Topband: HS72B

[by way of Bill Tippett <btippett at alum.mit.edu>]

Milt spelled it out pretty completely from our standpoint. Since XZ0A, a 
low dipole is a staple item in my antenna bag.

HS72B has the additional issue of discrete local noise sources to try to 
hide from.  XZ1N had noise, but not so much discrete noise like a single 
local leak. XZ0A was so quiet that at noon that on the north beverages you 
could hear the AC powerline buzz from the shore 7 miles away across the 
Indian ocean, and little else,  The night time noise level was many S units 
higher, depending on the antenna, so the noise we are working to eliminate 
is propigated, in that situation.  I dont think we are down to the 
propigated noise level at HS72B by many many dB.

current config at HS72B in order of performance at sunset
1: full size dipole up about 4-5 M under the trees
2: Low assymetric dipole 300M away- neck & neck with
3: dipole on ground - 1/3 size
4: K9AY quad with poor ground
5: half wave clean terminated beverage, North, west side
6: halk wave clean terminated beverage North, east side
7: half wave clean terminated beverage, South, west side


Ant 1 is most often best, 2,3,4 fight it out for second depending on 
directon, time of night and the noise situation of the moment.  on 80, the 
K9AY works best most of the time, still better than the beverages- which 
are 1.2 wave bevs at 80M

the beverages rarely hear as well as the K9AY, & often the big dipole is 6 
dB S/N better than either.. that is you hear em in the dipole and dont on 
the others unless its louder signals

have tried several other beverage combinations that did not function 
usefully.  All beverages showed VSWR at 1.5 or so 1500-3000 Khz, so terms 
working even tho ground connection poor.  All beverages tried are Beverage 
On Ground, if you consider the surface of a dry cracked clay field with 
half dead grass "ground"

several items impacting beverages.  we have a common area for the tx and rx 
antennas, every beverage crosses several radials of the 160 and 80 
antennas, very bad practice, but unavoidable here.  Only had one 
substantially separated, and it did not work at all, we believe because it 
ran parallel and within 150 ft of the triple stack 240KV lines - the lines 
effectively shielded the beverages- not all that much noise, just no useful 
signal.

had a second K9AY quad up at the start, it turned out to be closer to the 
discrete noise sources & was useless

Yesterday, I pushed the envelope of our hosts tolerance and ran 300M of rg6 
across the way up to the north face of a facilities building & hung a 
lopsided dipole in the parkway trees..  about 4-5 M high, 1/4 one side 1/10 
the other side.  On average, it hears less power noise from a discrete 
source, but, unless the really bad buzz is on, does not out perform the 
original full dipole

Last night, N5IA was marginally better on this antenna than the big dipole, 
but not by much, and it was 2-3 letters each peak....  sorry couldnt drag 
anyone else out.. my ears are still ringing.

I will be on steadily from 11Z to 16Z barring trouble the next 3 nights.

I am very interested in 9V1GOs experiments.  I also wonder if high angle 
efficient transmit antennas might do well.  I guess the ideal would be a 
full half wave dipole a half wave high over water.  it should be possible 
to chose a length of radiator in a vertical that nulls the low angle 
energy, but that may require use of my balloon lifter to get to 3/4 wave 
element length

I also have to note for comparison that the tx "ERP" from HS72B is at least 
6 dB below "full performance" - 4 dB in power and at least 2 dB in ground 
system, and 1 or 2 in tree absorbtion... once I saw how the TX/RX signal 
ratios were, I stopped working on making the TX louder.  I estimate that 
XZ0A was within about 1dB..  We could have put out more lower resistance 
radials, or better, elevated them to flat and tuned them, but it hardly 
seemed necessary for such a trivial signal increase at XZ0A, and here, it 
would be adding insult to injury to be louder.

Ill be following this thread with considerable interest.... more trips to 
Asia are on my to do list.

(Where is there a 160 specific most wanted list?  especially by continent?)

no more on this from me until I get home, getting buried in projects to 
clean up.  Milt and Bill have explained this quite well, I think

robin, wa6cdr at hs72b