Hi Gang,
I also had fun in the ARRL Test this weekend. Worked 30 DX stations in a
few casual hours of operation. Only got 2 all time new ones though.
But to the item at hand. Last year I built the Paul Carr N4PC Bi-Delta from
CQ magazine. This antenna is a delta loop, apex down, ladder line fed, with
a 20M 1/4wave shorting stub in the middle of the top horizontal wire. Its
OAL is 142 feet not including the stub. It operates as a full wave loop on
40, a bi square on 20, and a dipole on 30. Mine was in the air for only a
week over the summer at my cottage. It performed well on 40 and 20 but 30
was awful. I had to replace it because the feed point was only 6' over the
badmitton (sp?) net. It upset the natives.
I would try one at home but I see that RadioWorks has a similar antenna in
their catalog. I would homebrew this in a jiffy if I knew the answers to
the following question.
1. The OAL is 120.5', a bit short for a full wave 40M loop. Does the 16'
shorting stub ADD to this length? If so, then the OAL is 120.5 + 2 x 16' =
152.5'. This is a bit long but should tune up fine.
2. On 20M, assuming the shorting stub works, the bi-delta legs are 60'
long. This is much too short. I think each leg should be about 72'. Am I
missing something here?
3. What does the shorting stub do on 30M, ? The top leg is 56'. If the
shorting stub has no effect then the antenna operates like a longinsh
dipole?
4. What IS the Dedicated Matching Unit at the feedpoint of the SuperLoop40?
Would it not be best to feed this antenna with ladder line?
I would simply add some wire and the shorting stub to my 30M delta loop
today if I thought that this HB superloop would "fly". What do you think?
Does anyone out there own one of these? If I put got one of these to work
well I could convert my XBeam to 15M and be a really happy camper!
72, Mark N2VPK
Member of the Buffalo QRP Connection
[
QRP-L Archive |
]
[
1993 |
1994 |
1995 |
1996 |
1997 |
1998 |
1999 |
2000
]