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Hi Pete , though it was too quiet ...
May be it uses spread spectrum techniques to
enhance the profit known as the
spreading gain
But ... Gary uses Mini-whips
for his grabber and I use two 20 ft
alloy scaffold poles as a 40 ft vertical , as
you can see , a good 10 db worse in s/n ,
may be its using near field technology ?
but Tx slightly HF with the vert , then
things seem to change slightly , this must
be caused by long skip on 7 ?
21:26 7038 G0NBD
de VK3KCX Op2 10587 mi -19 dB in Melbourne with 13w +
21:26 7038 G0NBD
de G4MDH Op2 139 mi -14 dB in Wootton Bassett, SW Eng with 13w
+
I
like the G2AVJ concept of near
field arrays and vector potentials
rather than E/H and Maxwell made a
slight errors using a currant twice
, funnily enough , I mentioned Prof
Cabbie CFA ( cross field Ae) [ remember the
shifnell trials , that found loading coils in the
fibreglass casting] to some one a while back ,
turned out he was in Imperial with him and
he agreed g2avj was right , but no one
talks about it as it a good way to
have your phd thesis refused and if there
are no E/H then these E/H ae will not
work , which sort of fits the CFA story ..
just because you can measure it , doesn't
mean it really there ..
Must be the its the silly season .
mf/lf closed for the summer ,
this must be magic then ? :- )
Sent: Friday, July 05, 2013 11:57 PM
Subject: Re: LF: Wellbrook RX loops
Hi Graham
Don't bring measurement and
practical Ham Radio comparisons into this you are fighting "Black Magic" and
Voodoo. Its a commercial promotion and specmanship with no real technical data
to make an evaluation. Never seen a schematic for one or an
explanation why it would be better than a "proper" antenna, an
elevated electrode tuned against ground on the frequency of interest.
73 es GL Pete M0FMT
IO91UX
There is a good example of
Mini-whip V 40 ft end fed vertical , db
levels are the average over 32 mins , so
that would tend to give a
realistic evaluation , as opposed to peak ,
which would reflect one major incident
during the time lime
Stations about 25 miles apart
west<>east
G..
23:02 136 G3XDV de G4WGT Op32 160 mi -12 dB in Chorley, IO83qo with
0.3w + Inv-L
23:02 136 G3XDV de G0NBD Op32 163 mi -23 dB in Nr Liverpool with 0.3w
+ Inv-L
Sent: Friday, July 05, 2013 5:26 PM
Subject: Re: LF: Wellbrook RX loops
Hi Roger
I use a Wellbrook Loop type ALA1530
(MW/HF) mounted 1m off the
ground and a PA0RDT mini-whip mounted about 7m above ground.
Sometimes the loop wins other times the miniwhip. The miniwhip is
omnidirectional and uses the e field, whereas the loop is directional and uses
the magnetic field. The miniwhip is more open to BC breakthough
than the loop but more sensitive. I tend to monitor with the
miniwhip, and switch to the loop after homing in on the signal if this
helps. BC breakthough is overcome using a simple series LC circuit
tuned to the required band at the RX end of the coax. The QRM at
my QRT can be horrendous, as I am only 100 yards from the OH lines on the East
Coast main railway line, surrounded by houses and a block of flats with
associated busy roads. My 'T' transmitting aerial 8m high is
useless for RX. I can fully recommend both miniwhip and
Wellbrook Loop, both of which cover from LF to 10m. For best
results, I suppose a tuned loop about 1m square has the edge, but not as
convenient.
73 Dennis M0JXM
Can anyone advise, from actual
use, how well a Wellbrook loop works on 136 and 472kHz RX ? The
excellent OIP2 and OIP3 figures and directivity suggest one could be very
useful.
73s
Roger
G3XBM
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