Great Circle Map Generator

For those of you that are interested in radio listening, particularly over long distances (AKA DXing) with even a moderately directional antenna, having a great circle map projection for  your location is a necessity.  Looking at a Mercator Projection, the normal “flat” map most are familiar with, one might come to the conclusion that due west from upstate NY lays the Washington/Oregon state boarder.  Appearances can be deceptive, bearing away at 270 degrees true (due west) from upstate NY is the California/Mexico boarder.

This is because the we live on a big sphere.  In this regard, the only place the the Mercator Projection is accurate is around the equator unless one is going due north (0 degrees) or due south (180 degrees).  The further north or south from the equator, the less accurate a flat map is.   Therefore, having a Great Circle map projection based on your location is handy for choosing the right azimuth to listen along.

As with many things, the internet provides the required tools to generate a great circle map for any location in the world.  The first thing needed is an accurate fix of your location.  This can be obtained via GPS, or, if you know how to look at a map and or satellite picture, itouchmap can be very useful.  Once you know where you are,  you can plug that information into this Great Circle Map Generator.

I saved the image as a bit map and use it as the wall paper on my computer.  That way, I just need to minimize any running programs and I can see what the correct azimuth is to any place in the world.  This is for upstate NY:

great circle projection
Great Circle Projection

Working with Surface Mount Technology (SMT)

A quick glance at almost any circuit board these days will show that almost all of the components are surface mount.  They are small rectangles or squares that sit on top of the circuit board.  This is different from the through hole components that were used for many years and are still found in older equipment.  There are radio engineers that feel that surface mount components are too hard to work on, thus the boards are not repairable.

California Amplifiers C band block down converter
California Amplifiers C band block down converter

As with anything in the engineering field, there needs to be a cost/benefit analysis.  Most computer components boards, things like NICs, modems, sound cards, VGA cards are very inexpensive and often times it would be more expensive to repair the board than it would to buy a new one.  In other situations, however, local repair of circuit boards makes good sense and can be a good learning tool.

Consoles and transmitters offer some good opportunities for local repair, provided the schematics are available.  SMT component trouble shooting is the same as through hole trouble shoots, except the components are smaller.  That is where a magnifying glass comes in handy.  I purchased a magnifying glass/light to work on SMT boards.

three diopter magnifying lamp
three diopter magnifying lamp

Soldering and unsoldering techniques are also different.  A temperature controlled soldering iron with a small tip is important.  I find the easiest way to unsolder a component is with solder wick.  Once most of the solder has been wicked up, a brief touch of the iron and the component will come off.  Small resistors and capacitors are fairly rugged, but should not be overheated.  Semiconductor components such as diodes, transistors and ICs are susceptible to heat damage and Electro Static Discharge (EDS).  A grounding wrist strap should always be used when handling semiconductor components.  Soldering iron temperature should be enough to quickly melt the solder and heat the connection surface without overheating the SMT component.  Lead free solder requires slightly higher temperatures than the traditional 60/40 rosin core.

Weller WD1 temperature controlled soldering station
Weller WD1 temperature controlled soldering station

A temperature controlled soldering station is a must.  Too much heat will damage components and boards, too little will make soldering SMT an arduous task.

Soldering supplies
Soldering supplies

Other soldering supplies include liquid flux, desoldering wick, flux remover and 55/40/5 solder.  The desoldering wick makes it easy to clean up an errant solder deposits and is the best way to desolder surface mount components.  I have had limited success using a solder pump on surface mount boards.  They do come in handy for RF MOSFETS, which have large tabs, often with liberal amounts of solder applied at the factory.

Soldering new components:

HF receiver preamp SMT board
HF receiver preamp SMT board

A typical 0.1 uf capacitor is placed on the surface mount board and ready to be soldered.  These components are all small, but I would characterize this as a medium sized one.  There are some very small diodes, ICs and other devices that require the magnifying glass to identify pins and polarity.

The best way that I have found to solder components onto a surface mount board is to use a little bit of liquid flux on the board.

Using tweezers or small needle nose pliers, place the component.

Soldering 0.1 uf bypass cap on SMT board
Soldering 0.1 uf bypass cap on SMT board

Wet the end of the soldering iron with a little bit of solder.

Using the placing tool, hold the component in place and touch one of the pads with the soldering iron.  This should tack the component in place. Solder the component to the other pad using the soldering iron and solder.  Then come back and touch up the tacked side.  I have found that 600 degrees F is a good temperature to quickly melt the solder, while not heating up the component too much.

HF receiver preamp with bypass capacitor soldered
HF receiver preamp with bypass capacitor soldered

Sorry I could not get pictures of the actually process, I don’t have enough hands to hold the soldering iron, hold the component down and take a picture.

HF preamp based on Norton 1N5109 design
HF preamp based on Norton 1N5109 design

The completed preamplifier.  I have been calling this an HF preamp, because that is its intended use.  In practice, this preamp should work well from 50 KHz up to about 75 MHz, with 3dB points at 30 KHz and 100 MHz.

Norton HF preamp schematic
Norton HF preamp Schematic

The Norton design is an inverse feed back and using the 1N5109 transistor, which has input and output impedance of 50 ohms, makes it simple to implement.  In testing, I found this unit has about 10-11 dB of gain with about 4 dB of noise.   The use of SMT makes the design stable and I didn’t see any evidence of oscillations when testing it.  More on the preamp here.   I installed it out at the base of my K9AY antenna and it can be remotely turned on and off as needed.  My main reason for wanting it is to overcome the 6.5 dB signal loss in the four port hybrid receiver coupler and transmission line I use.  Truth be told, most of the time it is off.

Last Radio Playing

Sounds like some dire prediction, but no, actually it is a good radio show heard on Shortwave, WWCR-2 to be precise.  The show, at least during the weeks that I heard it, consisted of blues and other music that you likely won’t hear anywhere else.  Allan Gray, the host, also often interviews musicians and other persons of note.  I stumbled on this show a few weeks ago while listening to 12,160 KHz on Saturday afternoon. WWCR is touted as “World Wide Christian Radio” and there are many religious shows to be sure.  They also air several secular programs like World of Radio, Golden Age of Radio, DX partyline and Ask WWCR and Info Wars and others.

Allan Gray

From reading their schedule, Last Radio Playing can be heard on WWCR-2 Tuesdays at 5pm est (5,070 KHz) , Saturdays and Sundays at 3 pm est (12,160 KHz) and on WWCR-3 at 8 pm (4,840 KHz).  WWRC is located in Nashville, TN.  They have four Continental 418 HF transmitters with a carrier power of 100 KW each.  WWCR-2 uses an azimuth of 85 degrees true and WWCR-3 uses an azimuth of 40 degrees true, both into Rhombic antennas with 14 dBi gain.

Today the show consisted of Christmas Music, which on the AM wide band receiver, sounded pretty good.  Anyway, if you are so inclined, tune in and take a listen.

Shortwave Broadcasting and the free press

WWCR wire rhombic antennas
WWCR wire rhombic antennas

Shortwave broadcasting is often overlooked as a domestic news outlet.  This is by design and is a throw back to the cold war era when shortwave broadcasting was seen as an international propagation outlet, mainly used by the VOA.  In fact, according to the Smith-Mundt Act of 1948, the Voice of America is forbidden to broadcast directly to American citizens. The intent of the legislation is to protect the American public from propaganda actions by its own government.  Nice, huh?

WRMI corner reflector
WRMI corner reflector

The way the FCC rules governing shortwave (AKA HF) broadcasting are written, the station needs to be designed and configured to transmit signals to areas outside of the US.  Any coverage within the US is considered incidental.  See also CFR 47 73 part F.

WRMI signal 50 KW 9350 KHz
WRMI signal 50 KW 9950 KHz

That being said, many of the non-VOA HF broadcasters are well received in the US.  There is nothing that is preventing a shortwave station on the west coast beaming it’s signal across the North American continent to Europe, or over the poles, etc.  These stations’ call signs start with a K or W much the same as FM and AM broadcasting stations.  Most of them are religious broadcasters, however, there are a few that offer non-religious programming or a mixture of both.

As Clear Channel lays off more staff and becomes a computer automated shell, I am beginning to think that traditional AM and FM broadcasting is on the way out.  Television news and the 24 hour news cycle has blurred the line between journalism and opinion.  Newspapers have filled the role of government watchdogs and general information sources since this country was founded.  Newspapers have fallen on hard times with many cutting investigative reporters, general reporters and or going out of business.  The internet has become the defacto information source for many people, which is fine so long as users understand its limits.

The big problem with all of this is the internet is a fragile thing, controlled by a few very large companies.  A few keystrokes and a router table is re-written to exclude a site that might have detrimental information.  Distributed Denial of Service attacks have taken down Wikileaks for days.  Collateral Wikileaks related damage occurred to Amazon.com, Visa, Mastercard and Paypal.  A few “persuasive” calls from an important government agency or official to a ISP or server company can easily take a site or multiple sites off line.   Search results can be skewed by search engines, or by large companies like BP did during the Gulf oil spill.

The FCC debates on so called “net neutrality” have yet to produce any meaningful frame work to avoid corporate and search engine censorship.  This also assumes that the government can justly regulate the internet, which, in this day and age is a stretch of the imagination.

All of this is leaving an information void.  As the saying goes, nature abhors a vacuum.

Enter Shortwave Radio.  Now, I’ll be the first to admit, there are a lot of strange things that can be heard in the shortwave broadcast band.  However, it one can separate the wheat from the chaff, some rewarding entertainment can be had.   Most of the non-government shortwave stations in the US are religious broadcasters.  There are at least three stations that offer time brokered programs, some religious and some not.  WBCQ is always a good bet.  WRMI is offering more and more non-religious programming.  WWCR also has some general programming.  While government broadcasters like the BBC, CBC and others have greatly curtailed their broadcasts to North America, this is not necessarily a bad thing, as other smaller broadcasters can be heard where the giants once roamed.

As solar cycle 24 heats up, the programming selections on any given day can vary widely. Radio Australia (ABC) has been booming in on 6020 KHz in the mornings around here.  They have an excellent country music program and I have been introduced to several songs and musicians that I would not have otherwise heard.  Today I heard a great show on Radio Australia Today about New Orleans, Ray Nagin, the aftermath of Hurricane Katrina and lots of things that haven’t aren’t normally heard here in the US.

Key to shortwave listening is the receive antenna.  One particular MF/HF receive antenna is the K9AY loop.  I have had very good luck with that antenna on both standard and international broadcast.  I have to say, I am finding fewer and fewer things to listen to on the AM band.  I have taken the opportunity to make a few circuit boards with a 10-12 dB preamp for controlling the pair of loops used in a K9AY array.  The preamp is based on a common base Norton design, which has low noise and moderate gain.  I use the preamp sparingly, the main reason for it is the 4 way hybrid splitter, which adds 6.2 dB of loss to the antenna output.  Still, I have noticed, especially on narrow bandwidth digital signals, the preamp can mean the difference between decoding a signal or not.

I am making extras, K9AY antenna systems, preamps, receiver splitters and other general shortwave receive systems, which I plan to offer for sale at a later date.  As they say, stay tuned.