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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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