Category Archives: Technical

FM DX Antenna & Tuner

I decided to try a bit of FM DX after a break of more than 20 years and
needed a new antenna.

First I tried a 7 element log periodic yagi, similar to this example but found the local FMers about 3km away swamped the whole band pretty much. So then I re-built the antenna into one of these combo yagis  which is a hybrid log periodic yagi and standard yagi, sometimes called a “logyag”.

It handles the signals from the locals much better than the straight LPY
and seems to be more directional. Mine is made from old low-band TV
antennas so only cost me some hardware and time.

Noise – A Problem Even 80 Years Ago

Noise.

Noise. (Photo credit: Wikipedia)

This interesting article forwarded from Bill Marsh was penned 80 years ago. In all that time, noise from electrical and electronic devices has grown even worse.

 

A Ferrite Shielded Loop – Kiwi Style

fsl3

Bill Marsh has been experimenting with the ferrite sleeved loop design and has come up with a clever design. You can read the full article here.

Coax Loop Revision

Bill Marsh has been experimenting further with his coax loop for MW and the X-band. Here are the results:

X-BAND LOOP NUMBER 2

Rockwork Cliff DXpedition

garydebock

Gary DeBock with an FSL at Rockwork.

Washington state DXer Gary DeBock (above) who recently joined the  League has posted this report of a DXpedition to his favourite cliff-side location on the northern Oregon coast last month. Thanks to Paul Rawdon for reporting this to the DX Dialog user-group.

X-Band Coax Loop

xloop1Bill Marsh Jnr. has recently completed his X-band coaxial loop antenna (tunes 550-1700kHz). The full article appears here.

New Articles Added

Using Standard Signals From WWV

wwv1Historical article:

Using Standard Signals From WWV

Possibly not all readers realise that very precise standards of time and frequency are available on the short-wave bands to anyone possessing a suitable receiver. This paper, prepared by engineers of the Aerovox Corporation, summarises the present transmissions and suggests methods by which the information can be used.

THE standard time and frequency transmissions of the National Bureau of Standards radio stations WWV and WWVH provide an invaluable service to laboratories and individual experimenters throughout the world.
Extremely precise audio and radio frequency standards, as well as accurate time intervals and radio frequency propagation warnings, are placed at the disposal of anyone having a receiver capable of tuning to one or more of the transmitting frequencies.

The Ionosphere And Its Relation to Radio Frequency

 

 radhob2

Historical article:

A summary of a lecture delivered to the Wireless Institute of Australia
on June 15, 1939, this article will be welcomed by all who are interested
in fading and skip-distance transmission on various frequencies.

By R. H. Healy, D.Sc., E. inst. P.

1. INTRODUCTION

SHORT-WAVE circuits operating between wave-lengths of 10 and 100m. (30 and 3 mcs.) are dependent, in the majority of cases, on reflections from the ionised regions or layers of the atmosphere. In the absence of these reflections, communications by means of the ground ray alone is only possible up to comparatively short distances, the actual distance depending on such factors as the earth resistivity, the wave-length, and the height of the transmitter and receiver above earth.

Stars Control Wave-Length

radhob

 Historical article:

STARS CONTROL WAVE-LENGTH;

USED TO CHECK TUNING FORK

An interesting development in checking the frequencies of broadcasting stations is announced by the A.W.A. Research Laboratory

THE stars in the heavens have been harnessed to prevent overlapping among broadcasting stations. By their aid, complaints of interference between any of the 121 stations in Australia have been practically eliminated.

To test whether a station is on its wave-length, the scientific staff at the A.W.A. Research Laboratory, Ashfield, employs a tuning fork of high-grade Elinvar steel. This fork, when vibrating, has a natural frequency of 1000 cycles per second, and when its frequency is compared with the frequency of a broadcast station or control equipment in course of manufacture, the slightest variation from an allotted frequency or wave-length is detected.

Practical Details of … “Eliminoise” Aerial Equipment

elinimoise

Historical article:

Typical Sales Advertisement from

The N.Z. Radio Times

February 2, 1937

It is generally agreed that if a receiver has to be operated where interference is directly radiated, the most effective way of improving reception is to attend to the aerial; the active span should be erected as far from any metallic conductor as possible, and the down lead which is incapable of picking up any radio voltages be used for connecting the aerial to the receiver.

High Efficiency Aerial For Shortwaves – Historical

 

hef1

HIGH EFFICIENCY AERIAL FOR SHORT WAVES

HERE is a short wave antenna that has helped me very much in my SWL work. I believe it is an original idea, for I have never seen or heard of one like it. It occurred to me when I was trying to figure out a way to have good directional antenna (all directions) without having to have a separate antenna for each direction. It has worked wonderfully well for the past six months, so I thought that others interested in the same field might like to try it.

Wave Traps – Historical Article

wt2

 

WAVE TRAPS

FOR INCREASING R.F. GAIN

By

R. J. A. LITTLE, A.M.I.R.E. South Melbourne

From – The Australasian Radio Times – July 1947

A WAVE TRAP can be defined as a circuit containing at least one condenser and one coil wired in series or parallel to form a tuned circuit. A most common form of wave trap is one utilising a parallel tuned circuit.

Great Circle Gadget

Radio World

Historical Article: Tells You Where To Point Your Directional Aerial

Gary DeBock & The Ferrite Sleeve Loop

FSL15+in+US+De+BockThanks to Tony King reporting on the DX Dialog reflector, here is a photo of Gary DeBock with his invention, the Ferrite Sleeve Loop. “Gary DeBock’s latest creation with which he is scoring many NZ stations on his Tecsun PL380. Probably about 200 ferrite rods on this “sausage roll” .pic attached.  He’s in the right uniform, and his PL380 lives in an NZ emblazoned mobile phone pouch I sent him last year.” Rumour has it one or two Kiwis are building them!

And also from Gary is a Youtube video of his antenna picking up trans-Pacific DX from New Zealand.

Solving Noise Problems In The Modern Home

toroidsJim Brown K9YC is the author of an excellent guide to solving RFI issues around the radio shack. His very useful article “A Ham’s Guide to RFI, Ferrites, Baluns, and Audio Interfacing” has much information useful to SWLs looking for a way to reduce noise and there are a lot of instances where the noise-source is in the home.  You’ll find a lot of interesting material on Jim’s website.

 

Stop That Noise!

Historical article from Lamphouse Annual 1947-48

 

Lamphouse Annual 1947-48 CoverSTOP THAT NOISE!

MANY excellent programmes are ruined by man-made interference. In order to locate the source of interference you should endeavour to obtain some clue to possible causes, and, by the process of elimination, determine the electrical system in which the trouble originates.

The local Radio Inspector of the Post and Telegraph Department is always willing to investigate complaints of continued interference, but before calling on his assistance you should endeavour to eliminate the possibility of the trouble being in your own receiving set, your aerial and earth system, or caused by some electrical appliance or circuit in your own home.

Aerial & Earth Systems 1948

lamphouse

Aerial and Earth Systems

By “Starlite”

From the 1948/49 “Lamphouse” Annual

The early pioneers of radio were once faced by a very serious problem. Their crude attempts at transmission were being held up as the range achieved was extremely limited. Someone got the bright idea of suspending a piece of wire in the air. Thus the aerial was born. The earth was the logical conclusion. Radio transmission and reception experiments increased in efficiency.

The same holds good today.

Is it a bird? Is it a plane? No… it’s an FSL!

fsl

Remember the good old ferrite loopstick antenna? Well, the FSL (ferrite sleeve loop) is a loopstick on steroids.  Gary DeBock is one of many hobbyists who have been experimenting with these imposing antennas, sort of the boat anchor of aerials! His interesting article appears on Colin Newall’s dxer.ca site.

 

In the Market for a New “Pre-loved” Receiver?

r1000

In New Zealand, the majority of used shortwave radios are bought and sold via the on-line auction site TradeMe.

But which of them are cherries and which are lemons? There is a useful guide on the dxing.com website. The list of receivers rated appear on this list. The receivers ratings using ‘H’s instead of stars, seem to reflect general opinion as far as the tried and true experience of NZ DXers goes, with one exception. The Yaesu FRG7 receives a top-rank, however they pale in comparison to the actual performance of even some HHH rated sets.

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