Category Archives: Mediumwave

Radio World: Construct an EAS Receive Loop Antenna

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The completed antenna, showing the F-connector on the tee box. (Source: Radio World)

Many thanks to SWLing Post contributor, Kris Partridge, who shares the following antenna construction article from Radio World:

Ken Beckwith is a field engineer with EMF based in Nebraska. Being a hands-on engineer, Ken has done his share of construction over the years. One of his projects was the construction of an octagonal-shaped AM loop EAS antenna using PVC pipe.

[…]The antenna has a broad coverage angle with a deep null when the antenna is broadside to the signal. Aim the “edge” of the loop toward the AM station you want to receive. The strongest signal will be received when the antenna end or edge is pointing to the signal source. The antenna can be mounted on a mast with U-bolts, hose clamps or whatever else works.

Here’s the construction parts list:

A 10-foot length of 3/4-inch diameter, schedule 40 PVC conduit cut into the following lengths:

2 – 4-inch
1 – 2-inch
1 – 2-1/4-inch
2 – 2-1/8-inch
6 – 9-1/2-inch
1 – 23-1/4-inch

Whatever is left over can be discarded, but before making your cuts, cut the flared end off, so all cuts are even.

1 –  3/4-inch 90 degree elbow
2 – 3/4-inch tee
8 – 3/4-inch 45 degree elbows
1 – 3/4-inch cap
1 – 3/4-inch tee box, plastic, with weatherproof gasket
1 – 7-foot piece of Belden 8777 or other three-pair shielded cable
3 – 7-foot single-pair shielded cables can substitute for Belden 8777
PVC primer and cement
Wire nuts or other connectors
1 – 3/8-inch ring terminal
F connector barrel with nut

[…]

Click here to read the article which contains step-by-step instructions.

Radio Vanuatu: New shortwave and mediumwave service through infrastructure upgrade

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(Source: Vanuatu Broadcasting & Television Corporation via Peter Marks)

RADIO VANUATU CAPITAL DEVELOPMENT WORK BEGINS

With the support of the Government of Vanuatu, the Vanuatu Broadcasting & Television
Corporation (VBTC) has begun work this month on a 942 million vatu (US$8.1m)
infrastructure upgrade to improve radio and free-to-air television service throughout
Vanuatu.

The first phase involves the design, installation and commissioning of a new shortwave (HF)
and medium wave (MF) service for Radio Vanuatu, the country’s public radio service. Costing
for phase one will be in excess of 242 million vatu (US$2.2m) and is funded by the
Government of Vanuatu. Following the improvements to shortwave and medium wave
services, VBTC will also undertake technical work to strengthen the coverage and reliability
of its FM services.

A 10kw MF Nautel transmitter imported out of Canada and a 10kw HF transmitter
manufactured by Hanjin Electronics of South Korea will be installed at VBTC’s major public
service transmission site at Emten Lagoon on Efate. Both transmitters will be commissioned
before the end of 2019.

The second phase, beginning early 2020, will reopen Radio Vanuatu’s medium wave radio
transmission facilities at St Michelle in Luganville on the island of Santo. This will provide AM
service to provinces in the top half of Vanuatu at a cost in excess of 300 million vatu
(US$2.5m).

The third phase will expand the national television free-to-air service, Television Blong
Vanuatu, along with a new digital television service. This final phase will cost an estimated
400 million vatu (US$3.5m).

Prime Minister Charlot Salwai Tabimasmas launched the capital development upgrade at a
special function attended by cabinet ministers, senior members of the public service,
members of the diplomatic corps and members of Vanuatu’s business and non-profit
communities on Friday September 20 in Port Vila before he departed the country to attend
the UN General Assembly in New York.

In his address, the Prime Ministerspoke atlength about the importance to Vanuatu of having
a strong national public radio and television broadcasting service and announced assistance
from Vanuatu’s development partners to help achieve this objective.

The Government of Australia funded the scoping study for the radio upgrade project and is
providing funding support to implement the strategic reform programme of VBTC which the
Prime Minister said is making good progress.

“I’m also happy to announce that the New Zealand Government is keen to support the
second stage of the Radio Vanuatu technical infrastructure upgrade while China is
considering my request to support the upgrade of Television Blong Vanuatu’s technical
infrastructure.”

Meanwhile Kordia New Zealand Limited has been awarded the contract to project manage,
design, install and commission the new radio transmission facilities beginning with the
facilities at Emten Lagoon outside Port Vila.

VBTC Chief Executive Officer, Francis Herman said that “Kordia has extensive experience in
the broadcasting and telecommunications industry in the Pacific, and recently completed a
major project in Samoa for State-owned Radio 2AP funded by the Australian Government”.
“We’ve worked hard with Kordia and a number of other technical experts to investigate the
most efficient and sustainable transmission solution for Vanuatu taking into account the
inclement weather, and the need to keep operating costs affordable.”

The shortwave service, which will be commissioned before the end of this year, will provide
national radio coverage to the 82 islands spread spanning 1,300 kilometres between the
most northern and southern islands.

“Our role as Vanuatu’s national broadcasting service is centered on helping create an
informed public opinion so our people can contribute more effectively to national
development”, Herman added.

“VBTC has struggled to remain relevant over the past decade because its technical
infrastructure was obsolete and badly neglected making it challenging for us to provide an
efficient, reliable, and responsive national radio and television service.”

Alongside the infrastructure upgrade, is an extensive programme to strengthen the technical
capacity of Vanuatu’s broadcast technicians along with a long-term maintenance regime to
expand the life of the equipment.

September 23, 2019

David reviews and compares the MLA-30 magnetic loop antenna

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Many thanks to SWLing Post contributor, David Day (N1DAY), who has completed a thorough review of the MLA-30 loop antenna. In this review, he compares the MLA to the Wellbrook ALA1530-LF and a 30 foot square ground loop antenna.

In short, he finds that the MLA-30 performs fairly well on the AM broadcast/mediumwave band, but can’t compete with the Wellbrook otherwise–especially in terms of noise floor. David also noted that “the MLA-30 had a very serious issue with IMD and in some cases, stations that were clearly heard with both the Wellbrook and the ground loop were totally obliterated by IMD when switching to the MLA-30.”.

Click here to read David’s full review on his blog, Ham Signal. 

Click here to view the MLA-30 on eBay.

C. Crane CCRadio3 now shipping

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Many thanks to SWLing Post contributor, Steve Lebkuecher, who notes that C. Crane is now shipping the CCRadio3:

Click here to read our review of the CCRadio3—a unit we consider to be one of the best full-sized AM radios currently on the market.

Click here to check out the CCRadio3 at C. Crane.

AirSpy HF+ Discovery: First Impressions on Medium Wave vs. Elad FDM-DUOr

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The highly anticipated AirSpy HF+ Discovery SDR has been in the hands of early adopters for about two weeks–and I’ve seen nothing but positive comments!

After a long run (2007-2013) with a Microtelecom Perseus, my SDR of choice became the Elad FDM-S2, and more recently an Elad FDM-DUOr “hybrid” SDR receiver. The two Elads have the same core processing components and identical performance when the DUOr is connected via SDR software.

This week I’ve compared the HF+ Discovery ($169) against the FDM-DUOr ($899) using Studio 1 software and identical modes & settings. The following video features the radios’ performance on a crowded daytime medium wave band from suburban Seattle-Tacoma USA.

https://www.youtube.com/watch?v=vkQQeF2edCU

Click here to view on YouTube.

Notes:

  • Software used is two “instances” of Studio 1, version 1.06e
  • Antenna is an east-west oriented Wellbrook ALA1530LNP Imperium loop
  • Mode, filter bandwidth, AGC, etc. are the same for each radio
  • 768 kHz sampling bandwidth used for both receivers

Stations tuned are:

  • 1320 KXRO Aberdeen WA, 74 miles @ 5 kW (in-line with antenna)
  • 1110 Oak Harbor WA, 78 miles @ 500 watts (in antenna’s null)
  • 1040 CKST Vancouver BC, 147 miles @ 50 kW (in antenna’s null)
  • 1430 KBRC Mt. Vernon WA, 85 miles @ 5 kW (in antenna’s null)
  • 750 KXTG Portland OR, 118 miles @ 50 kW (in antenna’s null)

I purposely sought out signals difficult to hear in the presence of powerhouse stations. Only 1320 kXRO (in-line with my antenna) and 750 KXTG are what you might consider average or fair quality signals. Headphones are recommended for most of these, particularly 1040 kHz.

You’ll note that the pass band has been “pulled” over the edge of the carrier frequency by a few hundred Hertz. This is an excellent trick that can often reduce noise and/or improve intelligibility. It’s a feature unique to Perseus, Studio 1, and SDRuno software; it works in sideband modes and in selectable sideband Sync AM (SAM) mode.

After listening to the signal comparisons, what are your thoughts on the HF+ Discovery? Please leave your comments below.

Guy Atkins is a Sr. Graphic Designer for T-Mobile and lives near Seattle, Washington.  He’s a regular contributor to the SWLing Post.

Ron is impressed with the PK Loop Mini (A-LOOP-MTAM)

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Many thanks to SWLing Post contributor, Ron, who shares the following review of the PK Loop Mini (A-LOOP-MTAM):

Standard PK Loose-Coupled Loops (the “A” series) are 14 inches in diameter…they are
for use with a receiver having a built-in ferrite bar antenna.

Don’t think they’re not capable of serious DX…a few years ago a friend in Texas
snagged and recorded France Inter (162 kHz) on a 14 inch standard PK LW
loop using a Sony 7600GR.

But this is about the PK Mini 10 inch loop for Medium Wave (there are none for
other ranges).

The build quality is superb as with all PK loops. The band has two ranges: 525 to
710 and 710 to about 1720 kHz. Paul Karlstrand uses a unique design consisting
of flat computer cable and a custom made circuit board to connect the turns
end-to-end.

The low end simply switches in a fixed capacitor across the variable to lower the
frequency.

The Mini has 25% less sensitivity than the standard 14 inch loop according to the website.
Currently it can be had for $66 USD delivered to your door from Melbourne…this one
was ordered on a Monday and showed up a week later,which is outstanding considering
it had to clear customs in NYC.

Performance is virtually identical with the Tecsun or Terk loops, which are 9 inch loops.
So why buy a PK?

You get what you pay for, or not…the PK is fairly robust compared to the Tecsun or Terk.
It’s made to last and it’s a PK Loop.

Here are some links for comparison purposes:

If you wish to enhance your loop try co-coupling it to your receiver with a Q-Stick :

http://dxtools.com/QStick.htm

Thank you, Ron, for sharing your experience with the PK Loop Mini. It certainly sounds like an excellent option for travelers and, like you, I agree that the construction quality is superb!

Click here to check out the PK Loop website.

Radio World: History of Directional AM Broadcast Antennas

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Many thanks to SWLing Post contributor, Marty, who shares the following article by John Schneider in Radio World:

In the early years of AM radio broadcasting, all stations utilized non-directional antennas. Most all of these were wire antennas suspended between towers or buildings. Interference, especially at night, was severe. An interfering signal of 5% or less in signal strength was enough to disrupt reception of the desired station, and if the frequencies of the two stations were slightly separated, there would be a heterodyne beat note. As a result, only a few widely-spaced stations could operate on each of the AM broadcast channels in the entire country at night. This limited the number of stations that could coexist to about 500 nationwide, with many of them sharing time on a single frequency.

As antenna technologies were developed and improved in the early 1930s, a few progressive stations began experimenting with multi-element directional arrays. This approach offered two attractive benefits: 1) It could reduce radiation towards other stations on the same or adjacent frequencies, permitting more stations to share a frequency; and 2) a broadcaster could direct more signal towards the desired coverage area, and away from wasted areas such as open water in the case of coastal stations.

WFLA-WSUN

The first known use of a directional antenna was by a pair of stations in Tampa/St. Petersburg, Fla. In 1927, the Clearwater Chamber of Commerce acquired station WGHB and changed the call sign to WFLA. A companion station, WSUN, was operated by the St. Petersburg Chamber of Commerce. The two stations shared the frequency of 900 kHz, broadcasting on alternate evenings to promote tourism and business opportunities in their respective communities. In reality, they operated with two station licenses, but there was only one transmitter and one antenna.[…]

Click here to to continue reading the full article in Radio World.