File Attachment 1: 4apr_F_se.mp3
Re: 27th/28th March HiFERs
Ed,
I for one would be interested in a review. I've had that rig in my sights for a while and would appreciate your insights.
John
Reminder: Lowfer net +/- 3927 kHz Saturday morning 0800 California time
Posted by Jerry Parker on April 02, 2021 at 17:06:42.
Reminder: Lowfer net +/- 3927Khz Saturday morning 0800 California time
Or listen online at kfs:
http://69.27.184.62:8901/?tune=3927lsb
or
KPH Point Reyes:
http://198.40.45.23:8073/
or
Utah Web sdr:
http://www.sdrutah.org/websdr1.html
If you cannot get into the net on 80 meters you can listen on KFS and participate by sending net control your thoughts to wa6owr@gmail.com
73
Re: 27th/28th March HiFERs
Jerry
Posted by John Davis on April 02, 2021 at 18:50:02.
In reply to Re: 27th/28th March HiFERs posted by John K5MO on April 02, 2021
I'll second what John said about a write up. The radio certainly seems to have generated much enthusiasm in online reviews; but apart from lots of comments on ergonomics and how well thought out the AGC is, there's not really a lot of other technical details.
The MDS spec is not the greatest, for instance, but would probably be OK with an LF upconverter. However, we know nothing about the radio's local oscillator tolerance or stability, both of which are critical factors when using an upconverter. (Not to mention when receiving 22 meter QRSS or WSPR.) I noticed in one YouTube video that Shannon Radio sounded a bit Donald Duck-ish when the rig was tuned to the nominal frequency. It would be great to have practical information on that factor.
Also, it appears the USB port is only for charging the battery, while the designated I/Q port seems to be baseband audio via a 1/8 inch stereo connector. Are those guesses accurate, I wonder, and what is the bandwidth of the I and Q signals? Will the I/Q output be damaged if one accidentally connects a mono plug there, as can happen if one inserts a mono headphone plug into the audio output jack? (Note: Please don't destroy the radio while trying to answer that one!)
HiFER Bonanza
Posted by John Davis on April 02, 2021 at 23:56:59.
A new HiFER signing SE turned up in CW this afternoon about 13555.380, just above JB which was also visible every six minutes, as usual. Anyone want to take credit?
Also, the seasonally returning mystery beacon F showed up in CW on 13555.120, about 140 Hz above WV. Both were quite loud at different times.
And the now-regular unknown, PLM, was solid in QRSS3, sometimes strongly enough to be audible. More on today's activity later.
John Abby beacon frequency change
EM27kc
Posted by Chris on April 03, 2021 at 16:51:02.
Abby beacon is now back on the Air. New Frequency should be at about 1364750~
Re: Abby beacon frequency change
Posted by Chris on April 03, 2021 at 16:51:50.
In reply to Abby beacon frequency change posted by Chris on April 03, 2021
My bad it should be 13564750~
Re: 27th/28th March HiFERs
Posted by Ed Holland on April 04, 2021 at 06:14:45.
In reply to Re: 27th/28th March HiFERs posted by John Davis on April 02, 2021
Thanks to both for expressing an interest.
I will attempt a review that addresses the points made already, and start a thread here specifically about the receiver, observations and experience gained in it's use.
The Belka arrived as promised on Monday last week, a somewhat short time yet to get acquainted. First impressions have been good, even if listening conditions were not the best. To get it out of the way first, ergonomics: for such a small unit with but 5 controls, configuration does allow for ready access to modes, volume, filters, memories etc., which I learned quickly. That meant I was tuning around and listening to the radio in short order, without having to fumble around for instructions.
Sensitivity with the supplied whip seems good (no direct comparisons made yet with other radios). On the example I have, tuning is absolutely spot on e.g. tuning broadcast stations and WWV in sideband appear to resolve at zero beat when dial frequency corresponds to carrier freq. Stability not monitored quantitatively, but no noticeable deviation has been evident over, say 1 hour. Tuning rate offers several options, from fine steps of 10 Hz, to large jumps provided for whizzing up and down the whole range of coverage. The encoder control has quite an "analogue" feel to it - tuning has the control of a very good communications receiver. Audio sounds very good, using a set of Sony earbuds that I trust for music listening. The radio is undoubtedly fun to use, tiny, and inherently portable - I will try not to lose sight of this latter point in the ongoing assessments, but by virtue of features and initial impressions of its quality, it does invite comparison to some of my favourite desktop receivers.
Points then, to pick up in more detailed study:
* Bandwidth settings & performance
* Operational evaluation in different modes
* Large signal/large antenna performance
* Spurious responses
* Care and feeding, connectivity and caution in operation
* I-Q signal evaluation
* USB functionality
* Use with LF converter (Ham Radio Kits version with 530 kHz LPF and up conversion to 4 MHz)
* Selective comparisons to other radios
Please let me know if there are additional areas of interest.
Cheers and 73
Ed
Re: HiFER Bonanza
Posted by John Davis on April 04, 2021 at 06:17:08.
In reply to HiFER Bonanza posted by John Davis on April 02, 2021
Sometime in the afternoon on Saturday, SE apparently decided to change frequency and moved down to near 13555.120 kHz, just a few Hz above F. A random ditter was also present at times, making for a royal jumble of IDs until the latter two finally faded away.
Re: HiFER Bonanza
Posted by John Davis on April 04, 2021 at 20:13:49.
In reply to Re: HiFER Bonanza posted by John Davis on April 04, 2021
Whaddya know? SE and F turn out to be the same signal...if you cstch them both in the same passband, they form a quick "tweedle-deedle" sound that's an FSK signal in standard speed Morse, which (unfortunately) is keyed off between transmissions, leaving the hearer no way to sync up his ears or determine which characters are being sent as the "mark" frequency. If mark is high, then the ID is meant as "SE" but if it's inverted (mark low) then it's "F." I'd like to record it so you could make up your own mind, but today so far, the signal hasn't been strong long enough at a time to crank up the recorder before the next prolonged fade hits.
Apparently. the intended Δf is 85 Hz, but yesterday morning it was up to 170 Hz, and just before sunset it was <10 Hz.
Re: Abby beacon frequency change
Posted by John Davis on April 04, 2021 at 20:33:01.
In reply to Re: Abby beacon frequency change posted by Chris on April 03, 2021
Seems to be a good quiet spot, Chris. ABBY was good aural copy when I checked at 11 AM CDT, and weaker but still recognizable when I tuned in again a little after 1 o'clock.
New operator for ROM?
Posted by John Davis on April 04, 2021 at 20:43:34.
VE3VBA? Today's the first time since my WSPR-X started working again that I've gotten a complete WSPR transmission slot from ROM, and it was a bit of a surprise:
1820 -26 0.6 13.555361 0 VE3VBA EN58 7 1830 -22 0.9 13.555363 0 VE3VBA EN58 7 1850 -21 1.0 13.555364 0 VE3VBA EN58 7
Re: New operator for ROM?
Mea culpa. Forgot to change the text in-house beacon test call before it went on air. VE3VBA is the vanity club call used by the former Thunder Bay Coast Guard Radio/VBA ARC. Lori, VE3VAI, worked with me at VBA and he became the current licensee sponsor/holder when VBA was shut down in 2015.
73.
Re: New operator for ROM?
Posted by John Davis on April 06, 2021 at 13:42:56.
In reply to Re: New operator for ROM? posted by Robert, VA3ROM on April 06, 2021
Cool. I noticed all was back to normal yesterday:
1740 -21 -1.2 13.555348 -1 VA3ROM EN58 7 1750 -27 -1.3 13.555347 0 VA3ROM EN58 7 1800 -26 -1.4 13.555349 0 VA3ROM EN58 7 1810 -25 -1.3 13.555350 0 VA3ROM EN58 7 1820 -25 -1.2 13.555351 0 VA3ROM EN58 7 1850 -25 -0.9 13.555353 0 VA3ROM EN58 7 1900 -22 -1.0 13.555353 0 VA3ROM EN58 7 1910 -25 -2.1 13.555353 0 VA3ROM EN58 7 1920 -23 -1.1 13.555354 0 VA3ROM EN58 7 1930 -29 -0.8 13.555354 0 VA3ROM EN58 7 1940 -26 -1.9 13.555354 0 VA3ROM EN58 7 1950 -23 -0.8 13.555354 0 VA3ROM EN58 7 2000 -22 -1.5 13.555355 0 VA3ROM EN58 7This was the best reception I'd had of ROM for some time. Over the past couple of weeks, propagation has been erratic at best...the signal would fade in for a minute or two, then be gone again for 10-20 minutes. Much more nearly consistent levels yesterday.
Re: HiFER Bonanza---or maybe Bananaz!
Sunday evening I got a recording, but guess what--this time SE is low (space) and F is high (mark)! The attached file includes 13555.120 and .205 kHz in the same filter passband, then the same signal filtered to pass only the lower frequency tone, then finally the higher tone only. Click the Attachment 1 link below this message.
Evidently, the unknown operator was playing with inverted FSK for a time on Saturday because "F" was the lower one at that time and "SE" was on the high side!
The 13555.120 frequency is near 13555.070, which is where "F" appeared at my last previous logging on the evening of May 30, 2020. Back then, as near as I can tell from listening to the old recording, it was plain CW at about half the speed. That earlier recording is available at:
lwca.net/mbarchiv/pix/2020/F.mp3
In corresponding with another listener who copied F a few times in recent weeks before I did, it does apparently normally use the mark-high sense, so Saturday was an aberration.
Why anybody would use FSK for normal speed CW on 22 meters in the first place, and then compound the confusion by unkeying the carrier between idents, is as big a mystery as the origin of the signal. The listener doesn't have time to sort low from high tones before they're both gone! Most of us are not human modems; our ears do not immediately jump in 85 or 170 Hz steps. If one is going to waste bandwidth with FSK CW, then why not let the space tone remain on long enough to be self-evident what the mode is and serve to make the mark tone stand out?
---------------------------------------------------------------
File Attachment 1: 4apr_F_se.mp3
BELKA DX HiFERs
I was stuck at home yesterday, feeling the rather severe after effects of vaccination. This did offer a chance to test out the BELKA receiver on the HiFER band, and coincided with some decent propagation conditions.
Monitoring started with the Icom R-72, to establish an informal baseline, before switching to audio from the BELKA. I was happy to note the following points:
* Stability is excellent. I haven't tried WSPR decodes or other modes of the same ilk yet, but there is very unlikely to be any difficulty. The tiny receiver was within a few Hz of the Icom, and may well be demonstrating higher dial accuracy.
* No Surious signals in the vicinity of 13,560. Belka does have a few birdies, but nothing to trouble beacon listening.
* Excellent performance on the "Random Wire Dipole" and the inverted L. No overload issues noted.
* S/N looked good in spectrum lab. Using the headphone O/P I set the volume to put the noise floor at the same level as the Icom. As conditions allowed, signal traces popped up with excellent clarity - Screenshots when I have time...
* Very flat passband (USB mode) - no noticeable variation in the noise floor as observed with some receivers using ceramic filters.
* Plenty of battery life for longer monitoring sessions.
In closing, I continue to be impressed and pleased with this acquisition - it is certainly a very capable machine for beacon work, and it would be interesting to try mobile reception with just the telescoping antenna, and do some Hilltop HiFERing (for as long as the laptop batteries keep-up).
73,
Ed Re: Lowfer SIW QRT
Posted by swlem3 on April 09, 2021 at 19:20:47.
In reply to Re: Lowfer SIW QRT posted by Mike N8OOU on March 28, 2021
Hi Mike,
I just saw this post you've made about wind speeds needed for the turbine and your lack of 20-25 mph winds. I couldn't resist commenting and sharing this pic. I should have named my qth "Windy Acres" because it's rare to have little or no wind here. Great in the warm wx, but that wind becomes a "foe" as soon as the temp drops when summer is over.
drive.google.com/file/d/1xWdf84MI5clWosjl5l_dGXPwwewTl7Qb/view?usp=sharing
Notice the tree foilage is pretty "sparse" on one side? That is the southern facing direction. The wind is always so prevalent here that it has deformed the tree. That same tree gets blasted from the opposite direction once late fall sets in, but by then it's lost it's leaves.
Guess I should get a wind generator, eh? :-)
MN back on the air
Posted by KMONAS on April 09, 2021 at 19:51:50.
Hello All,
I just realized today that MN was off the air. Not sure why. A quick power cycle and it woke back up. Hopefully you will be able to hear it again now.
~Kirk
Re: Lowfer SIW QRT
Posted by Mike N8OOU on April 10, 2021 at 01:19:14.
In reply to Re: Lowfer SIW QRT posted by swlem3 on April 09, 2021
Good Evening Ray;
Yes, that tree makes it look like you could host a windmill farm.
Mike 73 Re: Lowfer SIW QRT
Posted by swlem3 on April 10, 2021 at 02:05:24.
In reply to Re: Lowfer SIW QRT posted by Mike N8OOU on April 10, 2021
Good Evening Mike... yep, maybe I should turn this qth into the neighborhood generating station, sell electricity and make "windfall profits" ... hi.
73,
Ray
TUK Nantucket
Posted by Edga Heinen on April 12, 2021 at 21:28:27.
Does anyone remember hearing TUK beacon from Nantucket? How far away was it copied in the DAYTIME? I was able to hear it well in Toronto at night, but did not try for it in the daytime. It was 4 kilowatts.
WGU20
Posted by Edgar Heinen on April 12, 2021 at 21:34:52.
I was able to get WGU20 on 179 khz in Toronto in the daytime but it was closer than TUK Nantucket, and 50 kw, instead of 4 kw for TUK.
Re: BELKA DX HiFERs
Posted by John K5MO on April 13, 2021 at 11:52:33.
In reply to BELKA DX HiFERs posted by Ed Holland on April 06, 2021
Ed, thanks for taking the time for the review. I may very well jump on one of these . I was looking at some shortwave receivers on Amazon ("SI4732") but although the price is attractive the few reviews I found are pretty bad. On the other hand, your review of the Belka shows it to be quite capable.
How long did delivery take? I'll be interested in your screen shots.
Whenever I see a small portable radio with a telescoping whip, I assume that when hooked to a conventional dipole it'll be overload time. Did you notice any such thing?
John
Re: BELKA DX HiFERs
Posted by Ed Holland on April 13, 2021 at 18:54:53.
In reply to Re: BELKA DX HiFERs posted by John K5MO on April 13, 2021
Hi John,
Delivery was about a week. I paid with Paypal, and received all the usual encouraging email feedback.
Connection to the external antenna didn't cause any immediate problems with overload that I noticed. There's a sensitivity control, in the manner of RF gain, but it doesn't act on the AGC in the normal manner of an analogue set. It may be that strong signals were in short supply during the test, but the results were encouraing.
This weekend, I tried going mobile, in search of HiFERs at the horse barn. Mid-day is not typicaly a good hunting time, and nothing was received on this occasion. Another factor here was interference from the PC. A different antenna and counterpoise arrangement is needed to prevent reception of objectionable harmonics from the computer. This was noticable as a jump in baseline s-meter reading on connecting just the grounds of receiver and laptop, and would be an issue with any portable receiver. I have a few ideas for experimentation next time.
Ultimately, I want to compile my findings into a more complete set of observations.
Request for screenshots noted.
/Ed
Re: noise canceller schematic question
Posted by swlem3 on April 16, 2021 at 01:58:00.
In reply to Re: noise canceller schematic question posted by John Davis on March 15, 2021
John, Lee... I finished building the canceller circuit according to the schematic and the changes that John suggested (isolating/separating grounds). Here's the finished product:
drive.google.com/file/d/1QiK0YBZSgJjgPZus0JxUsthVdfBf4EXj/view?usp=sharing
The good news first: It does work, and for a very nominal cost, cancels the main local qrm pest that plagues this other-wise wonderful rx location. That pest is present 95 percent of the time at this qth, and adds roughly 12db of noise when present, making dx impossible to decode on 2200m. It is power-line related.
The bad news is that was difficult to find the null. Too many "variables" that had to be dealt with when trying it out for the first time.
Variables:
The noise antenna, which position to place the two double pole switches, rotation positions of the two "pots". It took a good while to find the EXACT place on the 1k pot that produced the null. I had to play with every variable until I found the only combination that produced cancellation of the noise, and there is only ONE combination for the two antenna I use.
In my particular two-antenna situation, the unit only worked with the capacitor switched in, thus by-passing the 500 ohm pot. Null came from carefully adjusting the 1k pot.
My noise antenna is a vertical wire with an auto-transformer matching it to coax. The main antenna is an active probe.
More bad news... Since I've got it working, the activity on 2200m has dropped to near nil. The 'spherics have been horrible here in Texas since then also. The bottom line is that I've had no opportunity to use it. Oh well, such is life. Just have to "wait it out" until better conditions come along.
Btw, I tried both core mixes. The author used a 43, my first core made used a 77. They both worked. I settled for completing the project using the 43 like the schematic shows.
I should try it up a bit in freq on the lowfer band. Hope it will work there too. Since the unit does work, I thought of making one for the 630m band. I've already tried the unit there, and it doesn't work with the present parts values. Maybe all it would take is to reduce the value of the capacitor in the circuit. If so, perhaps I could just add another switch to the circuit to change cap values.
Re: noise canceller schematic question
Posted by Lee on April 17, 2021 at 00:48:34.
In reply to Re: noise canceller schematic question posted by swlem3 on April 16, 2021
Glad to hear it worked. I have no experience working with noise cancellation circuits. My location is extremely noisy. Next season I plan to try a commercial NC system of some kind. You are correct. 2200 meters has dropped of the map as of late. Perhaps John has some insight into the iffy adjustment of the circuit.
Re: noise canceller schematic question
Posted by swlem3 on April 17, 2021 at 01:26:08.
In reply to Re: noise canceller schematic question posted by Lee on April 17, 2021
Lee, you're right about 2200m dropping off the map. It's to be expected though. High qrn levels are here and ops just choose to move up in freq rather than fight a losing battle with the noise.
On the critical adjustments of the canceller, I think it's just the "nature of the beast". Anytime you build something like this, there's bound to be a learning curve involved. With the commercial units they've done all the hard work in design and basically all you have to do is supply an adequate noise antenna. I think you'll find the commercial NC's will help you out with the noise you have.
73, Re: noise canceller schematic question
Ray
Posted by John Davis on April 17, 2021 at 16:54:51.
In reply to Re: noise canceller schematic question posted by swlem3 on April 17, 2021
Just wondering, Ray...how far apart are the two antennas?
Re: noise canceller schematic question
Posted by swlem3 on April 18, 2021 at 00:32:45.
In reply to Re: noise canceller schematic question posted by John Davis on April 17, 2021
John, the two antennas are roughly 100ft apart. I think I may have "rejoiced" too soon concerning the seemingly good noise null. I've been testing the canceller without signal, mainly because until today, there have been no actual signals to decode. I have a suspicion that the unit is simply nulling whatever freq I am tuned to, making it appear that it's cancelling noise, when in reality it's nulling noise and signal, if that's possible. WH2XND is back on the air and I'm using that signal for my tests. I'm seening no improvement with the box in line, in fact, it seems to be worse that just using one antenna and decoding through the noise. :-(
Re: noise canceller schematic question
Posted by John Davis on April 18, 2021 at 06:04:28.
In reply to Re: noise canceller schematic question posted by swlem3 on April 18, 2021
I have a suspicion that the unit is simply nulling whatever freq I am tuned to, making it appear that it's cancelling noise, when in reality it's nulling noise and signal, if that's possible.
Alas, it's very probable. I hope you won't be discouraged to hear that news. In fact, in one sense, the results you reported are a sign that your construction techniques are sound and the inductors are well matched. A commercially made unit would not be able to do any better job, apart from maybe making the null point a little easier to locate...and even that is iffy, given the antennas being used.
The first thing that puzzled me in your report was that the phasing adjustment had no effect at all, despite the ability to achieve a deep null with the amplitude match alone. Then I re-read the part about both antennas being verticals, and it dawned on me: unless there's adequate physical separation between two inherently omnidirectional antennas, there will be almost no phase difference between them for either the received signals or the unwanted noise. If you cancel one, you will cancel the other by the same amount, within a tiny fraction of a decibel.
With two verticals only a hundred feet apart, the phase difference between them for noise-vs-signal at any frequency in the 2200 meter band cannot exceed 5° tops. Even at 630 meters, that spacing can only achieve a maximum of 17° between wavefronts, and only if one source is arriving along the axis of the array and the other is arriving perpendicularly. That's barely enough to null 1 dB of noise.
To overcome that limitation will require one of three things to be the case (and this will be true whether the circuit is homemade or commercial):
1. If the noise sense antenna can be placed nearer the offending source than the signal antenna, and if it still picks up a sufficiently identical copy of the noise, then in principle, it should be possible to null the noise via amplitude adjustment alone before all the signal is also cancelled. But that's a very big "if," and unless the noise source is near enough to your own QTH it may not be possible at all.
2. Make the array more directional by spacing the antennas 1/4 to 1/2 wavelength apart. Unless signal and noise are arriving from the same direction (in which case the phase relation between them remains the same), this gives you a fighting chance of distinguishing between them. That works well enough at HF, but there are obvious problems with that kind of spacing at 2200 m.
3. Make the array directional by using a loop for one of the antennas. Since the loop will output the opposite polarity for signals arriving from opposite directions in its main lobes, this gives you the maximum number of chances to find a null; not to mention, the loop may allow you to determine the direction of the offending noise itself if it's originating from a single discrete source. The downside of a loop is that it ideally should be rotatable to give you maximum flexibility; but with a phaser containing a phase reversal switch like this design does, it only needs to turn as little as 90 degrees to cover all bases. (A more advanced phase shift network could conceivably allow you to use two fixed loops crossed at right angles, with or without a vertical antenna, but that's probably overkill.)
John
Re: noise canceller schematic question
Posted by swlem3 on April 18, 2021 at 14:56:42.
In reply to Re: noise canceller schematic question posted by John Davis on April 18, 2021
I am sort of discouraged with this John, simply because of the time/energy spent on something that probably won't produce results expected. If nothing else, it was a learning experience. Yes, I was also puzzled by the fact that the phasing control did nothing in this situation.
Your third option seems to be the only one that would be feasible/practical for me. In the write-up article that came with the schematic, the authors second antenna was a fixed loop that was aligned toward the noise source. I was hoping that a simple vertical wire would work as the noise source, but the results fell victim to the antenna separation situation you've described.
I've read about the crossed-loops. I think, in times past, a ball variometer was used (not easy to construct) to electrically shift phase. Now, more advance versions of phasers are employed in it's place. Either way, this is probably "overkill" as you mention... time/energy/money.
From this point of time, I'll have to consider whether more time/energy should be used to pursue the phaser project. It might just be more "productive" to make a simple tuned loop for the frequency of interest and null the noise by mechanical rotation.
Re: noise canceller schematic question
Posted by Lee on April 18, 2021 at 17:46:31.
In reply to Re: noise canceller schematic question posted by John Davis on April 18, 2021
Thanks John. Great insight. I guess I will pursue my initial idea of having a second tunable ferrite loop antenna that is switched in or out by the transmitter keying signal. I did find a product but the manufacturer name escapes me. I do remember it was pricey.
Re: noise canceller schematic question
Posted by John Davis on April 19, 2021 at 20:02:49.
In reply to Re: noise canceller schematic question posted by swlem3 on April 18, 2021
In the write-up article that came with the schematic, the author's second antenna was a fixed loop that was aligned toward the noise source.
That may be worth a try, and could be simpler than it sounds. Not having seen the write-up, I don't know how elaborate a loop the author used, but it shouldn't have to be anything fancy to test the feasibility of the idea. An untuned loop of a few feet in diameter, consisting of one to five turns (depending on the dimensions of the loop), feeding a simple low impedance pre-amp, ought to do the trick. There is no need to shield the loop, provided it is kept in good electrical balance with respect to ground and is several feet from people or other disruptive objects.
One suitable loop pre-amp is the MØAYF design as modified by Steve Ratzlaff and implemented by Todd Roberts:
lwca.net/library/articles/wd4ngg/rcvloop/index.htm
It's a bit on the deluxe side, but works from LF through HF. A simpler and less expensive one is the old, reliable Ralph Burhans design that was the basis of a project by K3SIW. It's limited by its transformer response to LF, but does a splendid job within that range. If you are remote enough from any potential AM broadcast overload, you can even do without the L1-C1-C2-C3 trap circuit.
lwca.net/library/articles/k3siw/rcvloops/index.htm
As for constructing the loop itself, both of these projects are probably overkill. A diamond shaped loop on some crossed sticks on a non-conductive mount should be adequate to test the idea. Before committing to anything permanent, you'll be able to confirm whether the noise is from a single source having one predominant direction or not. If the origins are too spread out, directional nulling may not be able to help.
The advantages of an untuned fixed loop (versus a tuned one) for the "noise antenna" with a nulling circuit like this are twofold:
1. You don't have to retune for every frequency, which is not only an obvious inconvenience in its own right even when using a loop alone, but when also using a noise canceller, every tweak of the loop tuning requires readjustment of the phasing control and sometimes amplitude as well.
2. You end up with a pattern having only one null and a substantially cardioid pickup for all other signals. With a loop alone, you have two major lobes and two nulls--one in the direction of the offending signal, and another directly opposite it, which may well be the desired direction of reception sometimes.
Hang in there, Ray. As Red Green used to say on TV, "we're pullin' for ya."
John
(P.S. - I wouldn't take down the passive vertical "noise antenna" just yet, myself. There is just a chance it might prove to be a useful LNV antenna on its own.)
A quiet weekend
Posted by Ed Holland on April 19, 2021 at 20:17:49.
Hi Folks,
Rather little to report from 17/18 April daytime monitoring. Saturday was notable in yielding only the feintest, brief trace of what seemed to be 7P
Sunday was quiet nearly all day, except for an early (local) evening appearance of NC, and a snippet of what could have been WM. 7P appeared too, and endured until monitoring ended around 7:30PM PDT.
I had hoped to test the Belka DX receiver in mobile mode (well, in the garden anyway), using a homebrewed tuned loop antenna. This certainly gave some improvement in reducing conducted interference from the laptop when compared to the telescopic antenna. Alas, there were no HiFERs reaching California to enable comparison of reception quality with the fixed installation dipole antenna, and full size communications receivers. All I can say is that the system tuned up nicely on the atmospheric noise at 13,555 kHz, so expectations are that it could yield beacon observations in a portable configuration. The antenna is a square of 12 ga wire 3 ft on the diagonal, tuned to resonance with a 15-150 pF variable capacitor. Feed to the receiver is via a coupling loop ~ 12" diameter. It has previously been tested suspended from a tree at about 4 ft off the ground, and connected to the radio desk with 75 Ohm "TV" coax. It worked surprisingly well for HiFER reception on that occasion.
Re: noise canceller schematic question
Posted by swlem3 on April 20, 2021 at 04:04:14.
In reply to Re: noise canceller schematic question posted by John Davis on April 19, 2021
With your addition information John, I think I'll pursue the untuned passive loop suggestion. Since I've already built the canceller, a simple small untuned loop isn't that much more work. Good idea about using the loop to see if the noise is from one confined direction, or more spread out before investing too much time on something the canceller won't work on. As you say, if it does work, I'll have the advantage of the null in one direction only, instead of two. Murphy's Law states that noise nulls will generally be found in the same direction as the dx you're attempting to copy, so no sense in giving Murphy better odds. ;-) You're right about the utility of the vertical noise antenna. It seems to provide decent general frequency coverage.
I'm going to get back to work and will report back when I have whatever results are to be had.
Thanks for the time taken to pass along this info John, and for the encouragement to keep 'pluggin away at it.
Ray
Re: BELKA DX HiFERs
Posted by John K5MO on April 24, 2021 at 20:24:04.
In reply to Re: BELKA DX HiFERs posted by Ed Holland on April 13, 2021
Just ordered one Ed.
Got an almost immediate conformation from Alex. Can't wait to give it a try!
John
Re: BELKA DX HiFERs
Posted by Ed Holland on April 26, 2021 at 17:43:46.
In reply to Re: BELKA DX HiFERs posted by John K5MO on April 24, 2021
Great - I'll be very interested to compare notes with you.
Ed
potrzebie