[TowerTalk] coax stubs /bandpass filter

Jim Brown jim at audiosystemsgroup.com
Mon May 24 08:58:34 PDT 2010

Hi Rag, 

What page and photo or schematic are you looking at?  Its been a few months 
since I looked through his book, but I dont recall any circuits where stubs 
were not somehow connected in parallel with the line. 


Jim K9YC

On Mon, 24 May 2010 15:57:05 +0200, Stein Roar Brobakken wrote:

>Hi Jim

>I got his book from W2JVN now, but there is two schematic I think looks like
>the shield of the stubs is just connected shield to shield and NOT further
>to a BOX f.ex. to empty can with SO-239 on top...

>Am I right what I see ??? that the shield of the coaxstubs is not mixed to
>the shield of the coax from PA ? its not look that on pictures I seen from

>This is late into the book when you have 2nd Harmonic stubs in inverted-V
>shape, and the shield is just connected into the top of where the coax meets

>73 LA6FJA Rag

>-----Opprinnelig melding-----
>Fra: towertalk-bounces at contesting.com
>[mailto:towertalk-bounces at contesting.com] P† vegne av Jim Brown
>Sendt: 29. mars 2010 09:37
>Til: towertalk at contesting.com
>Emne: Re: [TowerTalk] coax stubs /bandpass filter

>On Mon, 29 Mar 2010 08:58:24 +0200 (MEST), Stein Roar  LA6FJA-K3RAG wrote:


>>I have made a set of coaxstubs for bandpass filter, but it is not enough 
>>Is it normal with 20-30 db attunation ??

>Yes. See http://audiosystemsgroup.com/Coax-Stubs.pdf  This is a first draft
>that I'm still working on. 

>>We had big problems during WPX SSB as LN5O we experienced that the stubs
>attunate enough between 20 40 & 15m...

>You need to buy W2VJN's excellent book on this topic. You can order it for
>$20 from 
>Inrad (the filter people). Also, there are several very useful articles by
>N0AX in 
>QST. They are referenced in the tutorial (link above). 


>Jim K9YC


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