Category Archives: Accessories

Southgate ARC: What Is a Balun and How to Make One Cheaply

(Source: Southgate ARC)

Ham Radio – What Is a Balun and How to Make One Cheaply

A Balun is a transformer which allows coaxial cable, which is an unbalanced lead to be connected to a balanced load, for example a resonant aerial.

The 1:1 balun is often called a choke balun, it works by eliminating Radio Frequency currents flowing on the outside of your coaxial cable, this is important because it prevents the pattern of the dipole becoming distorted and prevents the braid of the coaxial cable radiating.

Connecting coax to your resonant dipole which can be configured in a V shape or in a sloping fashion, however serious power loss and feeder radiation can occur without the use of a balun transformer. No one wants to induce Radio Frequency currents into Television receivers or Broadcast equipment as it may result in disputes with neighbours and could possibly lead to your station having to close down. Try to keep the centre of your aerial away from buildings as it may induce Radio currents into the mains wiring.

Building a choke is not difficult all you need is some plastic pipe available from many Do It Yourself outlets and warehouses. I use a length of about 1 foot of plastic pipe and 21 feet of coaxial cable, the length of the pipe and diameter is chosen because it works well if using R-G-5-8 coax the ends of the pipe can be sealed after placing a SO-239 connector for your coaxial lead. I use two bolts and solder tags at the other end of the pipe to connect the ends of the dipole to the choke.

When wrapping your coax around the pipe don’t use too much force as it may damage the inner braid and space the turns away from each other by a millimetre or two. R-G-2-1-3 coax around 21 feet used with 5 inch pipe will handle 400 watts pf power. Wire ties can be used to hold the turns together along the length of the pipe. Using these measurements your choke will cover all of the ham radio bands from 1.8 Megahertz through to 28 Megahertz and will keep the radiation pattern.

Using a dummy load connected to the choke and transmitting 100 watts from my transmitter indicated an S.W.R. readings of around 1.5 to 1 at 3.5 Megahertz when testing 28 Megahertz the S.W.R. reading came down to 1.1 to 1 which is an excellent match. Using the choke as it should be at the feed point of a dipole cut for 40 metres give an S.W.R. reading of 1.2 to 1. The highest reading was 1.5 to 1 when using 18 Megahertz but the rest of the High frequency bands gave me very acceptable matching.

By
John Allsopp G4YDM
https://g4ydm.blogspot.co.uk/

Article Source:
http://EzineArticles.com/expert/John_Allsopp/1925417

Article Source:
http://EzineArticles.com/9615600

Radio Wall Clocks: Mario’s eBay find

Many thanks to SWLing Post contributor, Mario Filippi (N2HUN), who writes:

Hi Thomas,

These have been popping up on eBay, reasonable price, with face markings just like an old shortwave radio dial.

Click here to view Zenith wall clock.

Pretty nice gift for the SWL who has everything!

Click here to view Sparton wall clock.

Have a good day and weekend!

Thank you, Mario! Those are nice clocks and, as you say, rather affordable at $26.49 shipped! I like the fact they also include 24 hour markings.

Your message lead me down a path to search eBay for other radio wall clocks. There are hundreds out there! I found that searching with the term “ham radio wall clock” seemed to work best.

WRTH 2017: A look inside

I received my copy of the 2017 World Radio and TV Handbook (WRTH) directly from the publisher last week, just prior to Christmas holiday ravels. As I mention every year, I look forward to receiving this excellent staple radio reference guide–and this is their 71st edition!

WRTH’s team of noted DXers from around the world curate frequencies and broadcaster information by region; while I’m not sure how they orchestrate all of this, the end result is truly a symphony of radio information. In addition to broadcaster listings, WRTH’s radio reviews, feature articles, and annual HF report make for excellent reading.

But the WRTH isn’t just a frequency guide: the publication always devotes the first sixty or so pages to articles relating to various aspects of the radio hobby. Following, I offer a quick overview of these.

The first article always features a WRTH contributor:  this year, WRTH’s International Editor, Sean Gilbert, tells us what sparked his interested in the hobby and what lead to his career with WRTH which started in 2000.

The second set of articles is always my favorite: WRTH receiver reviews.

This year, WRTH begins with a review of the Icom IC-7300 general coverage transceiver.  They also review the Reuter Elektronik RDR55D, and re-visit the SDRplay RSP1. Following radio reviews, they evaluate the excellent Wellbrook ALA1530LNP magnetic loop antenna and the Bonito AAS300 3 way active RF splitter.

The following article focuses on one of my favorite shortwave broadcasters, The Mighty KBC. WRTH contributor, Max van Arnhem traces the broadcaster’s history and gives us a little insight about the people behind this music powerhouse. If you’re a KBC fan, you’re in for a treat!

I was very happy to find that the following feature article explores the world of Remote Reception. No doubt, remote listening is becoming one the most accessible ways many of us discover and enjoy our hobby today–especially as it can be difficult for some of us to fight urban radio interference.

Following this, WRTH writer, Hans Johnson, features an article on CKZN St. John’s Newfoundland.  In this short article, Johnson covers the history and mission of this shortwave relay, dating back to the days when Newfoundland was a British dominion. Looking forward, Johnson notes that the CBC intend to not only continue this service directed at Labrador’s most remote areas, but it intends to replace their 1 kW Elcom Bauer transmitter in the coming years. This pleases me to no end as I’ve always loved snagging this particular relay of CFGB from my home here in North Carolina.

Next, DXer Rob Shepard writes about his travels in South America and the Pacific. Being an avid traveller myself, I love reading about others’ adventures across the globe with radio. Shepard even notes some catches from the Queen Mary II. I’ve never had the chance to do DXing while maritime mobile, but I hope to someday.

The following article features Danish radio enthusiast, Vagn Fentz, who has collaborated with WRTH since one of its very first editions. His radio history starts back when he was a schoolboy in Denmark during WWII, listening to the radio in secret. His story gives us insight into both his own world and that of the WRTH over the years.

Next, Michael Pütz outlines the progress, so far, of setting up an HF disaster relief radio network: the IRDR Project. If you haven’t heard of the IRDR project, this article makes for a great primer and also speaks to the potential future of a radio network that could have major positive impact over vast regions in the wake of disaster.

The final article–a tradition–is the WRTH  HF propagation report/forecast by Ulf-Peter Hoppe. Always an informative read (despite the fact we’re heading into a solar minimum).

The 71st is another fantastic edition of the World Radio TV Handbook. I’ve never been disappointed with WRTH, in truth. Their publishing standards are such that the quality of their reviews, their writing, and (most importantly) their broadcast listings are simply unparalleled.

For DXers who collect QSL cards, you’ll find that broadcaster contact information in WRTH is often more up-to-date than a broadcaster’s own website. When readers contact me asking for QSL information from an obscure broadcaster, the first place I search is the current WRTH. Remember: their information is based on volunteer contributors who specialize in specific regions of the world–the most knowledgeable regional DXers keep this publication accurate.

Purchase your copy of WRTH 2017 directly from WRTH’s publishers, or from a distributor like Universal Radio (US) and Amazon.com (US), Radio HF (Canada), or BookDepository.com (International).

A preliminary review of the PK Loop C-LOOP-HDSW6-18

eecraft-kx3-pk-loop

The Elecraft KX3 and the PK Loop C-LOOP-HDSW6-18

Over the past year, a number of SWLing Post readers have asked me to review the PK Loop portable magnetic loop antenna produced by Paul Karlstrand in Australia.

I finally caved in and purchased one.

I ordered the shortwave version of the loop, the  C-LOOP-HDSW6-18 in early November and received it about one week later.

sony-sw100-pk-loop

The Sony SW100 tuned to WBCQ.

I was first introduced to this antenna by SWLing Post contributor, Mark Fahey, who brought it to the SWL Fest and our 2015 PARI DXpedition.

Mark has taken his PK Loops (both the shortwave and mediumwave models) on his numerous travels around the world. He finds that they’re relatively effective portable antennas in RFI-dense environments like hotels and guest houses. They’re better at mitigating RFI than, say, portable wire antennas or telescopic whips.

Mark hooks up his portable SDR to the PK Loop and makes spectrum recordings (wideband recordings)–from, say, his hotel room in Kuala Lumpur–then takes the recording back home to listen and tune at his leisure via his laptop or tablet PC.  While I’ve certainly made spectrum recordings while travelling in the past, the appeal of such a portable loop antenna is what finally caused me to pull the trigger.

Overview

pk-loop

The PK Loop is a small loop antenna–measuring about 12″ in diameter. It’s encased in UV-stabilized PVC conduit and the matching box also seems to be made of PVC. It feels very durable and can, no doubt, even survive the wildest of luggage handling.

The PK Loop has an attached battery 9V battery holder, but can actually be powered by any 9-18 volt DC supply. Current consumption is less than 15 mA. On the matching box, you’ll find a tuning knob, a BNC connector, DC power in port and a HI/LOW gain switch. My loop shipped with a 2 meter BNC-BNC Cable, 3.5mm adapter, and DC Power lead to open ends.

Operation

Operating the loop is very simple:

  1. Power the antenna with a 9V battery or other DC source
  2. Chose either the high or low gain setting
  3. Place it on a stable surface (height from the ground is not a critical issue, but you should avoid placing it next to noisy electronics or mobile phones)
  4. Connect the PK Loop to your receiver’s antenna jack with the supplied cable
  5. Turn on your receiver to the desired meter band, then adjust the loop’s tuning knob until you hear the signal level peak
  6. Start listening, keeping in mind that as you tune around the band you may need to adjust the loop’s tuning knob for maximum gain

Loop antennas, in general, are fairly narrow-band and–unlike a Wellbrook or Pixel Loop–manual adjustments need to be made with the tuning knob to match the PK Loop as you scan across bands.

Still, I see why Mark favors the PK Loop for spectrum recordings: the bandwidth is wide enough that if I tune the loop to the middle of the 31 meter band, for example, it does a fine job covering the entire band.

On the air

pk-loop-kx2-sw100

My free time has been very limited since receiving the PK Loop earlier this month, but over Thanksgiving holiday, I took it to my family’s home that has relatively high RFI levels.

The following are a couple of videos I made with my Moto X smartphone. I’ll be the first to admit that these are not the best videos–I had no tripod and the Moto’s microphone leaves much to be desired–but I think you’ll still get the idea of how well the PK Loop works.

With the Sony SW100

Click here to watch on YouTube.

With the Elecraft KX2

Click here to watch on YouTube.

So far, I’m very pleased with the PK Loop. It does seem to mitigate noise better than other portable antennas I’ve used in the past and certainly improves my SW100’s reception. It makes SWLing with the Elecraft KX2 or KX3 easy and convenient.

One word of caution: if you use the PK Loop with a transceiver like the KX2, please turn off the ATU, and set the power level to 0W before using. The PK Loop is receive-only and will not handle any RF power.

Note that with the SW100, I have only used the PK Loop’s low gain setting. I’m a little nervous about overloading the SW100, so do not plan to use the high gain setting. The Elecraft KX2 seems happy to handle either gain setting: I imagine this will be the case with most general coverage transceivers and tabletop receivers.

More to come!

In a couple of weeks, I’ll be staying in a hotel room (likely with inoperable windows and heavy RFI) so I will attempt to put the loop through its paces and compare it with my radio’s built-in antenna.  Stay tuned!

Post readers: have you used the PK Loop or other similar portable/travel antennas? Please comment!

Click here to view PK’s Loop antennas on Paul Karlstrand’s website.

Paul also sells his antennas and ships internationally on eBay–click here to view the selection.

pks-loops

Holiday Deals: GigaParts

nov-black-friday-cyber-monday-sale-topper3-nextopia

I just discovered that GigaParts is also hosting a Black Friday/Cyber Monday sale–possibly the most extensive among radio retailers.  They have a large inventory of radios and accessories and GigaParts is a trusted retailer.

Click here to view the sale at GigaParts.