gmail.com
Thu Nov 22 00:38:48 EST 2018

>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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