AmateurRadio.com

Mark, VA7MM, had come up with a nicely-designed antenna that will serve as his main 630m radiator. Not only that but it can be used on 10m, 15m and 30m and 160m as well!


The antenna consists of a mini-flat top dipole, with three resonant dipole legs all terminating at a common feedpoint.


This can be used directly on any of the three high bands. Shorting the end of the coaxial cable, dropping vertically down from the feeedpoint, the dipole feedline becomes the vertical element of a top-loaded 630m 'T' antenna, 100' in the air.


With suitable loading coils and appropriate switching, the 'T' will also be used on 160m, making the versatile antenna work on five different bands ... a nice demonstration of basic antenna principles put into real practice!
Steve McDonald, VE7SL, is a regular contributor to AmateurRadio.com and writes from British Columbia, Canada. Contact him at [email protected].

By John ‘Miklor’ K3NXU

PERFORMANCE  TESTS  –  LMR-450G
The recently announced LMR-450G cable has aroused much curiosity since its characteristics have not been collectively available by any one source.  By multiple inquiries to several manufactures (only three at this time) and numerous lab tests, we hope to put many of the existing questions to rest.

DESCRIPTION
The physical make up of this cable varies slightly from most conventional RF cables.  The center conductor is a semi-stranded copper alloy surrounded by Telfon, which will absorb and distribute cable ‘hot spots’ caused by excessive standing wave.  The double silver braid and foil outer coating which provides a 98.6% shield is what the inverted high frequency loss characteristics are attributed.  The loss is substantially less as the frequency increases, making this cable especially attractive for UHF, cellular, PCS and microwave applications.

LOSS PER 100′
30 MHz     2.4 db
50 MHz     2.1 db
150 MHz    1.6 db
450 MHz    1.1 db
800 MHz    .51 db
1200 MHz  .37 db
1950 MHz  .31 db

The cable’s most unique property is attributed to the outer jacket material Neo-glow, an RF sensitive composite plastic which will visibly indicate RF ‘hot spots’ in the cable.  Adjusting the cable length to the antenna system for the ‘perfect’ impedance match is crucial at high frequency, thus the importance of a low SWR for peak performance.

PROPER  INSTALLATION
The low level emission of light from LMR-450G cable can be enhanced by wearing lightly tinted sunglasses with UV protection, which enhances the light radiation from the cable.  Select an approximate length of cable needed for the installation which must be multiples of a 1/4 wavelength for the desired frequency.  The exact length can be determined by using the formula 467 / Freq (MHz) plus approximately 18 inches.

The initial tests should be run with a 50 ohm dummy load at one end of the cable.  With a minimum of 7 watts from the transmitter, you will see a faint glow from the cable indicating the ‘hot spots’ to be eliminated.  These are the points along the cable where the RF is at its maximum.  It is at these points where the RF connectors should be mounted.  Trimming the excess cable may be required at both ends of the cable to produce the most effective match.  Use caution not to trim too much cable as the loss characteristics improve with longer cable lengths.

SUMMARY
This could be the beginning of the long awaited high frequency “SUPER” cables.  Only available in limited quantities at this time; contact your local cable supplier for more details.

Hans, PD0AC, is a regular contributor to AmateurRadio.com and writes from Almere, The Netherlands. Contact him at [email protected].

By John ‘Miklor’ K3NXU

PERFORMANCE  TESTS  –  LMR-450G
The recently announced LMR-450G cable has aroused much curiosity since its characteristics have not been collectively available by any one source.  By multiple inquiries to several manufactures (only three at this time) and numerous lab tests, we hope to put many of the existing questions to rest.

DESCRIPTION
The physical make up of this cable varies slightly from most conventional RF cables.  The center conductor is a semi-stranded copper alloy surrounded by Telfon, which will absorb and distribute cable ‘hot spots’ caused by excessive standing wave.  The double silver braid and foil outer coating which provides a 98.6% shield is what the inverted high frequency loss characteristics are attributed.  The loss is substantially less as the frequency increases, making this cable especially attractive for UHF, cellular, PCS and microwave applications.

LOSS PER 100′
30 MHz     2.4 db
50 MHz     2.1 db
150 MHz    1.6 db
450 MHz    1.1 db
800 MHz    .51 db
1200 MHz  .37 db
1950 MHz  .31 db

The cable’s most unique property is attributed to the outer jacket material Neo-glow, an RF sensitive composite plastic which will visibly indicate RF ‘hot spots’ in the cable.  Adjusting the cable length to the antenna system for the ‘perfect’ impedance match is crucial at high frequency, thus the importance of a low SWR for peak performance.

PROPER  INSTALLATION
The low level emission of light from LMR-450G cable can be enhanced by wearing lightly tinted sunglasses with UV protection, which enhances the light radiation from the cable.  Select an approximate length of cable needed for the installation which must be multiples of a 1/4 wavelength for the desired frequency.  The exact length can be determined by using the formula 467 / Freq (MHz) plus approximately 18 inches.

The initial tests should be run with a 50 ohm dummy load at one end of the cable.  With a minimum of 7 watts from the transmitter, you will see a faint glow from the cable indicating the ‘hot spots’ to be eliminated.  These are the points along the cable where the RF is at its maximum.  It is at these points where the RF connectors should be mounted.  Trimming the excess cable may be required at both ends of the cable to produce the most effective match.  Use caution not to trim too much cable as the loss characteristics improve with longer cable lengths.

SUMMARY
This could be the beginning of the long awaited high frequency “SUPER” cables.  Only available in limited quantities at this time; contact your local cable supplier for more details.

Hans, PD0AC, is a regular contributor to AmateurRadio.com and writes from Almere, The Netherlands. Contact him at [email protected].

Heathkit announced today they have reached an agreement to acquire the assets of Radio Shack for $300M, blocking efforts from mobile wireless carrier Sprint to acquire a large portion of the struggling and now bankrupt North American consumer electronics retailer.  No further details were mentioned by Heathkit other than they “had big plans” and “everyone should stay tuned to the website for details.”

Radio Shack CEO Joseph Magnacca was quoted in a press release as saying “We are very happy and excited about the pending transaction with Heathkit.  The Heathkit team has shown us they have a more viable business plan than Sprint, and our creditors agree that the Heathkit team brings a higher level of management, leadership, and strategy to Radio Shack, more than the company has ever had.”

Immediately after the announcement amateur radio online forums were alive with discussions and speculation on when closed stores would reopen.  Several commenters reminisced about the days when Radio Shack offered amateur radios and components.  One person noted how difficult it is to get good 68k ohm resistors and Radio Shack could chart a course to profitability if they just stocked these resistors.  Others bemoaned Radio Shack’s practice of asking for customer addresses, claiming it was a front for NSA information-gathering efforts.  Several commenters agreed that Radio Shack should offer a vacuum tube code practice oscillator kit.

Anthony, K3NG, is a regular contributor to AmateurRadio.com.

Here is the current forecast discussion on space weather and geophysical activity, issued 2015 Mar 31 1230 UTC.

Solar Activity

24 hr Summary: Solar activity was at low levels with C-flare activity from both Regions 2303 (N18, L=065) and 2305 (S10W58, Dho/beta). The largest flare of the period was a C4 at 30/2205 from Region 2303 just beyond the NW limb. Slight decay was observed in the leading spots of Region 2315 (S20W36, Dro/beta) and the trailing spots in Region 2305. No Earth-directed coronal mass ejections were observed.

Forecast: Solar activity is likely to be at low levels with a slight chance for an isolated M-class (R1-R2, Minor-Moderate) flare for day one (31 Mar). An increased chance for M-class activity is expected by days two and three (01-02 Apr) as old Regions 2302 (N12, L=189) and 2297 (S17, L=196) are expected to return.

Energetic Particle

24 hr Summary: The greater than 2 MeV electron flux at geosynchronous orbit was at normal levels. The greater than 10 MeV proton flux at geosynchronous orbit remained at background levels.

Forecast: The greater than 2 MeV electron flux at geosynchronous orbit is forecast to be at normal to moderate levels all three days (31 Mar -02 Apr) The greater than 10 MeV proton flux at geosynchronous orbit is expected to be at or near background conditions (Below S1-Minor) for the forecast period.

Solar Wind

24 hr Summary: Solar wind speed at the ACE spacecraft for the majority of the period was in the mid-300 km/s range but increased to near 400 km/s after 0730 UTC. Phi was negative. Bz was at or above -4 nT and Bt was less than 7 nT through 0730 UTC when it increased to near 16 nT. The increase in activity is likely due to the onset of a coronal hole high speed stream (CH HSS).

Forecast: Continued enhancement of solar wind parameters is anticipated on day one (31 Mar) and remain enhanced through day three (02 Apr) as the CH HSS becomes geoeffective.

Geospace

24 hr Summary: The geomagnetic field was at quiet levels.

Forecast: Unsettled to active conditions are expected to dominate through day three (02 Apr) due to CH HSS effects. trans-equatorial high speed stream becomes geoeffective.

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Amazon announced a new product today called a Dash Button. Amazon sends you a little self-stick wireless pushbutton. When you run out of a product, you just push the button and it sends a wireless signal which triggers your phone to send an order for the product.

With a little creativity, could you “re-purpose” one of these to be a wi-fi doorbell or some other kind of signaling device? A push-button wi-fi panic alarm? I’m sure it would be against the terms of service to open one up and modify it, but geeks like me wonder just what’s inside one of these little buttons.

A lot of the media are reporting that it’s a wi-fi button, but I wonder if it actually uses Bluetooth communication. Basically you press a button and the signal goes to your phone via bluebooth, and then you’re phone places an order via the Amazon app.

I wonder what it contains for a microcontroller? I expect there will be plenty more info to come once these start getting in the hands of consumers. According to their website, Amazon Prime members will be eligible receive three of them at no charge. At the moment it’s by invitation only.

What uses could you think of for a cute little wi-fi push-button transmitter?

5/11/15 Update:
http://www.amateurradio.com/inside-the-802-11bgn-amazon-dash-button/

Matt Thomas, W1MST, is the managing editor of AmateurRadio.com. Contact him at [email protected].

Daily solar report: Current Sunspot Cycle 24 Activity and Space Weather

Sunspot count: Sun Spots: 56 as of 03/30/2015
10.7-cm Radio Flux: 134 SFU (SFU=Solar Flux Units)
Estimated Planetary A-index (Ap): 5 | K-index (Kp): 2

Solar Wind: 405 km/s at 16.0 protons/cm3, Bz is 2.0 nT
(Mar 31, 2015 at 1820 UT)

X-ray Solar Flares:
6h hi [C4.7][0138Z 03/30] 24h hi [C4.7][0138Z 03/30]

Background X-ray Level, Last Six Days

Mar 30 2015 :: B6.6
Mar 29 2015 :: B9.1
Mar 28 2015 :: B7.9
Mar 27 2015 :: B5.0
Mar 26 2015 :: B4.5
Mar 25 2015 :: B5.4

Global HF Propagation Conditions for 1800Z on 31 Mar, 2015
High Latitude: Fair
Middle Latitude: Normal
Low Latitude: Normal

Geomagnetic Latitude Ranges: High: 60-90 degrees, Middle: 20-60 degrees, Low: 0-20 degrees

For live data and images, visit http://SunSpotWatch.com

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

This report has been prepared by your space weather and radio propagation reporter, Tomas ( amateur radio operator, NW7US, http://NW7US.us )

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