-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Grant
Saviers
Sent: Friday, July 26, 2013 11:03 AM
To: ZR
Cc: Gary@ka1j.com; topband@contesting.com
Subject: Re: Topband: Topband Inv-L Joy
Posted on towertalk yesterday was the link to the free download of the
1952 text Radio Antenna Engineering
http://www.lulu.com/us/en/shop/edmund-laport/radio-antenna-engineering/ebook/product-17560294.html
Some fascinating stuff since much of the focus is high power
broadcasting LF/HF and point to point reliable RF links with high gain
HF wire antennas. (many pictures of amazing arrays). A quick peruse
found in a later chapter how to build high power non-inductive
terminations for rhombics etc. Make an open wire feeder of the needed Z
from iron or stainless wire and as long as the db's you wish to absorb
and with wire heavy enough to handle the current. Clever stuff,
invented when HF was a primary long distance communications technology.
The formulas are there for resistivity and ferromagnetic losses.
Of course some of the content is now pretty irrelevant since we have
cheap great coax, ferrite, and NEC software and a billion times the
worlds 1952 total computing power on every desktop.
Grant KZ1W
On 7/25/2013 8:17 AM, ZR wrote:
On a side note WD-1A conductors are a copper/cadmium alloy; whatever
that means in RF resistance. Fine for a Beverage but what is the loss?
Carl
KM1H
----- Original Message ----- From: "Gary Smith" <Gary@ka1j.com>
To: <topband@contesting.com>
Sent: Thursday, July 25, 2013 1:22 AM
Subject: Re: Topband: Topband Inv-L Joy
Had a more difficult time getting the antenna up there this time. The
first spud snapped away from the fishing line & in the dense thicket
I was unable to find where it landed. Had to make another & the
mosquitos were so thick they posted a LUAU sign on my forehead.
Till I get something better I retrieved my WD-1A military field phone
wire that was left out in the marsh as my old beverage wire. and
after a comedy of errors I finally got the antenna up.
I was earlier getting a SWR of 1.1 on 160 before and now am getting
1.1 on 1.74365 MHZ
1.74365mhz
R=51 X= 6,7,8
swr 1.1
At the desired frequency to match the antenna I've aimed for 1.8MHZ
here's the information I was able to get at my desired frequency:
1.8025 mhZ
Coax loss 6.3db
C=4193 XC=21
L=1.970 X1=21
r=41 x=21 swr 1.6
So this is what the antenna is giving me at this moment. I need to
get back down and add the broken wire to the radial bed and I should
also trim some length to bring my values to 1.1 at 1.025MHz.
Given the info above from the MFJ 259B any idea how much I might
nibble off and more, is there anything in this info that tells me I
should look to do anything differently?
Hopefully the coax loss will be mitigated by a friend bringing me
350' of hardline. Can't wait!
Thanks,
Gary
KA1J
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