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Re: [IRCA] PHOOLS IN THE PHIELD



(sorry again for delays in replying)

Hi Mark,

Re the different sizes of DKaz, and Kaz' comment on heights: With the 200 footer, would anything be gained from pushing the aspect ratio closer to that of the smaller DKaz? (i.e. higher supports). Not sure about the practical details of doing that within the time allotted, but at least you have the space; it would likely involve a third DKaz, so maybe not this time! I know, I should run the models, but things have been more out of control over the last few days than usual.
Desert ground....if you're using the same 
location year after year, maybe install a 
permanent ground system (long rods?) that you are 
happy with.   From the ground conductivity maps 
for the desert, it looks as if you "just" need to 
add water and stir (drive a tanker truck from 
Grand Junction?).   (experience with permanent 
grounds at Grayland range from one of 
us  puncturing a water line (and the motel owner 
STILL welcomes us)  to using quantities of cat 
litter to attempt to improve the conduction from 
rod to water table.   The latter didn't seem to 
work too well either, and the dunes and the dune 
grass soon swallowed it up; so much for permanence)
All transformers and chokes are placed in Hammond boxes; some shielded.
Careful where you put the unshielded ones.    I 
recently threw a nice 1:1 toroidal isolation 
transformer in a plastic Hammond box with BNCs on 
either side.   Picked up noise wonderfully from a 
"too nearby" laptop.   A couple of meters away, it was OK.
I always enjoy your graphics.   "How are the 
bands, Bones?"  "They're dead Jim"    Yes, I've had those days.

best wishes,

Nick




At 16:05 24-03-16, Mark Durenberger wrote:
Hereâ??s the not-awaited pre-report of our thinking about a 2016 Utah desert DXPedition.
<http://www.durenberger.com/documents/PRESBT2016.pdf>http://www.durenberger.com/documents/PRESBT2016.pdf

Sass back as appropriate.


Cheers!

Mark Durenberger
There's SO much I don't want to know!

From: <mailto:neilkaz58@xxxxxxxxx>Neil Kazaross
Sent: Monday, March 14, 2016 12:21 PM
To: <mailto:markwa1ion@xxxxxxx>Mark Connelly
Cc: <mailto:contiba@xxxxxxxxx>contiba@xxxxxxxxx ; <mailto:nhp@xxxxxxxx>nhp@xxxxxxxx ; <mailto:bportzer@xxxxxxxxxxx>Bruce Portzer ; <mailto:charlesh3@xxxxxxx>Charles Hutton ; <mailto:bw@xxxxxxx>Bill Whitacre ; <mailto:dx@xxxxxxxxxxxxx>Guy Atkins ; <mailto:Mark4@xxxxxxxxxxxxxxx>Mark Durenberger ; <mailto:mauno.ritola@xxxxxxxxx>Mauno Ritola ; <mailto:ibbmon.kre@xxxxxxxxx>ibbmon.kre@xxxxxxxxx ; <mailto:victor.goonetilleke@xxxxxxxxx>Victor Goonetilleke
Subject: Re: Bowtie twisted loop

Embedded comments prefaced by (KAZ)

I agree with Neil's observation about need to vary termination resistance remotely based on the Bowtie experiments I did here in 2010.
Drawing:
<http://www.qsl.net/wa1ion/pictures1/bowtie_s_yarmouth.gif>http://www.qsl.net/wa1ion/pictures1/bowtie_s_yarmouth.gif

That one had about a 4:1 horizontal / vertical aspect ratio.

I used in-shack termination rather than Vactrol since I wanted to pattern-switch and possibly even phase the east side feedline against the west side for "surgical" single-pest removal during live DX.
(KAZ) Phasing one end against the other 
basically maintains the pattern but generates a 
deeper null than is possible with Rt alone. 
However, said null is very narrowband. If I had 
a small yard and did have the SDR need for 
wideband F/B I'd certainly phase one end vs the 
other as I believe it is the best use of the antenna for a single freq.
Based on this discussion I don't think feedline 
pick-up had much of a role in making the 
termination resistance for best lowband results 
(NY 570, 660, etc.) different from that needed 
to take down highband pests (NY 1190, 1280, 
1560).  It seems that this is inherent to the 
antenna and isn't likely to be improved by going 
Vactrol, at least with my relatively short (100 
ft. / 30m) speaker wire feedlines.
(KAZ) I'm not convinced that we're sure that a 
Vactrol won't provide at least slightly better 
or more broadbanded F/B with a fixed setting. ie 
ideal for Perseus to record the entire band. 
Mark if it isn't too much trouble, I recommend 
setting up initially with a Vactrol so you can 
establish a baseline for how deep nulls can be 
and also whether the null can be acceptable at 
from 570 to 1560 with a single setting of Rt. 
Then you'll know with certainly if things 
degrade with you switch to the dual feed line and pot method.
As I think Bruce's small lot would also result 
in short feedline lengths, I think that the way 
to go would be dual feedlines and in-shack pot 
termination, the same as what I do here on the 
TA SuperLoop and eventually also on the Bowtie that will replace it.
(KAZ) Then Bruce could phase one end vs the 
other as desired for enhancement of F/B vs specific pests.
I also think that if the feedpoints need to be 
more than about 8 ft. above ground, you might as 
well just have them halfway up the sides and be 
done with it.  With any luck you won't have to 
drop the antenna for maintenance that often once 
everything is operational.  Obviously you want 
your transformer boxes and all connections thereto robust / weather-hardy.
(KAZ) I agree as my modeling shows that Bruce's 
antenna should perform significantly better with center feed and terminated.
The Bowtie I'll be putting up soon, in roughly 
the same location as the 2010 one, should be 
about 3:1 aspect, 90 ft. / 27m horizontal to 30 
ft. / 9m vertical.  The plan is for the bottom 
corners of the antenna to be about 5-6 ft. above 
ground and the tops 35-36 ft. with UV-resistant 
dacron ropes over the tops of the black locust trees up around 50 ft.
Feedpoints in the center of each vertical side 
with 9:1 transformers initially installed to 
supply speaker-wire feedlines to the in-shack 
500 ohm termination pot switch-swappable with 
2:1 transformer to W7IUV amp to receiver (or 
phaser, with south SuperLoop being 'input B').
(KAZ) My modeling and live experience phasing a 
west loop vs a south one for example, do show 
that while you can null a specific pest, the 
resultant pattern isn't very good. Of course 
this can luck out along the coast when the DX is 
from one wide beam direction but is unacceptable 
here in the Midwest where I need a more narrow 
beamwidth and a clean pattern. Better to phase 
one end vs the other if you need to crush a NYC pest down 40-50 dB for example.
Fortunately the area between the trees is 
primarily open grass and vegetable garden plots 
about 20 ft. ahead of the barn / workshop.
At some point I could think of going over to a 
Vactrol scheme with DC passed out on the east 
feedline and choke-coupled through the antenna 
elements to get to the Vactrol box halfway up 
the west side.  This will be an offshoot of 
what's shown in my 2000 Pennant article:
<http://www.qsl.net/wa1ion/doc1/pennant.pdf>http://www.qsl.net/wa1ion/doc1/pennant.pdf

That method gets rid of any need for a separate control line heading to the termination end (west, more or less, in my case). You do, of course, give up the switchable pattern reversal so this method would only come into play if there was a clear advantage in null-depth / broadbandedness versus the dual feedline approach.
(KAZ) This is convenient but I presume can't be 
used with amplification at the feed point like 
Bill and I and some others here do with the FLG100LN.
At this time Chuck Hutton, Bill Whitacre, Colin 
Newell, and a few others have been hashing over 
different variations on Vactrol control 
circuits.  Smoothness of operation in the 
typical 400-1600 ohm termination range, along 
with circuit simplicity and low cost, are key 
topics.  It will be interesting to see what comes out of that.
There is a lot of good circuit modelling, d-i-y, 
and real-world DXpeditioning research going on 
with people on this distribution as well as guys 
like Lankford and hams on the Topband list.  Not 
even to mention Gary DeBock's unique world of portable receiver enhancements.
An interesting time in a hobby that isn't ready 
to roll over and play dead yet.
(KAZ) Believe me, this hobby isn't dead yet!


On Sat, Mar 12, 2016 at 10:46 PM, Mark Connelly <<mailto:markwa1ion@xxxxxxx>markwa1ion@xxxxxxx> wrote: I agree with Neil's observation about need to vary termination resistance remotely based on the Bowtie experiments I did here in 2010.
Drawing:
<http://www.qsl.net/wa1ion/pictures1/bowtie_s_yarmouth.gif>http://www.qsl.net/wa1ion/pictures1/bowtie_s_yarmouth.gif

That one had about a 4:1 horizontal / vertical aspect ratio.

I used in-shack termination rather than Vactrol since I wanted to pattern-switch and possibly even phase the east side feedline against the west side for "surgical" single-pest removal during live DX.
Based on this discussion I don't think feedline 
pick-up had much of a role in making the 
termination resistance for best lowband results 
(NY 570, 660, etc.) different from that needed 
to take down highband pests (NY 1190, 1280, 
1560).  It seems that this is inherent to the 
antenna and isn't likely to be improved by going 
Vactrol, at least with my relatively short (100 
ft. / 30m) speaker wire feedlines.
As I think Bruce's small lot would also result 
in short feedline lengths, I think that the way 
to go would be dual feedlines and in-shack pot 
termination, the same as what I do here on the 
TA SuperLoop and eventually also on the Bowtie that will replace it.
I also think that if the feedpoints need to be 
more than about 8 ft. above ground, you might as 
well just have them halfway up the sides and be 
done with it.  With any luck you won't have to 
drop the antenna for maintenance that often once 
everything is operational.  Obviously you want 
your transformer boxes and all connections thereto robust / weather-hardy.
The Bowtie I'll be putting up soon, in roughly 
the same location as the 2010 one, should be 
about 3:1 aspect, 90 ft. / 27m horizontal to 30 
ft. / 9m vertical.  The plan is for the bottom 
corners of the antenna to be about 5-6 ft. above 
ground and the tops 35-36 ft. with UV-resistant 
dacron ropes over the tops of the black locust trees up around 50 ft.
Feedpoints in the center of each vertical side 
with 9:1 transformers initially installed to 
supply speaker-wire feedlines to the in-shack 
500 ohm termination pot switch-swappable with 
2:1 transformer to W7IUV amp to receiver (or 
phaser, with south SuperLoop being 'input B').
Fortunately the area between the trees is 
primarily open grass and vegetable garden plots 
about 20 ft. ahead of the barn / workshop.
At some point I could think of going over to a 
Vactrol scheme with DC passed out on the east 
feedline and choke-coupled through the antenna 
elements to get to the Vactrol box halfway up 
the west side.  This will be an offshoot of 
what's shown in my 2000 Pennant article:
<http://www.qsl.net/wa1ion/doc1/pennant.pdf>http://www.qsl.net/wa1ion/doc1/pennant.pdf

That method gets rid of any need for a separate control line heading to the termination end (west, more or less, in my case). You do, of course, give up the switchable pattern reversal so this method would only come into play if there was a clear advantage in null-depth / broadbandedness versus the dual feedline approach.
At this time Chuck Hutton, Bill Whitacre, Colin 
Newell, and a few others have been hashing over 
different variations on Vactrol control 
circuits.  Smoothness of operation in the 
typical 400-1600 ohm termination range, along 
with circuit simplicity and low cost, are key 
topics.  It will be interesting to see what comes out of that.
There is a lot of good circuit modelling, d-i-y, 
and real-world DXpeditioning research going on 
with people on this distribution as well as guys 
like Lankford and hams on the Topband list.  Not 
even to mention Gary DeBock's unique world of portable receiver enhancements.
An interesting time in a hobby that isn't ready 
to roll over and play dead yet.
Mark Connelly, WA1ION
South Yarmouth, MA

-----Original Message-----
From: Neil Kazaross <<mailto:neilkaz58@xxxxxxxxx>neilkaz58@xxxxxxxxx>
To: Bruce Conti <<mailto:contiba@xxxxxxxxx>contiba@xxxxxxxxx>
Cc: Nick Hall-Patch <<mailto:nhp@xxxxxxxx>nhp@xxxxxxxx>; Mark Connelly <<mailto:markwa1ion@xxxxxxx>markwa1ion@xxxxxxx>; Bruce Portzer <<mailto:bportzer@xxxxxxxxxxx>bportzer@xxxxxxxxxxx>; Charles Hutton <<mailto:charlesh3@xxxxxxx>charlesh3@xxxxxxx>; Bill Whitacre <<mailto:bw@xxxxxxx>bw@xxxxxxx>; Guy Atkins <<mailto:dx@xxxxxxxxxxxxx>dx@xxxxxxxxxxxxx>; Mark Durenberger <<mailto:Mark4@xxxxxxxxxxxxxxx>Mark4@xxxxxxxxxxxxxxx>; Mauno Ritola <<mailto:mauno.ritola@xxxxxxxxx>mauno.ritola@xxxxxxxxx>; Vlad Titarev <<mailto:ibbmon.kre@xxxxxxxxx>ibbmon.kre@xxxxxxxxx>; Victor Goonetilleke <<mailto:victor.goonetilleke@xxxxxxxxx>victor.goonetilleke@xxxxxxxxx>
Sent: Sat, Mar 12, 2016 6:24 pm
Subject: Re: Bowtie twisted loop

Hopefully TA cx improve and you can do a good test. But for now, how much, if at all, do you think back end QRM has been reduced? Are you getting stations from Maine better than before?
I do think you'll want some way to vary Rt from 
the shack. This is probably more important for 
your compromise antenna than for ones with full dimensions.
73 KAZ

On Sat, Mar 12, 2016 at 1:44 PM, Bruce Conti <<mailto:contiba@xxxxxxxxx>contiba@xxxxxxxxx> wrote: On Sat, Mar 12, 2016 at 6:47 PM, Neil Kazaross <<mailto:neilkaz58@xxxxxxxxx>neilkaz58@xxxxxxxxx> wrote: My modeling shows that you'd clearly improve things if you could feed and terminate this at the centers of the ends. However, I found a decent compromise for you and that is to feed and terminate it 22% of the way up... In that case the end radials do help... The issues here are that the aspect ratio is too low for best patterns. But if you go to something like a 3:1 aspect ratio then you have 20 ft x 60 ft and that won't provide much low end signal. If only you had a couple of usable trees 90 or 100 ft apart!

Thanks for taking a look. I wish I had 100-ft or more room for antennas. My lot is only 100 x 100-ft, and I have to use the trees toward a back corner of the lot, otherwise the antenna would be too close to power lines and houses, in addition to becoming too visible. The termination and matching transformer are actually about 5% or 2-ft of the way up if that makes any difference. Can't reach any higher with the ladder, and lowering the height of the antenna would make it too conspicuous. Being in a city lot and antenna restrictive private neighborhood requires many compromises in antenna design.
--
Bruce Conti
B.A.Conti Photography <http://www.baconti.com>www.baconti.com
¡BAMLog! <http://www.bamlog.com>www.bamlog.com




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