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Re: [CQ-Contest] 419A Bandpass Filter - Value?

To: k9yc@arrl.net
Subject: Re: [CQ-Contest] 419A Bandpass Filter - Value?
From: Mark n2qt <n2qt.va@gmail.com>
Date: Sat, 20 Feb 2021 17:59:17 -0500
List-post: <mailto:cq-contest@contesting.com>
Competency coupled with test equipment is important of course.  I had more 
trouble
fixing the burned out 160m section of a new to me DS600.  

I agree, although I have no actual hardware to verify, I like everything about  
va6am’s
filters.  However I guess I’ll just keep using what I’ve got. 

Mark. N2QT

> On Feb 20, 2021, at 4:14 PM, Jim Brown <k9yc@audiosystemsgroup.com> wrote:
> 
>> On 2/20/2021 10:29 AM, Mark n2qt wrote:
>> Replacing the micas with Cornell Dubilier CDV style micas helps as those 
>> parts
>> have better specs for RF.  I ran rtty contests at 100 watts with no 
>> subsequent failures.
>> (My problem was always on 15)
> 
> The problem with changing or replacing parts in this filter set is that 1) 
> it's very hard to take apart to replace the parts and 2) each filter in which 
> parts are replaced must be re-aligned with good instrumentation, AND 
> measurements must made with the enclosure in place because it affects the 
> filter's tuning. So in practice, you've got to measure, tweak one or more 
> coils by squeezing or spreading them, put it back in the enclosure to measure 
> again, repeat, repeat, repeat, repeat until you get the SWR and transmission 
> loss VERY low in the passband.
> 
> The Dunestar filter sets, and the higher priced units that WX0B sells are FAR 
> superior. The high power VA6AM and 4O3A filters designed to go on power amp 
> outputs are also excellent.
> 
> 73, Jim K9YC
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