Category Archive: SWL

SWL is “short-wave listening”. In my case I am listening to other ham radio operators far more than International Short-wave Broadcast Stations

Better Listening using Lower RF gain

BETTER LISTENING THROUGH LOWER RF GAIN!

 
Cute picture of little girl wearing headphones
 

I guess I shouldn’t be surprised. I’ve read about turning down the RF gain when two or more signals are coming in at nearly the same frequency. It basically serves to mimic an improvement in selectivity. However, since entering the ham world during the lowest solar cycle slump of the last 100 years, most often finding even one signal to listen to has been the greater challenge. I should be so lucky as to find two signals competing for my attention. So it wasn’t that situation that led me to discover that turning down the r-f gain can
sometimes improve the intelligibility of the voices I was listening to, even when no other signal was crowding in.

Recently, I have been hearing more hams on the air than I did in 2009. I attribute some of that to getting my ICOM 730 tuned up, but most of all I think it is due to there being more
days with good conditions for radio-wave propagation. It has been very noticeable that only once in a while there is a day when I am picking up signals all across the 20m band for several hours in the middle of the day and sometimes right into the evening. But I’ve also noticed that I seem to having a lot more days when there is seriously higher noise level, sometimes across the entire 20m band. The higher noise days don’t seem to follow any pattern relative to the good receptions days. Sometimes they cross paths and sometimes they don’t. Some of the noise may be due to local sources because I have noticed that sometimes it suddenly as if is being turned on with a switch around the dinner hour. And sometimes it has turned on that way around 8 or 9 in the morning. But other times I’ve heard the hams on the air saying the noise level was high for them too, so I think some of the time it’s atmospheric, rather than local sources.

I don’t recall how it happened, but one day recently I suppose the noise level was high and I was listening to a pretty strong signal and I just wanted to knock down that background noise. The noise blanker did nothing, so I slowly turned down the r-f gain and VOILA!
There was a point at which the noise was almost gone while the voice was still loud enough to hear.

Since that day, I’ve done this numerous times. It often improves the clarity of the voice I’m listening to. Since my hearing is not especially good anyway and I don’t usually wear my hearing aids inside the house, anything that clarifies the audio is very helpful for me. Turning down the r-f gain does reduce how well I can hear the 2nd party of the conversation, but quite often I
cannot hear them well enough even at full r-f gain, so it’s not really any loss to shut out what little bit of a scratchy 2nd voice I’m getting.

Little discoveries like this are one of the extra things that make this hobby fun.

I remember the first time I had a radio with a BFO on it way back many years ago. It was probably that Lafayette KT-320 radio that I still have. I discovered I could use that BFO dial to almost make SSB sound like human voices. I’d never had any radio that could render sideband into clear voices. I didn’t know that was one of the things the BFO was for, I was just having a good time playing with the various dials, trying to improve reception and selectivity. That was another one of those enjoyable and almost accidental discoveries.
 


Permanent link to this article: http://w7buf.com/2011/07/28/better_listening/

Bearing Angle / Latitude Mystery!

While looking at the map I made of Ham operators I have heard, I noticed that some of the bearing angles reported by QRZ don’t seem to be what I would expect. For example, I would think that a location East of me, with a SMALLER/LOWER latitude, would show a bearing angle of MORE than 90 degrees. First I noticed that W7WTR in Idaho Falls, showed a bearing angle of 90.0 degrees in QRZ. Then I noticed his latitude is SMALLER/LOWER than mine at 43.545718, compared to my 44.077080. (His longitude is smaller in a Westerly sense, making him East of me; his -112.051715 to my -123.085120, so no problem there). But why isn’t his bearing angle at least a little bit greater than 90.0? His latitude is about half a degree smaller at a distance of 550 miles. Roughly how many miles is half a degree latitude? A ham 100 miles almost due North of me has latitude 45.505. That means that about 100 miles corresponds roughly with 1.4 degrees of latitude. Idaho Falls is 0.52 degrees smaller latitude, so that would translate to about W7WTR being about 33 miles South while 550 miles East. Using trigonometry, I would expect this to be about 3 degrees deviation South of East. On a flat Earth, there is no way that the bearing angle would be 90.0 degrees, it would be about 93 degrees. That suggests that this seeming anomaly has to do with bearing angles measured along “Great Circle” arcs rather than being angles calculated using flat out plane Geometry and Trigonometry.

A second example showed up with WB9Z in Indianna. His latitude is 40.717782, compared to my 44.077080 . He is both East of me and South of me, yet his bearing angle in QRZ is 85.0 degrees, not greater than 90. When I first started thinking about these apparent anomalies, I thought maybe it was because the bearing angle was being measured from MAGNETIC North, instead of from a North South running line of Longitude. So I checked a few locations almost due North and due South of me and they have bearing angles around 3 or 4 degrees from 0 or 180 and therefore seem to be measured relative to a N-S longitude line. In Portland, Oregon, (100 Miles North of me) a compass points 16 degrees east of True North, so if bearing angles were referenced to magnetic North, the “anomalies” I have been talking about would be on the order of 16 degrees, not just a few degrees.

So then, I guess it comes down to Great Circles. A circle made by locations having equal latitude is not a Great Circle – except at the Equator. A Great Circle lies in a plane which has the center of the Earth as the center of the circle. Taking an extreme example, for a location at my latitude but 180 degrees different longitude, i.e.; probably in Russia someplace, the Great Circle connecting these two points would run right across the North Pole. The bearing angle in that case would be 0.00!!! It just will not do, to argue that since this location is neither North nor South of mine according to latitude, the bearing angle should be 90 or 270 degrees. Using the Great Circle mapping capabilities available at   (which is intended for airline flight path estimates),  I got a Great Circle map from my location to a place very very near to WB9Z in Indianna. His bearing angle in QRZ was given as 85.0 degrees, less than 90 even though his latitude is South of mine. In this map, you can easily see that the initial “trajectory” of the Great Circle from my location, is less than 90 degrees. I’m assuming that apparent “trajectory” angle is what is being reported as “bearing angle.” MYSTERY SOLVED!!!!!!

Map showing Great Circle from my location to Indianna

Initial "trajectory" from Oregon is less than 90 degrees on this Great Circle to Indianna



Permanent link to this article: http://w7buf.com/2011/07/22/bearing_angle_mystery/

First Pile-up! July 16, 2011

I’ve heard about pile-ups, but had not run across any until Saturday morning, July 16; around 1430 or 1500 Universal time (7:30 or 8am here on the West coast USA).

Woman Lounging on Sofa listening to a radio with headphones

I was dialing slowly through the 20 meter band and came across a pretty clear voice with an accent I didn’t recognize. This was on frequency 14.197.7MHz. His call ended quickly and right away two other guys tried to call him. He replied to one of them. Again their call was very brief, giving signal reports mostly. This time there were four or five guys trying to call him. I’ve never heard more than two or three people trying to call someone at the same time and even when I’ve heard that it was mostly on Field Day a month ago. I heard the highly-in-demand voice say he was in KOREA! That is 5000 miles away and is the furthest ham I’ve ever picked up. I didn’t get his call sign nor what power or antenna he was using. After his next call, there were more voices than I could count, all at different volume levels and all trying to reach the Korean contact. This is what hams call a “pile-up”. I’ve not heard one before. It was exciting to have been one of the earlier people to hear this Korean ham – before the “pile-up” really got going. It was exciting to hear someone so far away. Up until now, I had picked up Hawaii twice and Japan once and Australia once, though those last two were two years ago when I first got a ham radio and got my operator’s license.

Some of the guys I heard very clearly calling the Korean ham, were: K1QS from Maine – 2500 miles East of here! (He was the greatest distance continental ham I’ve ever picked up. He did manage to connect with Korea – and those two are about 7500 miles apart! Also, I clearly heard AC0O (alpha charley zero oscar) New Mexico at 1100 miles from me. W6KM in San Jose California came in loud and clear; that’s 475 miles. Finally, KY7W from Tempe Arizona, a distance of 950 miles.

Obviously radio propagation conditions were better than I’ve encountered to date. There have been about 3 days in May June and July so far which were pretty good for longer distance radio signals. Two years ago in Spring 2009, when I first started, I had one good day in about three months.

I will admit that I thought about trying to contact Mr Korea. (I’ve never transmitted with my radio yet). I didn’t though because I have not finished working on the quality microphone with amplifier project that I’ve been putting together. At the moment all I have working is the stock hand microphone that comes with the ICOM 730 radio. I’m fussy about audio quality so I am holding back on making my first transmission/contact until I have the better microphone/audio system working.


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Permanent link to this article: http://w7buf.com/2011/07/19/first-pile-up-july-16-2011/

Ham Gal Fussing and Playing

Here is a map showing the locations of ham operators I’ve heard since May 2011

The yellow and purple markers are places/guys heard on my ICOM R-70 RECEIVER.

The pink markers are guys/places I’ve heard on my ICOM 730 TRANSCEIVER since It was given a full tune-up by Mike Alexander at “Affordable Radio Repair.”

CLICK to see full size MAP!Map of Ham locations I've heard


Permanent link to this article: http://w7buf.com/2011/07/17/ham-gal-fussing-and-playing/