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Many thanks to SWLing Post contributor, Giuseppe Morlè, who writes:
Dear Thomas,
This is Giuseppe Morlè again. First of all, Happy New Year to you and to the whole SWLing Post community! I’ve been continuing the tests on my “T Ferrite” antenna for medium wave and the 160 meters ham meter band.
I tried the antenna inside my shack listening to Rai Radio 1 from Milan Siziano, about 800 km from me, on 900 kHz in the early morning after sunrise. The antenna, despite being inside, proved to be perfect for the cancellation of the electrical noise that I had around me.
Disconnecting the antenna from the receiver–a Sangean ATS-909–the noise occupied everything without being able to listen to anything. Putting the antenna back, the noise disappeared completely making the modulation re-emerge, with a weak signal, it was already day, but with good understandability.
The antenna, as I described in another article, is composed of 2 ferrites 12 cm long each, bought at ham fests, tied together with insulating tape.
For the two windings, I used a small section of cable used for telephone systems that is rigid enough to model perfectly on the ferrites–43 turns for the primary and 3 turns for the coupling link to the receiver. The variable capacitor is 850 pf.
I should mention that the magnificent W1VLF channel was my original source of inspiration for this antenna.
That is amazing, Giuseppe! We often think of magnetic loops as the only choice for coping with urban noise and RFI, but ferrite bars–especially configured like yours–are a brilliant tool for indoor low-band listening. Thank you for sharing! We love your experiments.
Many thanks to SWLing Post contributor, Mike, who writes with the following question:
How important is AM Sync for a portable radio? Is it essential or a deal breaker?
That’s a great question, Mike, and one I don’t think I’ve directly addressed it here on the SWLing Post oddly enough.
Synchronous detection is actually a fairly deep topic to explore–and everyone has their own opinion–but I get the impression that you’d like a simple answer, so I’ll try to keep this as brief as possible. You might follow the comments section of this post as I’m sure some SWLing Post readers will share their thoughts on synchronous detection and how important it is for them.
In electronics, a synchronous detector is a device that recovers information from a modulated signal by mixing the signal with a replica of the un-modulated carrier. This can be locally generated at the receiver using a phase-locked loop or other techniques. Synchronous detection preserves any phase information originally present in the modulating signal. Synchronous detection is a necessary component of any analog color television receiver, where it allows recovery of the phase information that conveys hue. Synchronous detectors are also found in some shortwave radio receivers used for audio signals, where they provide better performance on signals that may be affected by fading. To recover baseband signal the synchronous detection technique is used.
How does synchronous detection help shortwave, mediumwave, and longwave listeners?
As the Wikipedia article notes above, sync detection can help “provide better performance on signals that may be affected by fading.”
In short: a solid synchronous detector can help stabilize an AM signal which then can help with overall signal intelligibility.
In some modern portable radios, at least, this could come at the expense of audio fidelity (see caveat below).
I use sync detection when the bands are rough, noisy, and QSB (fading) is affecting signals.
A good sync detector will help clean-up and stabilize the signal so that you can hear voice information with less listener fatigue. Sync detectors are also great tools for grabbing station IDs when propagation is less stable. If you have a receiver with selectable sideband synchronous detection, it can also be used as a tool for eliminating adjacent signal interference.
Caveat? Sync detectors vary in terms of quality.
The PL-880 has a synchronous detection “hidden” function. I’m sure it’s hidden because it’s so ineffective. The PL-880 is a fantastic portable, but don’t bother using the sync detector.
Many modern DSP portables sport synchronous detection, but they’re not terribly stable and the audio fidelity can take a big hit as well. Poor sync detectors can make audio sound “tinny” and narrow.
If a sync detector isn’t effective a providing a stable lock on a signal, then it’s pretty much useless. Why? If it can’t maintain a stable lock, it’ll produce very unstable shifting audio, often with the occasional heterodyne sound popping in as well. In those cases, it’s better to turn off synchronous detection.
Benchmark legacy tabletop receivers and modern Software Defined Radios (SDRs) typically have solid, effective sync detectors. Indeed, I rarely have the AM synchronous detector disengaged on my WinRadio Excalibur–that particular SDR and application enhance audio fidelity through sync detection.
I find that I use sync detection less with my Airspy HF+ Discovery and SDRplay RSPdx, for example, because the OEM applications natively does a brilliant job managing unstable signals.
In terms of portables, I’ve always considered the sync detector of the Sony ICF-2010, Sony ICF-SW7600GR, and PL-660/PL-680 to be pretty solid. I’m sure readers can suggest even more models.
Is sync detection an essential feature on a portable radio?
Not for me. But I do admit that I value the radios I own that sport a good sync detector.
For some SWLs and DXers, however? It might very well be a deal-breaker if a radio doesn’t have a sync detector, or if its sync detector doesn’t function well.
What do you think?
Is the lack of sync detection a deal-breaker for you? When do you employ sync? Please comment!
I’m Giuseppe Morlè (IZ0GZW) from Formia, on the Tyrrhenian Sea, in Italy .
I built this simple rotating directive ferrite antenna for medium waves and the 160 meters ham band.
Inside the tube there are 2 ferrites with 43 cable windings and 3 for the coupling link that goes to the receiver.
In this video the test as soon as I assembled everything …
In broad daylight, it was 12.00 local time, you could hear well over 2000 km.
The antenna is very directive and perfectly manages to separate several stations on a single frequency.
The pipes are in plastic for plumbing use (PVC), I bought only that one, 5 Euros, the rest is all recycled.
I wanted to share this simple and very functional project of mine with the SWLing Post community.
Thanks and I wish everyone a better year.
Greetings from Italy.
Giuseppe iz0gzw.
Thank you, Giuseppe! What a simple, effective antenna project. I like how you’ve invested so little and recycled parts from other projects. I also love your view there looking south over the Tyrrhenian Sea! What a great place for radio.
Many thanks to SWLing Post contributor, Sorin, who writes:
Hello Thomas,
I’ve read with interest your blog and inputs about the XHDATA radio.
Now since yesterday I own such a radio, and I’ve noticed it has aspects that are superbly resolved, but I miss a complete Instruction Manual. The pdf you have there (the same as the printed one that came with my radio) isn’t describing some matters, I will highlight just those I’ve confronted:
– How do you set the local time? The manual stops at saying how to switch from Automatic (I guess from the unreliable RDS clock) to Manual. What buttons are to be pressed further to set the time ?
– How do you save radio stations beyond the 10 pcs on Page 00? Ho do you go further from Page 00 to some other ? Pressing further the Page button doesn’t change anything.
– How do you call saved stations from other pages that Page 00?
best regards,
Sorin
Thank you for your question, Sorin. I’m letting a friend borrow my D-808 so, unfortunately, don’t have it handy to confirm this for you. My hope is that an SWLing Post reader can help.
Please comment if you can help Sorin with these D-808 functions!
Many thanks to SWLing Post contributor, Justin (N2UJZ), who shares the following Icom IC-7300 tip:
I was looking for a way to completely disable the TX (to share an antenna) on a IC-7300 and found this article. I didn’t get any answers saying “yes” but I just figured it out and yes it can be done.
Press ‘Menu”, then press “Set”, then “Function” to bring up a menu starting with “Beep Level.” The fourth item down is “Band Edge Beep.” You want to set that to “ON (User) & TX Limit”
Then once that is turned on, there will be a “User Band Edge” option in the Function menu. Under that select and delete all of the band edges. The radio will now not TX at all from any button on any band. To re-enable TX, change the “Band Edge Beep’ anything other than TX Limit.
[IMPORTANT] Don’t forget to save to the SD card before deleting the band edges or you might have to re-enter them.
I was just disconnecting the mic until today but this way I’m a little more at ease now with the 7300 sharing an antenna with the HackRF. 73, Justin N2UJZ.
What a brilliant tip, Justin. Thank you for sharing this!
Many thanks to SWLing Post contributor, Joe Patti (KD2QBK), who writes:
Not sure anyone would be interested, but in using a Bluetooth adapter with my Belka I inadvertently came up with a little stand for it.
I attached the adapter to the back of the radio with a piece of plastic 3M Command picture hanger strip. It props up the little radio at exactly the right angle.
Love the blog!
Thank you, Joe! Looks like this is the Bluetooth adapter you’re using. What a clever way to have your Bluetooth adapter do double duty! Also, I’m so glad you enjoy the Post! Thanks for sharing your tip!
Many thanks to SWLing Post contributor, TomL, who shares the following guest post:
My First Loop-On-Ground antenna
A number of people have mentioned the Loop On Ground (LOG) antenna in the past as a good receive-only antenna. I did some research but could only find a few examples by amateur radio operators.
Matt Roberts (KK5JY) has a good article including some antenna theory and measurements, you can find it here:
I also read somewhere that for transmitting, a LOG antenna is useless as it radiates much of the energy right into the ground! But I didn’t care about that. I needed something for receive I can deploy easily without supports and take down just as easily. As you may recall, my home condo is literally saturated with noise and I cannot null it out. So a wire looped on the ground is supposed to work? You bet it does!
Of course, there are some conditions to meet. There has to be enough flat ground away from people or pets (or lawn mowers!) who would get tangled in the wire on the ground. The wire should be as close to the ground as possible (although I had good results laying the wire on top of cut grass). The loop of wire can vary in circumference from about 20 feet to 150 feet (the shorter length will stay in an omnidirectional pattern higher in frequency but lower in signal pickup and vice-versa for the longer length). The wire needs to be insulated. That’s about it!
So, off to the hardware store to buy a cheap spool of 100 foot 18 gauge speaker wire. But, the articles mention using a balun and they all made their own. I did not feel like doing that (I am not that good at making things from scratch) and I did not want to spend money ordering one. More reading somewhere informed me that my existing Wellbrook Medium Aperture loop amplifier has a built-in balun at the antenna side of the device. Hallelujah!
I bundled together the wire, Wellbrook parts and battery supply, small laptop and Airspy HF+ to my favorite Lake Nelson Forest Preserve. The shelter there is little used and is adjacent to the prairie with cut grass. It did take a good 15 minutes to lay out the 100 feet of wire on the ground while trying to keep it as flat as possible. And I did not have enough space for a circle, so I ended up with an oblong shape. The long sides are facing directly north-south, so in theory (I think) this gives me an oblong shaped reception pattern east-west. The photo shows half of the wire laying on the grass.
I ended up with this setup on a picnic table at the rear end of the shelter. The coax wire goes from the Wellbrook amp into its power module, then to a Cross Country Wireless preselector, then to the Apirspy HF+ and laptop.
I was really impressed by the signal strength of the usual suspects like Radio Nacional da Amazonia. I could see that the Wellbrook amp was boosting signals across the board with only a little extra noise.
I use the preselector to try to keep the Airspy radio from overloading, especially mediumwave broadcast signals which can sound like a small amount of extra “hash” type noise in the background. I have since added into the accessory chain an old Kiwa Electronics BCB filter that does a great job of knocking down the frequencies below 2 MHz.
I have also since added a water resistant box to enclose the Wellbrook amp to keep it safe from getting stepped on or too wet.
Also, a couple of weeks later I was able to go to a campgound and try out 60 feet of wire but the result was noisier since I was surrounded by RV vehicles in a crowded campsite. It was not horrible and I was able to listen to some good radio stations but location can matter with any antenna.
I hope you like the recordings below. Because of some serious health issues this summer, these May 31 2020 recordings & report are just being published now (I am recovering slowly but surely!). My small laptop is under-powered, so I was only able to record MP3 files one at a time. It kept me busy as I went from one frequency to the next and kept recording anything I heard. I was able to hear a couple of stations I never heard before and that is a success in my book.
It remains to be seen if this antenna is as good as my 19 foot vertical antenna attached to the top of the car roof, especially low-angle DX signals. Maybe you will have the chance to experiment as well and share your experience, too. Now, will a small loop-on-ground antenna around my car parked late at night at a far corner of the grocery store work OK??? I will have to try it!
Recordings (crank up the volume if it is too weak):
22:00 UTC, Radio Saudi (Arabic) 11915 kHz
22:04 UTC, KDSA Adventist Radio (Indonesian) 11955 kHz
22:14 UTC, KDSA Adventist Radio (English) 12040 kHz
22:20 UTC, Voice of Korea (Japanese) 11865 kHz
22:23 UTC, Yemen Radio (heavily jammed) 11860 kHz
22:35 UTC, Radio Brazil Central (Portuguese) 11815 kHz
22:50 UTC, WWV booming in 10000 kHz
23:11 UTC, UnKnown (might be FEBC) 9795 kHz
23:15 UTC, China Radio Int’l (Spanish teaching Chinese, from Kashi) 9800 kHz
23:17 UTC, China Radio Int’l Business Radio (from Xianyang) 9820 kHz
23:19 UTC, China Radio Int’l (Chinese from Urumqi) 9865 kHz
23:21 UTC, Voice of Korea (Korean) 9875 kHz
23:23 UTC, Maybe Radio Taiwan without jamming from CNR 9900 kHz
23:34 UTC, China Radio Int’l (Chinese from Bamako Mali) 7295 kHz
23:43 UTC, Radio Nacional da Amazonia 6180 kHz (& 11780 kHz around 40 seconds)
23:50 UTC, MAYBE China PBS from Xinjiang in Kazakh (nothing else listed on schedules) 6015 kHz
23:56 UTC, Radio Mali (French announcer humming to music and acting crazy) 5995 kHz
00:30 UTC, XEPPM Radio Educacion (Spanish Mexico City) 6185 kHz
This is brilliant Tom! Thank you for sharing.
Our antenna guru contributor, Grayhat, has been encouraging me (understatement!) to build a Loop-On-Ground antenna but I haven’t done this yet because, at home, our driveway would interfere with its deployment. That and I have no RFI to speak of in my rural/remote home so my skyloop antenna is tough to beat. But having one available for portable use would make a lot of sense. I’m going to put this on my 2021 project list!
Post Readers: Do you use a LoG antenna at home or in the field? Please comment!
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