AmateurRadio.com

The Mini-Whip at University of Twente's (Netherlands) Remote Receiver

A recent posting to Yahoo's ndblist Group described an interesting experiment by Dirk Claessens regarding the signal-to-noise ratio (SNR) versus height of his PAØRDT active whip. Dirk's tests were posted on Yahoo's Navtex DXing Group where some further interesting discussion seemed to confirm his findings.

Here is what Dirk discovered, backed-up with his graph data, clearly pointing to the 'ideal height' at his location ... and probably yours as well.

Hi all,

You may recall that to get rid of a source of QRM, my whip is now hanging from a rope-and-pulley system, about 5 .5 mtr from the house, at a height of 7 meter agl.
As the height of the whip can easily be changed, this is an ideal situation to test the behaviour of the whip wrt noise levels, optimal height etc..
I had done this test before some 4 years ago, but not very precise. Time to do it again, and documenting it.
What I also wanted to check, is if there were any noise sources of the own house possibly reaching the whip.
(how far does the "noise bubble" go in function of the height?)

The Perseus was tuned to 549 KHz Deutschlandfunk Nordkirchen, the station closest to 518.
2 markers were set, one to the signal, and a reference marker in a quiet spot nearby on 543 KHz, to get a reading for the noise floor.
The whip was then lowered in "1 meter each minute" steps, readings were taken and written to the marker file.

First the absolute values were plotted.
Note that: blue = noise floor, red = signal, and that the left and right axis scales have identical spans of 19dB, but are shifted, in order to get a compact graph.
We see that for a delta height of 6 meters:
-the noise floor goes up ~8dB, or 8/6 = 1.3 dB/m, almost linearly.
-the signal goes up ~14 dB, or 14/6 = 2.3 dB/m, clearly curved and showing a maximum at ~5..7 m.
The continuous lines are polynomic (2nd degree) regression lines.


The noise on the measurement values seems to increase with decreasing height.  Was this caused by my body standing under the whip, and near to the whip for the lowest measurements??

What really matters of course, is the signal over noise value, this is plotted below:


-Within a narrow 1 dB band, the curve shows a clear optimum in the region of 4..7 m agl, a familiar value often given as optimal by Roelof.
-The measurement was performed during the day and thus with ground wave propagation. As the whip is truly omnidirectional, I cannot see a reason why the behaviour would be different at low angle DX signals.
- At 5.5 meter from the house, the whip seems to be outside of the "noise bubble"

and later, following discussion:

I have just checked the noise floor again at 518 (with no signal present)

Perseus set to 125 kS/s, Span/RBW 25/30.5
Shield grounded: -125 dBm
Not grounded:  -110 dBm

That's a whopping 15 dB difference!
I have also buried the coax ~20cm deep from the grounding point to where it enters the house.

The ideal height was also that recommended by Roelof, PAØRDT, originally and points out that one of antenna-building's most sacred commandments ... "the higher the better", is not always true!

I have often recommended this simple antenna for those looking for a very effective yet low-footprint receiving antenna for use on the LF and MF bands.

Much more information about Roelof's popular miniwhip may be found in previous blog discussions here.


Steve McDonald, VE7SL, is a regular contributor to AmateurRadio.com and writes from British Columbia, Canada. Contact him at [email protected].

Hello, CD listeners! Sorry, channeling Tom Petty there for a moment. The latest episode of LHS is coming your way. In it, we talk about Java-based contest loggers, our Field Day experiences, lemon chicken, licensing, game emulators, Winlink, "cloud" Linux and more. Enjoy. And thanks for listening.

73 de The LHS Crew

Russ Woodman, K5TUX, co-hosts the Linux in the Ham Shack podcast which is available for download in both MP3 and OGG audio format. Contact him at [email protected].

This past weekend saw another of the monthly CLE listening challenges.






'CLE's' are 'Co-ordinated Listening Events', and NDB DXers around the world focus their listening time on one small slice of the NDB spectrum.

If you are interested in building a 630m system, doing some listening on the high end of the NDB band is a great way to evaluate your station's receiving performance.

The frequency range covered for CLE 208 was 400-419.9 KHz where a fair number of North American NDBs' can be found. Beacons at this end of the band also tend to propagate better than those at the lower end near 200KHz.

This weekend, typical summertime conditions prevailed, with extremely high levels of thunderstorm / lightning QRN ... propagation itself was not too bad for the middle of summer.

As usual, I set up my Perseus SDR for hourly two-minute captures of the allocated spectrum and spent a few hours going over the files during the day. I have yet to purchase and download the latest version of Perseus software but I understand that there are several improvements over the system I am using ... which is excellent for my present needs.

Here is my weekend CLE log:

02 10:00 400.0 QQ Comox, BC, CAN
02 06:30 400.0 FN Fort Collins, CO, USA
02 10:00 400.0 CKN Crookston, MN, USA
02 10:00 400.0 1L Fort MacKay, AB, CAN
02 08:30 401.0 YPO Peawanuck, ON, CAN
02 08:30 402.0 M3 Kindersley, SK, CAN
02 08:30 402.0 L4 Nipawin, SK, CAN
02 11:00 403.0 AZC Colorado City, AZ, USA
02 08:00 404.0 MOG Montegue, CA, USA
02 09:30 404.0 GCR Cordova, ALS
04 09:00 404.0 FNB Falls City, NE, USA
02 08:00 405.0 9G Sundre, AB, CAN
02 08:00 405.0 2K Camrose, AB, CAN
02 08:30 406.0 YLJ Meadow Lake, SK, CAN
02 10:30 407.0 ZHU St Hubert (Montreal), QC, CAN
03 10:30 407.0 CHD Chandler, AZ, USA
02 10:30 408.0 JDM Colby, KS, USA
02 08:30 408.0 Z7 Claresholm, AB, CAN
02 08:30 408.0 MW Moses Lake, WA, USA
02 08:30 410.0 GDV Glendive, MT, USA
02 10:30 411.0 ILI Iliamna Apt, ALS
02 09:00 413.0 YHD Dryden, ON, CAN
02 04:00 414.0 YZK Harper Ranch, BC, CAN
02 10:00 414.0 LYI Libby, MT, USA
02 10:30 414.0 IME Sitka, ALS
02 09:00 415.0 LO West Yellowstone, MT, USA
03 09:30 415.0 CBC Cayman Brac, CYM
04 08:30 419.0 RYS Detroit, MI, USA

Final details can be found at the NDB List Website and worldwide results, for every participant, will be posted there a few days after the event. If you are a member of the NDB list Group, results will also be e-mailed and posted there.

The very active Yahoo NDB list Group a great place to learn more about the 'Art of NDB DXing' or to meet other listeners in your region. There is a lot of good information available there and new members are always very welcome.
Steve McDonald, VE7SL, is a regular contributor to AmateurRadio.com and writes from British Columbia, Canada. Contact him at [email protected].

Stories you’ll find in our July, 2016 issue:

Touring the WJZ Transmitter Site in Bound Brook, New Jersey—1925
By John F. Schneider W9FGH

This month, John takes us on a tour of WJZ, NBC’s Blue Network station in New York, which debuted on October 1, 1921. Founded by Westinghouse Electric, the station was originally located in a shack, accessible only by ladder, on the roof of a Westinghouse factory located at Orange and Plane Streets in Newark, New Jersey. This was Westinghouse’s radio station – preceded by KDKA in Pittsburgh and WBZ in Springfield, Massachusetts. The 500-watt WJZ transmitter was an exact duplicate of the one built for KDKA.

TSM Reviews: Yaesu FTM-3200DR Digital/Analog 2m Transceiver
By Cory GB Sickles WA3UVV

In mid-March, Yaesu surprised just about everyone with the announcement of a new transceiver, capable of analog FM and System Fusion operation. The FTM-320 (DR/DE) is a 2-meters only, 65-watt radio, with front-facing speaker and a simple black-on-amber, dimmable display. Its small dimensions mean it can fit just about anywhere. With a current street price of $180, he believes many hams are destined to be looking for just such a spot.

How to Become an EMI Detective
By Mark Haverstock W8MSH

In a world full of electronic technology, it’s inevitable that there will be an increase in electromagnetic interference (EMI), especially on HF bands. Computers and their peripherals are the biggest offenders, causing a host of problems for those of us in the radio hobbies. Not far behind are the infamous AC power supplies known wall-warts and power bricks. And don’t forget the plasma televisions! Mark shows how to diagnose your EMI problems and how to fix them.

Tube Tester Basics: Understanding and Restoring Emission Testers
By Rich Post KB8TAD

It’s useful to have at least one tube tester around for basic checking, especially for tubes for which you have no spares or as a relative measure of quality. But, all tube testers make compromises in testing. The most basic tester and the one most commonly seen is for emission which measures the cathode current relative to its target average. The typical emission tester also includes a test for shorts and leakage between the elements of a vacuum tube. Leakage and shorts are always tested first since an emissions circuit and meter can be damaged by a shorted tube.

Free-To-Air Satellite Update Mid-Year 2016
By Mike Kohl

Change is a constant in the field of Free-to-Air (FTA) satellite-TV. While some channels continue as they have for nearly two decades, others, particularly the last of the DigicipherII subscription channels may be on life-support. FTA satellite-TV expert, Mike Kohl, reviews all of the C and Ku-band satellites viewable to North American locations and explains what you might expect to find on those channels.

Scanning America
By Dan Veenaman
APCO P-25 Explained; Scanning Creek County, Oklahoma

Federal Wavelengths
By Chris Parris
DMR Scanning Finally Here!

Utility Planet
By Hugh Stegman NV6H
HF Fax: Radio with Pictures

Digital HF: Intercept and Analyze
By Mike Chace-Ortiz AB1TZ/G6DHU
Update on NATO STANAG4285 2400 baud HF Modem Activity

HF Utility Logs
By Mike Chace-Ortiz and Hugh Stegman

Digitally Speaking
By Cory Sickles WA3UVV
Digital Dayton

VHF and Above
By Joe Lynch N6CL
ARRL June VHF Contest

Amateur Radio Insights
By Kirk Kleinschmidt NT0Z
Old Trees, Old Towers, and Living to a Ripe Old Age

Radio 101
By Ken Reitz KS4ZR
FM Mayhem Part 2: A Little Help from a 16-Element Quad-Stacked Array

Radio Propagation
By Tomas Hood NW7US
The Solar Wind

The World of Shortwave Listening
By Keith Perron
Inside the Voice of Korea

The Shortwave Listener
By Fred Waterer
Greek, Country, Gospel Music and More

Maritime Monitoring
By Ron Walsh VE3GO
Change is Inevitable

The Longwave Zone
By Kevin O’Hern Carey WB2QMY
472-479 kHz (& Vicinity) Update

Adventures in Radio Restoration
By Rich Post KB8TAD
Finishing the Hammarlund HQ-129X Part 3: Those Modifications

Antenna Connections
By Dan Farber AC0LW
Antenna 101: Let’s Review the Basics

The Spectrum Monitor is available in PDF format which can be read on any desktop, laptop, iPad®, Kindle® Fire, or other device capable of opening a PDF file. Annual subscription is $24. Individual monthly issues are available for $3 each.

Ken Reitz, KS4ZR, is publisher and managing editor of The Spectrum Monitor. Contact him at [email protected].

Here is this week’s space weather and geophysical report, issued 2016 Jul 04 0322 UTC.

Highlights of Solar and Geomagnetic Activity 27 June – 03 July 2016

Solar activity was very low. The disk was spotless for the entire period with no measurable flare activity.

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit was at high levels from 27-30 Jun and dropped to normal to moderate levels for the remainder of the period.

Geomagnetic field activity was quiet to unsettled on 27-28 Jun due to diminishing negative polarity CH HSS effects. Mostly quiet conditions were observed on 29 Jun. Quiet to unsettled conditions were observed for the remainder of the week with an isolated active period on 02/2100-2400 UTC due to effects from a series of coronal holes.

Forecast of Solar and Geomagnetic Activity 04 July – 30 July 2016

Solar activity is expected to be very low throughout the forecast period.

No proton events are expected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit is expected to reach high levels on 04-07, 16-19, and 22-26 Jul following recurrent CH HSS events.

Geomagnetic field activity is expected to be at quiet to unsettled levels early on 04 Jul followed by quiet conditions through 07 Jul. Quiet to unsettled conditions are expected to return from 08-15 Jul with active periods likely on 11-12 Jul due to effects from a series of recurrent coronal holes. Quiet conditions are expected to return from 16-18 Jul. Another recurrent CH HSS is expected to cause quiet to unsettled conditions from 19-23 Jul with isolated active periods likely on 19 Jul. Mostly quiet levels are expected for the remainder of the period with unsettled periods possible on 28 and 30 Jul due to recurrent coronal holes.

Don’t forget to visit our live space weather and radio propagation web site, at: http://SunSpotWatch.com/

Live Aurora mapping is at http://aurora.sunspotwatch.com/

If you are on Twitter, please follow these two users: + https://Twitter.com/NW7US + https://Twitter.com/hfradiospacewx

Get the space weather and radio propagation self-study course, today. Visit http://nw7us.us/swc for the latest sale and for more information!

Check out the stunning view of our Sun in action, as seen during the last five years with the Solar Dynamics Observatory (SDO): https://www.youtube.com/watch?v=zXN-MdoGM9g

We’re on Facebook: http://NW7US.us/swhfr

Visit, subscribe: NW7US Radio Communications and Propagation YouTube Channel

All about Multi-mode transceivers and the benefits of certain modes. More related questions from the amateur radio technician exam pool.

1:07:51

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YouTube

George Thomas, W5JDX, is co-host of AmateurLogic.TV, an original amateur radio video program hosted by George Thomas (W5JDX), Tommy Martin (N5ZNO), Peter Berrett (VK3PB), and Emile Diodene (KE5QKR). Contact him at [email protected].

On June 21st, I worked Steve K7PX on Mount Garfield (W0C/FR-040) using 2m fm to push me over 1000 points to quality for the SOTA Shack Sloth Award using only VHF. This is my first significant SOTA award, which I have been working towards for several years now. I decided to pursue Shack Sloth using only the VHF bands, which is much more difficult than using HF. Why? Something about mountains, Height Above Average Terrain (HAAT) and VHF radio has always intrigued me.

Here’s the line up of my top chased summits, with Mt Herman and Pikes Peak taking the clear lead. Mt Herman is The Most Radio-Active Mountain in Colorado and it is in my backyard. Most of those contacts were with Steve WGØAT and Frank KØJQZ. Thanks, guys! Pikes Peak is also a clear VHF shot from my house and many SOTA activators and tourists like to activate that summit. No surprise, the rest of the summits are various peaks in Colorado, worked from my house or from our cabin near Trout Creek Pass. Quite a few of these are Summit-to-Summit contacts made when activating peaks, often during the Colorado 14er Event.

Most of my thousand points were contacts made using plain old 2m fm, The Utility Mode. A few contacts were made on 2m ssb along with some 70 cm fm and ssb contacts. I have been encouraging folks to try 2m ssb for huge improvements in weak-signal performance but the universal nature of 2m fm seems to be winning out.

My next goal is Mountain Goat with VHF only. I’ll need to activate a lot of summits to get that done, so it will take me a while. It’s always good to have something to work towards.

73, Bob KØNR

The post All VHF Shack Sloth appeared first on The KØNR Radio Site.

Bob Witte, KØNR, is a regular contributor to AmateurRadio.com and writes from Colorado, USA. Contact him at [email protected].