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[TenTec] Re: DC blocking caps for crystal filters - question

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Subject: [TenTec] Re: DC blocking caps for crystal filters - question
From: davidc@bit-net.com (DavidC)
Date: Tue, 30 Jun 1998 22:42:17 -0400
I have just acquired a Corsair I and it has no optional filters.  My
purpose is ssb, amtor, and pactor for emergency and missionary traffic
(where the rig, antenna, and operating conditions at the other end are
generally poor, so I wish to compensate at my end).  What are your
recommendations as to filter set, mods, etc.?  (I have read somewhere that
there is a mod to the Corsair I that adds some of the filter stacking
advantages of the Corsair II.)

FYI:  I also have the matching Herc. I (444) with autobandswitching.  Any
word as to loss or added noise from the 444 in line?

Thanks & 73, DavidC  AA1FA

> Thanks to all for suggestions and answers.  It was, of course
> easy to alculate the impedance of the caps at the IF
> frequency of 6.3 MHz, and the 0.1 comes out ahead at .25 ohms,
> where the 0.01 would come out at 2.5 ohms.  Not much of a difference,
> but what the heck, I had both values lying around, so I went with
> the lower loss 0.1 alternative.  
> Notice that some filters have matching transformers at the input 
> and output (INRAD filters do this) and get a DC path through them, 
> wreaking havoc on the little switching diodes on either end.  This
> made the blocking caps necessary, and they worked fine.  The INRAD
> 8 pole CW filters work very well in my Corsair I now, and I will
> put them into my OMNI VI and probably let go of my 6 pole (ten tec) 
> Network Sciences filters now.
> Fun with filters.  Few things finer.
> Clark WA3JPG

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