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Many thanks to Dennis Walter at Bonito for sharing the following product announcement:
MegaDipole MD300DX wideband active dipole
The MegaDipole 300DX is a broadband active dipole with a maximum upper working frequency of 300 MHz. The dipole reacts to the electrical component (E-Field) of the electromagnetic field and will deliver best results regarding signal strength and SNR (signal -to-noise-ratio) at locations with little or no locally generated interference. Nonetheless, the receiver to be coupled to this antenna should have a high enough dynamic range so that it can effectively process the received signals.
In contrast to simple E-field antennas with only one radiating element, the symmetrical construction of the MegaDipole 300DX, will result in almost no negative resonance effects or reflections caused by the coaxial cable.
First choice for DXer
The MegaDipol MD300DX is the ideal antenna for DXers. Particularly in electrically quiet environments, it can really play to its strength in efficiently amplifying weak signals. In practical operations, a maximum signal-to-noise ratio of 110dB was achieved! (see image )
Wideband
With prodigious broadband capability and constant receive characteristics the MegaDipol MD300DX is ideal for wideband receivers, SDR’s and WEB-SDR such as KiwiSDR etc. The MegaDipol MD300DX can of course also be operated on all other receivers, including lower-end SDRs and portable world receivers.
Dual Power Power Supply
The MegaDipol is nominally supplied with 10 – 15V DC (max 40mA), however, it can be operated across a wide variety of supply voltages. The antenna can even be operated with slightly reduced IP values at the same gain with only 5 volts via USB. This offers a significant advantage in that you can supply the MegaDipol on trips away from the radio shack or DX expeditions autonomously, using a low-noise USB power-bank.
The MegaDipol has already attracted a lot of attention with its receive performance at various events such as DX-Camps, field days and in-house exhibitions. In these tests, the MD300DX surpassed the existing antennas usually by 10-15dB in the SNR.
Technical data
Frequency range: 9kHz – 300MHz
IP3: typ. +30dBm (@7.00 & 7.20MHz)
IP2: typ. +78dBm (@7.00 & 7.20MHz)
Size/weight: 98 x 90 x 38mm / 0.12kg
Whats in th Box?
MegaDipol MD300DX
Power Inserter CPI 1000DP
2x 2.5m long radiating elements (PVC-coated, salt-water resistant stainless steel ropes)
2 insulators for installation (weatherproof plastic material with 4.5mm fixing hole)
Many thanks to SWLing Post contributor, Bill Hemphill (WD9EQD) who shares the following:
I went to the Warminster Amateur Radio Club (WARC) hamfest [yesterday] in Bucks County, PA. For some time, I have been thinking about making a loop antenna for AM DXing. It was my lucky day. When I walked to the inside tables, on the very first table was this homemade loop antenna gentleman was selling from an estate.
I snatched it up for $40.
Attached are some photos of it. It’s 25” by 25”, with a swivel base. There are 23 turns of wire and I have no idea what size the capacitor is. I did some preliminary tests and it tunes from 280 kHz to 880 kHz. So it’s the covers the high half of the long wave band and the low half of the AM band.
It’s very well made and I fugue I can modify it to cover the entire AM band.
[…]I hooked the SDRplay RSP2 to it and was getting good signals of major stations all the way to 15 mHz.
That’s with it sitting on my dining room table. Of course the capacitor wouldn’t peak the signals.
So it was a great day at the hamfest!
Indeed that was a great find, Bill! Someone spent a decent amount of time building that furniture-grade loop support. Indeed, it’s very reminiscent of 1920s-30s mediumwave loops!
What I love about your loop (and that of Thomas Cholakov) is that one can see how simple these antennas actually are to build. The only complicated bit is the support, but even that’s simple if you use the shield of a heavy coax or flexible copper tubing.
Thanks for sharing and enjoy logging DX with your new-to-you loop!
Checking out transoceanic DX propagation at an exotic ocean beach site can provide the hobby thrill of a lifetime– if a DXer is lucky enough to choose the ideal time, place and gear to make the chase. All of these fell into place in an amazing way during a 5-day trip to Aitutaki Island (2600 miles due south of Hawaii) with Ultralight radio gear, resulting in the reception of MW stations in India, Bangladesh, Mongolia and Cambodia– all at over 6,800 miles.
Because of extensive QRM from Australia and New Zealand the total number of Asian stations received was limited, but it was definitely a case of quality over quantity. Phenomenal gray line propagation around sunrise shut down Japanese signals almost completely, but boosted up those from the exotic countries in east and south Asia. Korean station reception was limited to the big guns, which was also primarily true for Chinese signals. Except for the ANZ pest QRM, the conditions seemed custom-designed for a west coast DXer to go after the exotic stations which rarely– if ever– show up in BC, Washington or Oregon (even though the Cook Islands’ distance to them is greater).
7.5 inch loopstick C.Crane Skywave SSB Ultralight
Ocean beach propagation at sunrise was strong enough to bring in both 693-Bangladesh and 1431-Mongolia at S9 levels almost every morning on my Ultralight gear, and allow both 657-AIR and 918-Cambodia to break through ANZ QRM on April 12th. No doubt many more of these exotic stations could have been logged except for Australian QRM on 576, 594, 872, 883 and 1566, but this only added to the thrill of the chase. The overall results were exceptional for a DXer using only a 7.5 inch loopstick Ultralight radio and 5 inch “Frequent Flyer” FSL– all designed to fit within hand-carry luggage, and easily pass through airport security inspections. Thanks very much to Alokesh Gupta, Hiroyuki Okamura, Jari Lehtinen, Chuck Hutton and Bruce Portzer, who all assisted in the identification of these stations!
657 All India Radio Kolkata, India, 200 kW (8,075 miles/ 12,995 km) Recorded by accident during a sunrise check of the Korean big guns at 1641 on April 12, reception of this longest-distance station went unnoticed until file review after return to the States. The female speaker (in the Bengali language) is the third station in the recording, after the female vocal music from Pyongyang BS and the Irish-accented male preacher from NZ’s Star network. Her speech peaks around 40 to 50 seconds into the recording. The isolation of the Star network at the 55 second point was done by the Ultralight’s loopstick, not by the propagation. Thanks to Alokesh Gupta for the language and station identification:
657 Pyongyang BS Pyongyang, N. Korea, 1500 kW Like most east Asian signals the N.K. big gun sounded pretty anemic in the Cook Islands. Its female vocal music at 1641 on April 12th shared the frequency with NZ’s Star network (Irish-accented preacher) and AIR’s female Bengali speaker:
693 Bangladesh Betar Dhaka, Bangladesh, 1000 kW (7,960 miles/ 12,810 km) Probably the biggest surprise of the DXpedition, with S9 signal peaks on 4 out of 5 sunrise sessions. Frequently snarling with the Oz pest 3AW, it usually managed a few minutes on top of the frequency each morning from 1630-1700 UTC. Exotic South Asian music was the usual format, and was very easy to distinguish from the talk-oriented format of 3AW (and other Oz co-channels). This first appearance at 1652 on 4-10 featured a “Bangladesh Betar” ID by a male speaker at 8 seconds into the recording (thanks to Chuck Hutton for listening):
774 JOUB Akita, Japan, 500 kW Oddly enough, this was the only Japanese signal making it to the island during the entire trip. Mixing with a goofy-sounding 3LO announcer at 1613 on 4-11, the Japanese female speech concerns a “doobutsuen” (a “zoo” in Japanese, similar to what the frequency sounded like with the 3LO announcer):
819 KCBS Pyongyang, N. Korea, 500 kW The N.K. big gun managed a potent signal for its 3+1 pips across its “TOH” at 1630 on 4-12 but never could shake off RNZ’s Tauranga transmitter:
909 CNR6 Quanzhou, China, 300 kW Strong signal with CNR ID (1:08) and Mandarin speech by male and female announcers. NZ’s Star network was apparently off the air at the time, since it was a real blaster when transmitting:
918 RNK Phnom Penh, Cambodia, 600 kW (6823 miles/ 10,981 km) Breaking through the Shandong and Oz QRM at an ideal time to dominate the frequency, its sign off transmission with the National Anthem peaked just before the 1700 TOH on April 12. Female speech in the Khmer language and exotic music are featured just before the anthem (thanks to Hiroyuki Okamura and Jari Lehtinen for listening, and identifying the National Anthem):
918 Shandong RGD Synchros (Multiple) The dominant Asian signal on the frequency, it rarely allowed Cambodia to sneak through. Here it is with female Mandarin speech at 1647 on 4-11:
Shandong RGD’s transmitters were poorly synchronized, resulting in the two-tone time pips at the 1700 TOH on 4-12 (during Cambodia’s National Anthem at 1:40, in the MP3 linked below). Although actually from two different transmitters, the sound effect sounds similar to that of a “cuckoo clock,” resulting in some initial confusion about their source:
972 HLCA Dangjin, S. Korea, 1500 kW The South Korean big gun played the part on most mornings, including this S9+ Korean female speech at 1631 on 4-12:
981 CNR1 Synchros Changchun/ Nanchang, China, 200 kW/ 200 kW The first of three CNR1 frequencies which usually produced strong signals, this music // 1377 was received at 1624 on 4-12:
1377 CNR1 Synchros (Various) Overall this was not only the strongest Chinese frequency on the band, but was the strongest Asian station on the band as well. Awesome S9+ signals were typical each morning, as with this male speech and music at 1622 on 4-12:
1431 Mongolia (Relay Station) Choibalsan, Mongolia, 500 kW This station was easy to receive on the first attempt, with very little competition on the frequency. It typically managed an S9 signal after 1630 daily with the BBC’s Korean service, which seemed to be broadcast during the peak sunrise enhancement time in Aitutaki’s ocean-boosted propagation. Here is BBC’s Korean male announcer at an S9 level at 1632 on 4-11, with the BBC interval signal at 47 seconds into the recording:
1566 HLAZ Jeju, S. Korea, 250 kW A very poor signal was typical during this trip, with the Chinese service barely showing up under 3NE and two other DU English stations (probably 4GM and Norfolk Island). Whenever 3NE was in a fade it had a chance, since other two co-channels were running very low power. Here is the latter situation, with the weak Chinese barely audible under the DU English snarl at 1641 on 4-12:
1593 CNR1 Changzhou, China, 600 kW This was another Chinese blaster, with S9 signals typical every morning. Here it was at 1641 on 4-12 with male Chinese speech and music at 1377:
Amazing, Gary! Thank you for taking us along on your excellent Ultralight DXpedition. With a modest portable radio and a little antenna ingenuity, you’re enjoying some outstanding DX! You’re living proof of the point I was trying to make in a post yesterday!
Thomas: I know you’re a self-proclaimed pack geek and so am I! You published a photo of your EDC pouch in a post last year. Just a teaser really! What is that pouch and I assume you have a larger carry bag as well? Can you provide more details? I’m ever revising and honing my own EDC pack. Any details would be appreciated.
Thanks for your question Matt! Besides radio, you’re bringing up on one of my favorite topics: packs! You may regret having asked me!
Yesterday evening, I snapped a few photos of my EDC (Everyday Carry) bag and the pouch you’re referring to. Your inquiry is prompting me to consider publishing a more detailed look at my EDC gear–especially since radio is such an important part of it.
I do carry a larger EDC bag at all times. Typically, this is the Tom Bihn Pilot:
For years, I carried a Timbuk2 messenger bag, but it didn’t have the type of organization I prefer in an EDC bag. My EDC bag must be rugged, water resistant and accommodate my 13″ MacBook Air while still having enough depth to comfortably fit the rest of my gear.
I’ve been using the Tom Bihn Pilot for almost a year and have been very pleased. The Pilot is an investment to be sure, but (like Red Oxx) Tom Bihn construction quality is superb and comes with a lifetime warranty.
It’s amazing how much gear will comfortably fit inside without making the bag bulge. The Pilot also has a dedicated water bottle pocket in the middle of the front panel. While I do carry water, it primarily houses my never-leave-home-without-it Zojirushi Stainless Steel Mug (affiliate link) which is filled with piping hot dark roasted coffee!
I also use the water bottle pocket to hold full-sized handled VHF/UHF radios. It accommodates either my Kenwood TH-F6, Yaesu FT2D, or Anytone AT-D868UV perfectly. Indeed, all of the front pockets will accommodate an HT since the zippers terminate at the top of the bag. Long antennas can easily poke out while the zipper still seals 99% of the opening.
The Pilot has one main compartment that houses my 13″ MacBook Air laptop.
The Pilot laptop compartment is spacious and has two built-in pockets opposite the laptop sleeve: one of these pockets (the one on the right in the photo above) holds my EDC pouch, the other holds first aid supplies, an Olight SR1 flashlight and Nitecore LA10 latern (affiliate link). My laptop is in a TSA-friendly Tom Bihn Cache.
Everything has its place. Not only does it hold my Yaesu VX-3R handheld, but also a multi-function knife, a Leatherman Style PS tool, clippers, earphones, multi-bit screwdriver, USB stick, notepad, spare VX-3R battery, a mini first aid kit, titanium spork, and much more! Someday I’ll pull the whole thing apart and note each item.
Why do I choose the Yaesu VX-3R? First of all, it’s compact. This HT is so small it’ll tuck away anywhere. Not only is it dual band, but it’ll also receive the AM broadcast band (even has a little ferrite bar inside), the shortwave bands, and the FM broadcast band.
The mini rubber duck antenna will work in a pinch, but I also carry a flexible Diamond SRH77CA in the floor of the Tom Bihn Pilot’s main compartment.
When I attach the Diamond antenna, it significantly increases the VX-3R’s capabilities.
While the VX-3R does cover the HF bands, don’t expect amazing performance. Selectivity is poor, but sensitivity is adequate. For a shortwave antenna, I carry a short length of coax: one end is terminated with an SMA connector, the other has the center conductor exposed.
I also carry a short alligator clip cable which I clip to the exposed center conductor and then to a length of wire. The end result is a very cheap, flexible and effective portable HF antenna!
Someday, I’ll take everything out of my EDC pack, inventory the contents and publish a post about it. Somehow, that’ll please my inner pack geek! I’m overdue a review of the Tom Bihn PIlot and Synapse 25.
Post readers: Do you have an EDC pack built around a radio? Please comment and include links to your favorite gear!
Many thanks to SWLing Post contributor, Gary DeBock, who shares the following note about his recent Cook Island DXpedition:
The farthest DX received during the Cook Island DXpedition (on Aitutaki island) was 657-All India Radio in Kolkata, India, at 8,072 miles (12,991 km). Recorded by accident during a sunrise check of the Korean big guns at 1641 on April 12, reception of this longest-distance station went unnoticed until file review after return to the States.
The female speaker (in the Bengali language) is the third station in the recording, after the female vocal music from Pyongyang BS and the Irish-accented male preacher from NZ’s Star network. Her speech peaks around 40 to 50 seconds into the recording.
The isolation of the Star network at the 55 second point was done by the Ultralight’s loopstick, not by the propagation. Thanks to Alokesh Gupta for the language and station identification!
Many thanks to SWLing Post contributor, Thomas Cholakov (N1SPY), who shares his latest video explaining the operation of a simple homebrew AM loop antenna:
Brilliant video, Thomas! I love the fact you included a demonstration with your SDRplay RSP1A as well. Via the spectrum display, it’s easy to see the the loop’s bandwidth and also the gain it provides when tuned to a station.
I love your AM loop antenna as well–such a simple design and ideal for demonstrating the mechanics of a passive loop antenna since all of the components are visible. I’m willing to bet you built this antenna for less than $10. Smart design as it’s both portable and effective! Keep up the excellent work, Thomas! We look forward to all of your future videos.
Many thanks to SWLing Post contributor, The Professor, who shares the following review of the RFA200 external ferrite antenna:
The Tecsun R-9012 and RFA200 MW antenna (Photo credit: The Professor)
A Quick Review of the RFA200
The Professor
I’ve considered saying something here about RFA200, as I bought one of these not long after its existence was announced on this blog a few months ago, but I’ve been hesitating because I didn’t have much good to say about it. A couple of times I’ve placed it up snug up against the the top of the two Tecsun sets I have handy (the PL-310ET and the PL-880) and found that despite a lot of knob turning it had little or no effect on improving signal on medium wave stations. I was not impressed.
But I guess I’ve kind of changed my mind on that. And oh yeah, I bought another radio. It’s funny how you can talk yourself into things when you’re talking someone else into something. But after I had mentioned to a reader here the other day that the very inexpensive Tecsun R-9012 was a worthy analog DX portable, I decided to drop twenty and pick one up for myself. After all, it was about the same price as a fancy Brooklyn hamburger. It arrived a couple days ago.
So, I have been playing with it a bit over the last few days. It’s as good as the other ones I’ve had which are the same basic radio (I’d mentioned that the bandswitch slider broke in a couple of mine). It’s single conversion. The bandwidth is a little wide, but it’s a very sensitive and simple analog set.
Yesterday I was going through the AM band and remembered that ferrite from Greece, and I pulled it out recalling that in my experience some radios are more susceptible to reception improvements using passive loops than others. Maybe this ferrite bar might be similar. And sure enough, the antenna made a notable difference this time. By placing it up against the R-9012 and tuning the thing I could certainly increase signal a bit. And I could even see it in the slight brightening or steadiness of the tuning light.
So, not a total waste money after all. I would emphasize that the difference in reception doesn’t seem to be as dramatic or sustaining as you might hear with a tunable loop antenna next to your radio. But it’s not junk either. Then again, for fifty dollars shipped it is a little pricey. Twice as much as a Tecsun tunable loop antenna, and two and half times more expensive than the R-9012 itself.
I found the best way to use this antenna is to tune the radio separately first and when you find a weaker signal you want to improve physically go ahead and rotate the radio until the signal is strongest and THEN put the antenna along the top of the radio and adjust the tuning knob on the antenna. Focus in on strengthening the signal you actually hear, going back and forth until it gets strongest. If you seem to be pulling up other stations it’s because the antenna adjustment will bring in adjacent stronger stations if you move it too far either way.
I’m surely not able to pin down the science involved in exactly how these things work, but perhaps somebody can chime in on this. I’m wondering if analog radio tuning in particular is better suited to the use of these tunable passive antennas, as opposed to PLL and DSP radios?
If you buy one of these be prepared to wait. At least mine took weeks to get here from Greece. And don’t expect miracles. But it seems rather well constructed, and will probably work with some radios. The seller has a 100% rating on eBay and has all sorts of interesting antennas for sale. I’m glad to see people succeeding in that business.
Many thanks, Prof, for sharing your fine review of the RFA200! Thanks for also mentioning the Tecsun R9012–I purchased one a couple years ago with the intention of reviewing it, then gave it to teenager who expressed interest in shortwave. I don’t think I actually put it on the air myself. I do enjoy simple old school analog radio–especially when making band scans.
