[NLRS] 6M TV2 problems - now Heliax wanted?

Tue, 7 Jan 2003 13:41:15 -0600

I'd vote for even more bandpass selectivity.    I would think that a
multi-sectional L-C filter, cavity, or helical filter, would have
significantly more band rejection than a 1/2 wave stripline.   After
attaining high selectivity, then I would try to notch any remaining in-band
strong narrow signals.

73, Jon
W0ZQ

                      "LaPlante, Bryan"                                                                                                 
                      <bryan.laplante@pra       To:       <[email protected]>                                                        
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                      qth.net                                                                                                           

                      01/07/03 12:20 PM                                                                                                 

Thanks everyone for some good suggestions on my 6M deafness problems.

I've reinstalled a strip filter (see handbook) that has given me about
another 10 dB of attenuation of the TV2 audio intermod, and no
noticeable degradation in hearing my 50Mhz weak signal source.
Progress, but not enough.

After following several links provided, I'm looking seriously at the
heliax stubs (notch filters), to notch out the Ch 2 audio and/or video
carriers.  These are built out of Andrews heliax (bigger sizes are
better).

So two questions:
As I now have a bandpass filter in place - should my next step be the
stub/notch filters?
Or should I be looking at cavity band pass filters or helical band pass
filters.

How many stubs per carrier that I'm trying to notch out?  Two?  Looks
like you get about 19 dB of attenuation per stub.  Hmmm 100KW - 19db....

Any local NLRS'ers have some heliax cut offs?  I'd need about 4 feet of
heliax per stub.  So I'd be looking for maybe 16' of heliax, ok if it is
in four 4 foot pieces.

----

Also, anyone have any ideas on how -instead of shorting the stubs - I
could use the notch filter to charge batteries, provide household power,
etc.?   ;-)

Bryan - KB0OBT