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Re: Topband: INV-L with traps

To: "'cris blak'" <>, <>
Subject: Re: Topband: INV-L with traps
From: "Alex" <>
Date: Sat, 26 Sep 2009 09:33:02 -0400
List-post: <">>
Hi Cristi,

What a coincidence! I just finished building 80m and 40m traps last night
myself and was going to build the "Battle Creek Special" this weekend. I
have already an inverted L (coaxial version), but supports in my small
backyard are hard to come by and always thought it was a waste to use the
one 60ft support I use for the inverted L for just one band (and the

There are a lot of myths out there about traps being very lossy (just like
with anything else in hamradio). Some of these myths are propagated by
antenna manufactures who sell antennas without traps. The loss incurred by
traps is actually not all that great. I found this article by W8JI very

That pretty much convinced me to go ahead and build the Battle Creek Special
to get the best bang for my buck (and who can't use that these days). The
loss for coaxial traps seems to be about 1.6 dB for TWO traps (he evaluates
dipoles). Of course some will cry tears over that kind of loss. 

The nice thing about the BCS antenna is that it will fit using the same
supports I have now for the coaxial inverted L, which is only 125 feet in
I have no experience to share with you, but I thought it was funny that you
were thinking and doing the same thing at the same time. :)

--Alex KR1ST

> -----Original Message-----
> From: [mailto:topband-
>] On Behalf Of cris blak
> Sent: Friday, September 25, 2009 5:09 PM
> To:
> Subject: Topband: INV-L with traps
> Hello,
> I have an INV-L for 160m which is working fine along with its 30
> radials. The vertical part is about 16m. I intend to add two traps in
> order to use it on 80m and 40m. Is there anybody who use such a design
> for DX (meaning "in practice").
> What is the difference in terms of quality between an 160m INV-L and an
> 160m INV-L with trap or traps (80/40m)?
> I already build the traps for 80 and 40m with RG58 coaxial cable and
> tune it with my miniVNA. The Q factor is around 20.
> Thanks for any advice/ report.
> 73 de YO3FFF
> Cristi
> _______________________________________________
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