As a minority report by one, IMO the simplest, smallest, cheapest, good
RDF receive antenna is the DHDL. RDF around 9, pretty good for $20 of
wire, one BN-73-202, one resistor, some string and two trees (free here)
or supports 65' apart. Ground rods for a 200' BOG will cost more, take
more space, and have a poorer RDF. It's easy to make a switched
bidirectional DHDL with a couple of small relays (or DPDT switches) and
2 cores and resistors. Pretty easy to maintain and verify if it is
working. It seems pretty insensitive to nearby stuff and ground
conditions as was found using them on antenna crowded DXpeditions.
Built for 160, it also works better (more gain) on 80m. Some benefit on
40m.
Not mentioned is the challenge of troubleshooting problems in active 3,
4, & 8 element arrays, and knowing if the pattern is being developed as
modeled. Plus 100x in cost. I have a DXE active 4 square in the far
corner of my 5 acres, it works well. IMO, more verticals in an array,
the more sensitivity to phasing errors from all sources and greater the
need for isolation. There isn't much to "making them work" other than
following the manufacturers directions. If you have interactions, then
that is another set of issues re detuning or removal of the problems.
We did build a passive tuned top loaded 4 sq for 160m (see W8JI short
vertical design) for the 2017 Mellish DXpedition using a Hi-Z phasing
box and it worked well. The concern was proximity to 3 other QRO
stations and problems that would create for active antennas. See also
the 8 square passive design by W5ZN and W4HY. http://www.w5zn.org/
Of course, if I had a spare clear 2 acres, for $2K+ the 8 square Hi-Z
200 ft circle array is the way to go.
W3LPL Contest University 2017 covers all choices except the DHDL as an
example two element vertical array. Excellent.
Grant KZ1W
On 7/30/2019 12:34 AM, terry burge wrote:
Hi again folks,
Got some great advice from several others. 'Shared Apex'; KD9SV bi-directional
beverage recommended; K9AY (guess I need to get busy and finish mine); Hi-Z 8
along with Waller-Flag at 95' head and shoulders above others (but expensive
and tough to build); both K9AY and Beverages not very effected by TX ants/other
objects around them so much. No real recommendations for DHDL, EWE,
Flag/Pennant, etc. Being that my property is only one and a half acres for all
but the bi-directional KD9SV beverage it sounds like my first step is to get
the K9AY going and the beverage if I can. That does mean some 'interesting'
hill climbing exercise and hopefully my neighbor won't be target practicing
while I'm on his hillside. Don't we hams do some strange things just to be able
to hear radio signals?
Anyway, that's what I got so far. I do wonder which is better between the
'shared apex loop(s)' and maybe a 4 or 8 vertical RX array from DXE. Why hasn't
any hams wrote about what is involved in making a high impedance receive
vertical work? Of course that requires Doppler shifts I guess like I used in
the USASA for direction finding way back when (flare 7/9 style). Who would have
thought I'd be looking at using that technology so many years later?
Terry
KI7M
On July 28, 2019 at 9:27 PM terry burge <ki7m@comcast.net> wrote:
Hi folks,
I have four kits purchased on ebay for receive antennas as well as a bi-directional
beverage from KD9SV. Looking on my county plot map it looks like I can run about a 412'
beverage using my neighbors ground and mine. Got a good neighbor you could say who just
doesn't want a BOG to trip on but a beverage not too low to walk into is Ok. My ebay
provided kits are DHDL, EWE and Penant/flag/diamond from a low cost Canada source. But
I'm faced with the problem of fences, power lines, roads and my TX antennas on my 1 1/2
acre plot. If one of those antennas could handle being near the fences,etc or TX antennas
I'd like to hear about it. I've already got a K9AY in the works and that one is near my
40 meter 4-square. Running the beverage is going to be near or even under my K8UR style
80 meter 4-square made with 1/2 WL slopers. I've thought some about converting the 80
meter 4-square to using 3":irrigation tubing extended with some 3" irrigation
tubing and a coil at the elevated base b
ut
I'm just not sure if it would be an improvement. It would be near 50'
verticals if I could do it. Not sure if I would lose too much gain.
Any suggestions other than 'give up'? I've always had a time hearing the
DX especially on 160 meters.
Terry
KI7M
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