{"id":19251,"date":"2016-06-05T06:00:23","date_gmt":"2016-06-05T10:00:23","guid":{"rendered":"http:\/\/swling.com\/blog\/?p=19251"},"modified":"2016-06-05T07:16:25","modified_gmt":"2016-06-05T11:16:25","slug":"guest-post-my-evolving-morphing-sw-listening-station","status":"publish","type":"post","link":"https:\/\/swling.com\/blog\/2016\/06\/guest-post-my-evolving-morphing-sw-listening-station\/","title":{"rendered":"Guest Post: My Evolving, Morphing, SW Listening Station"},"content":{"rendered":"

Many thanks to SWLing Post contributor, TomL, for the following guest post:<\/em><\/p>\n

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\"Sony-2010\"<\/a><\/p>\n

My Evolving, Morphing, SW Listening Station<\/h2>\n

by\u00a0TomL, May 26, 2016<\/strong><\/p>\n

My interest in radio listening has been rekindled after a long hiatus in parallel to my dwindling interest in Mainstream Media.\u00a0 It is now about 8 years without cable TV and I seriously do not miss it, especially with the evolving nature of discovery with respect to other forms of media.\u00a0 SWL radio was important to me in my formative years during the Cold War; fascinating were the many ways governments used shortwave radio to influence populations, each with their own brand of propaganda!\u00a0 Young people today know nothing about the endless (and entertaining) tirades of East German editorial commentaries denouncing the evil, decadent West.\u00a0 Or, of the free, large-sized envelopes full of travel and promotional brochures, pennants, bumper stickers, and booklets sent from the government broadcasters such as Poland, Hungary (yes, communist countries!), Australia, Netherlands, etc. just for sending in one simple QSL report!!!<\/p>\n

I quickly realized that those days are gone forever, consigned to a period of history where radio was THE main method of disseminating copious amounts of government propaganda to very large swaths of humanity.\u00a0 Now, the internet and cable TV fulfill that function in a much more CONTROLLED manner, both technically and socially (Big Brother like).\u00a0 So, I have diversified my interests and have an unusual listening station.\u00a0 It is multiple things in one small space.\u00a0 You see, I live in a very small condo in a noise-plagued environment with only a 2nd<\/span>\u00a0floor wooden deck (owned by the Condo Association!) in which to put up any outside antennas.\u00a0 Only a single \u201cDish\u201d type antenna is allowed.\u00a0 So my shortwave antenna needs to be well hidden.\u00a0 Same for the TV antenna, since I also have a north-facing deck, I cannot have any line-of-sight to the Southern sky for a Dish.<\/p>\n

The first wire antenna strung from the top and brought inside was a dismal failure receiving nothing but noise.\u00a0 I gave up for a couple of years.\u00a0 I built a loop TV antenna and mounted an FM antenna instead since those were less susceptible to noise issues.\u00a0 Also recently added to this station are two cheap 4G antennas with wires into a single Verizon USB aircard plugged into my computer and getting up to 14 mbps performance.<\/p>\n

But, I still wanted to try shortwave radio again (and medium wave too) but the noise issues were very, very discouraging.\u00a0 S9 noise on some bands.\u00a0 Tried preselector, a noise \u201cphaser\u201d, different lengths.\u00a0 Nothing worked.\u00a0 However, I read something from an amateur radio operator in Northern California who had a space problem.\u00a0 He put up a helically-wound-vertical (HWV<\/u><\/em><\/strong>) antenna with radials for 160 meters (John Miller HWV antenna<\/a>).\u00a0 I also read about various \u201cbroomstick\u201d antennas.\u00a0 So, I tried my own version with an old RF Systems Magnetic Longwire Balun I still owned and NO radials.\u00a0 Put it together with a 2 foot long, 4 inch schedule 40 PVC pipe wrapped in 200 feet of 18 awg magnet wire.\u00a0 Well, still noisy but, at least now I had a portable antenna!<\/p>\n

So, I went camping in March of this year!\u00a0 Holy Cow, was it cold out but the helical antenna performed well enough to hear All India Radio for my very first time, a small 1kw Mexican station in the 49 meter band, and various others from Asia that were elusive for me in the distant past.\u00a0 I was finally encouraged again to continue my research.\u00a0 I did this a few more times and finally got tired of going camping just to listen to a radio!\u00a0 NOISE at home was still the big bugaboo to kill (and it still is).<\/p>\n

I read up on Common-mode noise travelling on ground and shield components of antenna systems.\u00a0 So I bought a bunch of toroid ferrites of different types to cover different frequencies (something about initial permeability….) to make my own homemade \u201cSuper RF Choke\u201d to cover all frequencies made on a Home Depot Homer bucket lid, winding the coax 5 or 6 times through all the toroids, the full diameter of the lid.<\/p>\n

Measurements by Jim Brown published on the web (RFI-Ham.pdf<\/a>), pages 32-33) indicate good choke performance using coax with these larger-sized coils.\u00a0 I still hoped to salvage the use of the HWV antenna.\u00a0 So, added the choke and noticed some improvement across most bands (less noise).\u00a0 Medium wave broadcast was not effective and decided that I did not want to keep tuning an antenna that HAD to sit outside to get away from the noise inside my listening station.<\/p>\n

I also shut off the power to my condo and found out which noise sources were mine vs. other noise that came from all the neighbors (very important step to do!!!).\u00a0 For instance, I did not know before that USB charging adapters are PURE RF-NOISE EVIL in an innocently small package?!?!?!\u00a0 I rearranged wiring to shut off certain devices and power strips when I want to listen to the radio!<\/p>\n

So, I kept reading.\u00a0 Found out about another magnetic balun from Palomar.\u00a0 Tried it but not impressed –\u00a0 performance was too lossy compared to the good old RF Systems MLB (what a great product that was back then!).\u00a0 Kept reading and found out good things about the EF-SWL from PAR electronics<\/a> (product is now made and sold by LNR).\u00a0 The ground connections on it (and the Palomar) intrigued me.\u00a0 So, I decided to go to Hamvention for the first time, even though I was skeptical of finding anything useful, I told myself, I could at least buy the EF-SWL on sale (which I did).<\/p>\n

Installed EF-SWL to the HWV but no difference compared to the RF MLB. The antenna did perform better outside on the deck in the far corner, so there it still sits.\u00a0 Then, I hooked up the wire they gave me with the EF-SWL to the ground and it resulted in MORE noise.\u00a0 Then, took off the jumper<\/em> (which connects the coax shield to the ground side of the balun) and connected only the middle post (balun ground) to the ground wire and a lot LESS noise resulted along with a small reduction in radio signal level!!!\u00a0 Finally some progress<\/em> \u2013 the wire seems to be acting like an old-fashioned \u201ccounterpoise\u201d, which is misunderstood these days.\u00a0 Apparently, back in the 1930’s-1950’s, people involved in radio knew the differences between an \u201cearth ground\u201d, a \u201cradial system\u201d, and a \u201ccounterpoise\u201d.\u00a0 Technically, they are all different and their use is different as a result.\u00a0 Now, people moosh all these concepts together interchangeably which risks creating very ineffective antennas.<\/p>\n

\"Photo<\/a>

Photo of installed EF-SWL at the bottom of the HWV with coax at the output, the red magnet wire input on top, the middle post for the counterpoise wire, and the coax shield post is unused.<\/p><\/div>\n

The HWV antenna now has 600 feet of 26 awg teflon wire on the outside PVC, an inside 3 inch PVC \u201csleeve\u201d with 102 Russian ferrite rods, a 56 inch stainless steel whip at the top, and one inch hole through the center to accommodate the 7 foot PVC mount to my carbon fiber photo tripod when I take it camping again.<\/p>\n

So, I am on a new quest to understand counterpoises, how to actually TUNE them and, hopefully, how to use them to increase the performance of shortened antennas like my HWV (something about reducing the dB loss incurred by shortening….).\u00a0 A second result I hope will be how to use the counterpoise to keep signal-to-noise ratio high at the same time<\/em>\u00a0(maybe with this used $100 Dentron Super Tuner bought at Hamvention?).<\/p>\n

\"Transmatch\"<\/a><\/p>\n

Also bought at Hamvention (thanks Thomas W. for the tip!!) and installed Bonito’s Galvanic Antenna Isolator GI300<\/a>.<\/p>\n

If input directly<\/u><\/em><\/strong> to the input of the radio, led to more reduction in noise and signal!!\u00a0 Too much actually, so I took off my Super RF Choke and now I had a better result compared to the EF-SWL with the RF Choke (slightly cleaner sound with less hissy noise).\u00a0 Apparently, the GI300 completely isolates the coax shield, better than my homemade choke!\u00a0 The requirement is to use coax from the feedpoint and not bare wire.\u00a0 I then placed a few clamp-on ferrites I bought from eBay to help with slightly higher frequency choking of the shield at various places on the feedline.<\/p>\n

\"Bonito-Galvanic-Isolator\"<\/a>

Photo of GI300 on radio with NO extra coax lead into the radio at right (Thanks to Dennis Walter of Bonito for that tip)<\/p><\/div>\n

Before Hamvention, I wanted to try out AM broadcast.\u00a0 I wanted to know more about this \u201cFSL\u201d antenna a well-known eccentric from Ireland (Graham Maynard FSL<\/a>) developed before he passed away a few years later.\u00a0 So read up and bought a whole bunch of ferrite rods and tried different configurations.\u00a0 Well, my particular design did not work all that well because I did not follow directions for winding wire into a balanced design.\u00a0 So, I added all those ferrite rods to the 2 foot HWV (inside a 3 inch thin-walled sewer PVC pipe).\u00a0 The antenna is louder down to about 3 MHz with a stronger signal (including noise) than without.\u00a0 I do not have measurements, and find it too time consuming to document.\u00a0 Maybe one day, I will compare and document by sliding the ferrites out on the 3 inch PVC and measure actual signal levels.\u00a0 The ferrite sleeve seemed to pick up MORE noise and radio signal than without it.\u00a0 So, if you need more signal strength in a small package below 7 MHz, then the idea seems to have merit.\u00a0 But since it increased noise as much as radio signals, it has limited usefulness to me.\u00a0 I do have another project where I will put ferrite bars onto a tuned medium wave loop antenna (Tecsun AN100) that is much more portable and directional.\u00a0 The bars and loop were both relatively inexpensive from eBay.\u00a0 The ferrites change the tuning lower, so I have to figure out how to make it tune higher again…….<\/p>\n

\"Photo<\/a>

Photo of unfinished MW loop project.<\/p><\/div>\n

Summary<\/h2>\n

Evolving understanding of dealing with major problems like overwhelming noise and limited space have led to unexpected additions to my SW Listening Station:<\/p>\n