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Radio Propagations


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My Thoughts on...

If I had a dollar for every time I have heard someone make the remark “the bands are dead” I’d have enough to purchase a second transceiver.  The bands are not “dead” although signal levels are down and DX isn’t as strong as it was a few months back or even last year perhaps, but the bands are in fact alive and working.

The problem isn’t the bands being dead, but instead it’s most likely your operating style, not using the right setup, and not working the propagation correctly.  Now I’m sure a lot of operators are going to say "sure the bands are not dead if you have a big antenna system and a high power amplifier" but the fact of the matter is you don’t need a “big gun” station with the latest greatest high gain beam antenna and run at legal limits to make good contacts.

Just a modest station setup and proper operating style can yield you a lot of really good DX contacts and a modest setup doesn’t need to be expensive.  You do not have to have a massive beam on a tall tower and you don’t need to run legal limit power to do it either. 

In fact, you can work good DX even with poor or fair band conditions that other operators call “dead” with a simple wire antenna system and a power range of 100-700 watts, and it all comes down to knowing how to properly operate.  I’m no “big gun” DX station, not even close to being one, but I work DX and a pretty fair amount of it.

Just using a simple setup, I actually make more contacts than a lot of operators I know who have much more invested into their station setups that I ever will be able to have, such as big beam antennas on tall towers, 1.5 KW legal limit amplifiers, and transceivers costing over $3,000.  Sure that all sounds impressive and would be nice to have, but it doesn’t guarantee you’ll work more DX than my modest setup using proper operating techniques.

To clarify what I am calling a modest station setup here is a breakdown of my HF equipment:

1) Antennas:

I use two very simple basic low profile and semi-stealth antennas because I live on a small lot that even a standard 80 meter dipole won’t fit on.  The first is a 43-foot vertical antenna for which I took a cheaper route and picked up an original S9 43-foot vertical.  LDG Electronics purchased the S9 Antennas company a year or so ago but they are still made the same, which is basically a 43-foot length of green fiberglass mast sections that telescopes out and contains a wire running the entire length inside and exiting near the bottom section for attachment to your feed line.  The green color makes it hard to see among the trees.

The second is what I have been referring to lately as a modified L wire antenna.  Making one is a cheap and simple project that can yield very good results if you live on a small lot like mine and wish to work the 80 or 160 meter bands from time to time.  It can be tuned 160-10 meters with good results on 80-15 meters.

Both antennas are fed using good quality LMR 400 coax.  The 43-foot vertical uses a 4:1 unun and the modified L uses a 1:1 line isolator.  Both the unun and isolator are made by Balun Designs.  Both antennas have buried ground radials.

2) I use a manual tuner made by Palstar Inc. although it is now an obsolete model AT1KP.

3) I run a homebrew amplifier using a single Russian GI7BT tube which produces roughly 600 watts.

4) The transceiver is a Flex SDR 3000.

There is nothing special with the setup above, yet I make DX contacts almost every time I am operating.

There are a few things that can help you get the most out of making good contacts that won’t cost you much, and some that are even free.

In order to make those contacts you first need to hear them and this refers to the statement “if you can’t hear them, you can’t work them”.  Sure, a big beam antenna on a tall tower could help a lot, but there are simple things that you can do that help with receiving signals that you might not normally hear.

Lower your noise floor!  A lower noise floor makes weaker signals easier to copy and there are several things you can try to get your noise floor lower.  Use an antenna that is less prone to noise to begin with and avoid trapped verticals if at all possible especially in areas with many power lines and close neighbors.  Many times the statement “verticals are more noisy on receive than a beam or horizontal dipole” has been made, but that isn’t always true and if setup properly you might be surprised they can have less noise than a dipole and provide better coverage.

Although I previously said I have a 43-foot vertical and it works rather well, it does not however have traps.  It has a good RF ground, is fed at the base with a good unun which by design can help reduce noise, and is followed by a lighting arrestor that is of the blocking/shunting type which constantly drains the feed line center conductor to ground resulting in lower noise.  The feed line is well shielded LMR 400 which is buried to help shield it from noise as well.  Once inside the station, the coax is attached to a RF line isolator which helps reduce stray RF on the feed line, then it connects to the tuner.  All patch cables are made from LMR 400, and line isolators are in place between the transceiver and amplifier and from the amplifier to the tuner.

Ground all your equipment to a common point!  My tuner, amplifier, rig, and computer are attached to a ground bus via ground straps and I found this can also help in reducing noise.

Try to stay away from inferior switching power supplies and “wall warts” that can produce birdies and other RF hash.  On some computers you may also find you are better off with a wireless card or switching brands of the network card used on the system.   Another issue I have noticed becoming more common lately is the nasty RF hash producing power supplies used by some off-the-shelf computer companies.  If you have a lot of noise on your receiver turn things off near you one by one and see if your noise is reduced.

My transceiver has a very sensitive receiver and a low noise floor to start with, but overall, the above suggestions will result in lower noise on receive making it easier to copy weak signals.

Now that the receiving side is working well we can move onto the transmitting side and again antennas play an important role in making sure your radiated signal is going to be heard.  

The antenna you're going to use on a particular band to work DX or long haul stateside contacts needs to provide you with a low take-off angle.  Most verticals have low take-off angles making them ideal for working DX and as such they can be placed lower to the ground than a horizontal dipole or a beam antenna.  (There is always an exception, and a quad design antenna such as a quad loop or beam can perform well at lower heights than a yagi style).

A vertical doesn’t need to be rotated because it is omni-directional, which allows you to hear well from all directions.  However, a beam antenna can reduce noise on receive by attenuating signals from the sides and back, and also concentrate a signal in a particular direction.  However, if it is not high enough you could be better off with a vertical to work DX and the same can be said for low hanging horizontal dipoles which are better for close in, to medium range.  If you’re working with a wire dipole and can’t get the height needed for DX, try placing it in an inverted v configuration which will provide a more vertical radiation pattern and lower the take-off angle.  There is a lot of good information on take-off angles which can be found on several websites also take a look at http://dx-antennas.com/ and choose the topic “Height versus take off angle”.   Also, a nice PDF article to understanding antennas can be found at http://www.hamuniverse.com/basicantennas.pdf

Both the vertical and modified L that I use have low take-off angles and I’d also like to point out that neither of these two antennas are resonant and thus require a tuner.

A little extra power can help, but you don’t need to run legal limit to make DX contacts. Even QRP with the right antenna and operating style can get you good results even when others claim the bands are “dead”.  500-700 watts will provide you with enough power to make good contacts when band conditions are not their best, and proper operating style with the right antenna can do wonders for what others call a “dead band”.  

I can think of examples I heard in regards to “dead bands” lately with the recent Field Day and the OHIO QSO Party when several claims were made that the bands were dead.  Yet with fewer transceivers on the air than other area clubs, we ran up the number of contacts with never making the statement that “the bands are dead”, and in fact there were several occasions when we managed to keep a steady stream of contacts flowing.

Working long haul state side and DX:  

So, now you can hear the guys calling “CQ” or “CQ DX” and now let’s work them!   This comes down to knowing what which bands to use when, what type antenna for making the contact, and being persistent.

1) Understand and use the gray line effects and the layers to your advantage.  See http://www.astrosurf.com/luxorion/qsl-propa5.htm for information.

2) Get the timing down of throwing out your call if there is a pile up by listening to the DX station's rhythm and pattern of working the calls.

3) Be sure your transmitted audio is as clean as possible with no RF on it, and that it is well articulated and not overdriven.  For DX you want to roll off the low end.  A range of 200-2800 Hz is a good starting point for DX audio, then add a little compression, but not a lot, as this can distort and muddy up your audio.   Add a little emphasis to your mid and high section.  If you can run some leveling to keep your audio at a fairly consistent level that can also help.  If you have an option to run some type of expander or noise gate which can help get rid of, or lower background noise do so.  The point here is, if you have good clean easy to understand audio you’re more likely to get the attention and return to your call from the DX station.

4) Stick with it and don’t give up or become frustrated because the station didn’t answer your first, second, third, or fourth calls.  Band conditions on his end are different and he is hearing stations from different locations, and sometimes propagation is better between certain areas resulting in stronger signals to him.  The important thing is keep trying and toss out your call between the other stations calling him.  Also if he is working split frequencies, listen around in the range of split he is working.  Having a rig that allows receiving two different frequencies at once can be a big help.  Tune around the split area when others are calling and try to find a spot with less congestion.  See if he has a pattern... you’d be surprised by how many do!

5) Another option, if available, is a band scope.  One of the big reasons I like the rig I am running is because not only can I hear both the DX station and those calling it when working split, but I can easily “see” where others are and where to set my TX frequency at to avoid being buried under the barrage of calls from other stations which makes it hard for the DX station to pick out a call sign to reply to.  If I’m in a less crowded area in his split range I stand a better chance of working him. It is also useful for watching a large section of the band and performing a “hunt and pounce” method to work them.

6) Use a DX spotting cluster.  There are many free options available on the internet via either a software install or website based.  Look at the postings of DX stations and pay particular attention to those stations who spotted them... are the spotters near you?  This might be an indication that the DX station has good propagation and signals from your area.

Lastly, for those of you who think the bands are “dead”, that you need a “big gun” station to work what DX is there, and think I’m just full of hot air, please feel free to check my log which is available on QRZ and my website: http://kd8lcd.com/

So, are the bands really “dead” or is it a lack of a proper setup and operating style?  Don’t fall victim to the opinions of those who are not using the right equipment and proper operating techniques, causing you to miss some good DX or worse yet a rare contact.  Hang in there, stay with it and be persistent, and in the end you’ll be the one who understands propagation and what to use and when, especially in an emergency situation.  Think about this: If these guys think the “bands are dead” and have a hard time making a contact now, how are they going to be the ones helping with communications should a disaster occur?

Rick KD8LCD
September 2, 2012

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