Past LW Messages - May 2020

Re: Live NDB in southern California
Posted by Steve Ratzlaff on May 01, 2020 at 01:28:22.
In reply to Re: Live NDB in southern California posted by Lee on April 12, 2020

385 MR Monterey is on; 397 SB San Bernardino is on; 404 MOG Montague just got repaired and came back on couple months ago.
Steve AA7U

Searching for old Lowdown article
Posted by Jim Davey K8RZ on May 01, 2020 at 01:48:40.

Anybody have old issues of Lowdown that could find this article, author unknown:
"Analysis & Design of Broadband Low Frequency Loops," Lowdown, April and May 1985
Saw it referenced in a Lloyd Butler, VK5BR, article on VLF loops

Re: watering hole lowfers
Posted by Mike N8OOU on May 01, 2020 at 02:28:33.
In reply to watering hole lowfers posted by Garry, K3SIW on April 30, 2020

I didn't realize that high winds a couple days ago broke the antenna again. I found Low PA current this afternoon, then discovered and fixed the broken connection at the helix can. I believe WM is back to normal now.

My trees are forming small leaves, Red Buds are red budding, and Maples are making helicopters. Hows mt signal holding up?

Mike 73

Reminder: Lowfer net +/- 3929Khz Saturday morning 0800 California time
Posted by Jerry Parker on May 01, 2020 at 16:36:17.

Reminder: Lowfer net +/- 3929Khz Saturday morning 0800 California time

Or listen online at kfs:

http://69.27.184.62:8901/?tune=3929lsb

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,

Jerry WA6OWR

Re: Former BUH/BUV
Posted by John Davis on May 02, 2020 at 04:29:22.
In reply to Re: Former BUH/BUV posted by John Davis on April 25, 2020

Success! About half an hour after sunset tonight on 13564.920 I began seeing CW about 115 Hz lower than K6FRC on the same Argo screen. It was distinctly slower keying than FRC, and at a little lower signal strength, which combined to make it significantly harder to copy by ear through the rather rough Codar that was present at the same time. I kept checking back over the course of 20 minutes, during which I copied R several times, T a few times, and finally a couple of G's too. Never got an entire call all in one piece, but the cumulative result was a reasonably certain ID.

Elsewhere in the 8 PM CDT hour, EH and RY were alone (and quite bright) at the watering hole, and WAS was ranging from weak to fair copy. Nobody else that hour.

Three hours before, however, EH was absent but NC was intermittently strong; one letter at a time showed up from PVC, 7P was jumpy in frequency but visible for one or both characters at a time, MTI was fair to strong, WV was fair to good, VAN's DAID fishhooks were showing, FRC was fair, WAS was good, ODX was fair to good, and ABBY was recognizable. Late afternoons and evenings have definitely been a lot more productive than mornings the past several times I've been to the field.

Re: Former BUH/BUV
Posted by Chris kc3gfz on May 02, 2020 at 19:26:50.
In reply to Re: Former BUH/BUV posted by John Davis on May 02, 2020

Nice to see the all these beacons are getting out! I have notice on the propogation graphs showing better results in the evenings then mid or early afternoon.

Chris

Re: Searching for old Lowdown article
Posted by Kevin Carey on May 04, 2020 at 18:24:53.
In reply to Searching for old Lowdown article posted by Jim Davey K8RZ on May 01, 2020

Here at LWCA Headquarters, we have a limited supply of back issues. Copies of articles are available to current LWCA members.

The April 1985 issue does not contain an article on Broadband Loops. Please double-check the reference to make sure the dates are correct and let me know. The title of the article does sound familiar to me.

WANTED - users of Bendix DU Loop Antennas
Posted by Joe Long / WA2EJT on May 06, 2020 at 18:29:20.

I am writing an article for Electric Radio magazine on the pre-WWII Bendix family of loop antennas - the DU, DU-1 and DU-2. I am looking for others who own any of these loops. I am especially interested in serial numbers on any of these units in order to improve my estimates on the numbers of these loops that were manufactured.

I have owned a DU-1 for a number of years now and have done a lot of listening with it and I and would like to hear from other folks who have used one.

Thank You and 73, Joe Long / WA2EJT

Notes on 2 May, 2020 LowFER net
Posted by Clint Turner KA7OEI on May 10, 2020 at 21:31:26.

LowFER Net Notes for 2 May, 2020.
(+/- 3929 kHz Saturday morning 0800 California time)

Present were:
Jerry, WA6OWR; Clint, KA7OEI; Mike, N8OOU; John, AE0CQ

Remember: You can participate virtually by listening to the KFS WebSDR - go to http://69.27.184.62:8901/?tune=3929lsb (+/- if QRM) and sending email comments during the net to Jerry via wa6owr@gmail.com

Jerry:
• Plans to dedicate an acquired laptop for the SDRPlay Duo
• Hoping that with the diversity reception and the MLA-30 whip that he will be able to fight some of the QRM.
• Got whip back up - ended up with S-5 noise on it: Will work on mitigating this/finding source of noise.
• Working on the MLA-30 loop:
  • Replacing flimsy stainless steel loop of the MLA-30 with something more substantial (heavy copper wire) with mechanical support.
  • Apparently, things can flex and break the box and PCB unless the loop itself is supported.
  • When using it remotely with a TV rotator, Jerry noted that others report that these are a bit too fast to catch the loop's null - need something that rotates a bit slower.
    • Clint commented: Many modern antenna rotators use DC permanent-magnet motors, but reducing voltage to slow down tends to reduce torque which may make them unreliable in starting.
    • One can use a 555 timer or similar to produce a PWM voltage on motor supply to give it full-voltage pulses at a lower duty cycle to help maintain torque but lower rotation speed (suggested about 25% Duty Cycle at 60-200 Hz).
  • In the message board, there isn't much of a consensus as to weather the loop works better elevated or near the ground. Near the ground has an obvious advantage
  • Plans to mount loop (get comments on description)

Clint:
• Not much time on LF this week - limited "listening" at home - didn't really have local (home QTH) receivers running as computer was tied up doing other things.
  • KA7OEI-1 at the Northern Utah WebSDR is still (occasionally) catching VK4YB on 630 during evenings where the thunderstorm activity in the middle of the U.S. is lower. It's often catching AK and HI.
  • Even though the nights are shorter, good conditions on LF/MF can still exist - but often masked by mother nature's spark gap transmitters!
• Did some work to tweak the Northern Utah WebSDR:
• Added an extremely sharp 40 meter band-pass filter (> -20dB below 6.9 and above 7.4 MHz) to mitigate interference from extremely strong 41 meter SWBC just above the ham band.
  • Individual signals from the east-pointing beam can peak above -15dBm with the total power from multiple signals exceeding that, overloading the 40 meter receivers.
• Installed high pass (>1.8 MHz) and low pass (<40 MHz) filtering on the beam to filter AM and FM broadcast stations.
  • Need to revisit the filter as 30-35 minimum attenuation isn't quite enough to adequately quash levels from some of the 10kW and 50kW "local" stations as even after that, signal levels can approach -20dBm from KSL (1160 kHz) which has a 5/8 monopole separated from the WebSDR site (mostly) by salt water.
  • Either need to rebuild the filter or add frequency-specific notches.
• Participated in ARRL FMT: Was able to measure 40 meter frequency to better than 0.2 Hz, 80 meter frequency to better than 0.02 Hz.
  • Appreciated comments from both Mike and John on my results.
  • I'd nearly missed the 80 meter FMT transmission - had only about 10-15 seconds of K5CM signing off in CW to measure the frequency.
• Got QRM-180 phase-type noise cancellation kit from EvilBay (just under $100 including shipping and taxes) - plan to put it together in the next week.
• Remote receivers at KPH have been offline for the past week or so.
  • Unknown network problem - but since it is run by the National Park Service it is closed due to lockdown. A request was made to go there to investigate, but it was denied.
• Wondered about how the SDRPlay Duo diversity reception actually worked: How does it "know" what sort of signal to favor?
  • Does it simply look for the strongest signal between the two and present it to the user, or is it possible to phase them in software to null noise or the "undesired" signal?
• Commented on loop construction:
  • Have built loops using 10-12 feet of 1/2" Heliax cable - a break in the middle of the shield for balance.
  • Used the ubiquitous gray electrical boxes with 1" NMT (plastic) conduit attachments, top and bottom.
  • Constructed a "Tee" to support the heliax loop portion out of plastic: Used 1"->3/4" bull-nose "Tees", running the heliax through them for support and sealing the top side with RTV (silicone).
  • Noted that compression fittings rated for 0.5" "SO" cable (not the bigger versions for 0.6-0.75" cable) compresses onto 1/2" heliax very nicely, providing good rigidity and water-tight seal.
  • Usually hung the loops upside-down from the mount so gravity would work in favor of its support.

Mike (via WebSDR and email):
• Spent the past week cleaning up from the storm - cleaning up damage, not much radio fun.
• Found the "WM" antenna broken about noon yesterday due to storm damage. Managed to repair it by about 2 PM and reception reports resumed, with comments of it being heard again on LWCA message board.

John (via WebSDR and email):
• Having trouble getting on KFS at first because of too many users: Could hear Clint on Northern Utah WebSDR, but not Jerry.
• Persistence (reloading KFS) paid off and was eventually able to get on before much of the net had passed.
• LowFER WM was coming through pretty well last night: Barely there during the afternoon, good signal at night, although not quite as well as a month ago.
• Copied SIW the afternoon and night before.

73,

Clint
KA7OEI

Notes on 9 May, 2020 Lowfer net
Posted by Clint Turner KA7OEI on May 11, 2020 at 00:06:18.

Notes on 9 May, 2020 Lowfer net
(+/- 3929Khz Saturday morning 0800 California time)

Remember: You can participate virtually by listening to the WebSDR (KFS - go to http://69.27.184.62:8901/?tune=3929lsb +/- QRM ) and sending email comments during the net to Jerry via wa6owr@gmail.com

Present were:
Jerry, WA6OWR; Clint, KA7OEI; Dave, WD4PLI; John, AE0CQ

Jerry:
• Been playing with his SDR Duo:
  • Steep learning curve: Lots of buttons, knobs, bells and whistles.
  • Still a bit annoyed that the SDR Duo has very little input protection - but this is an artifact of its needing to be usable into the GHz range.
  • Noted that there is now the "SDR-DX" which reputedly has better performance at MF/LF.
• Has PA0RDT whip on a piece of PVC as a mast clamped to a fence pole in the dog run
  • Wants to change coax to see if noise ingress is occurring via poor shielding.
  • Has Ukrainian active whip that he can try, too.
  • Perhaps try a 108" metal pipe/whip.
  • Wants to compare the whips and loop for sensitivity - and especially noise pickup.
• Wondered how John logs QRSS reception - see comment, below, from John.
• Plans to put up 20' pipe with antenna on it, pending time and availability of a helper.
• Noted that he has pretty much all of his radios on battery when using them - computers are typically on mains power.
• 30-40 years ago, he hung a whip between trees and ran the coax into the shack with no problems: Not so much these days with lots of switching supply/noisemakers around the house.

Dave:
• Didn't make it to Starbucks today - appearing today caffeine-free!
• Reiterated grounding the active whip, decoupling it from the "shack" ground.
  • Rather than a current balun (e.g. lots of turns on ferrite) he made a 1:1 isolation transformer - powering the whip near its base as necessary.
  • For power supply, using *only* a linear supply - no switchers allowed! A battery works, although it may not always be convenient.
• Mentioned switching power supply from his Icom 7800 every 70 kHz, radiating out on the power lead into other receivers as well. Can now hear it on 160 meters - suspecting capacitors going bad.
  • Not sure if it's getting worse over time, or if it's because he's noticing it more and more - suspects a bit of both.
  • Hasn't cracked it open to see how hard it might be to work on it, but is considering it.

Clint:
• Operated 630 Meter WSPR last night - was copied by many of the usual suspects (AK, HI, back east) - but fewer stations overall are receiving.
• Recommended that one decouple the active whip coax using a current balun.
• Note that with active whips, the cable connecting it is one of the most important parts of the antenna itself - and that's often where the noise is conducted to the antenna from the shack.
  • Always ground the coax on the "antenna" side at the antenna to a "quiet" ground.
  • I mentioned that it's good to put two inline coaxial chokes/current baluns: One near the antenna to isolate the run from the shack from the "quiet" ground at the antenna, and another near the shack to prevent that coax run from conducting/radiating shack noise.
• Suggested taking receiver out to the antenna and disconnecting the cable that runs to the house - at both ends if possible - to see how noisy it is.
  • While doing this, touch the shield of the coax from the house (when it is connected) to the antenna shield of the test set up to see if noise is being conducted into the cable.
• Talked a bit about different ferrites/mixes. Type 31 mix is good for HF, probably need 73, 75 or 77 mix for LF.
  • Use RG-174 or same-sized Teflon coax jumper (RG-316) for coax choke on 2.4" diameter core (FT240 size).
  • RG-316 jumpers with connectors are available on Amazon for reasonable price. (Suggest >=1 meter lengths). Typically these have SMA connectors - may be cheaper to use adapters than buy cables with other connectors.
  • At LF/HF, one can simply get "raw" RG-316 cable and solder BNC/UHF female (chassis-mount) connectors to the ends after winding, keeping the shield connections as short as possible (RG-316 solders nicely and doesn't melt!) as it's far cheaper!
  • Recommend putting choke in one of those gray plastic electrical boxes (about 4"x4"): Connectors may be mounted to box, or coax can be brought in via notches cut in the bottom to the choke/connectors inside to make it inherently waterproof.
• Having tested 77, 31 and 43 cores as coaxial chokes, I've noted that:
  • 77 is useful (with enough turns) down below 30 kHz up to about 160 meters, losing efficacy by about 7 MHz.
  • 31 is useful from 630 meters (with enough turns) up to about 7-10 MHz, but runs out of steam above that.
  • 43 is useful from 80 meters through about 10 meters.
  • The method where one winds half the turns and then crosses over to the other side can reduce in/out capacitance coupling, but this is probably not necessary on chokes for LF/MF as the effect starts to be noticeable on 20 meters and above.
  • A very effective choke for LF through HF consists of three in series - one each with 77, 31 and 43 mix, separated by a couple of inches/cm.
• Jerry mentioned possible use of MFJ-915 coax choke: This has 50 beads on a chunk of coax, nominally rated for 160-10 meters: Probably not enough impedance for truly effective VLF/LF use.
  • A rough "Z" measurement and attenuation measurements can probably be done with a VNA, the MFJ-915 placed in series between the VNA's ports 1 and 2's and connected via the VNA's center conductors (only) to the '915's center conductors and/or coax shells.
  • Two articles on chokes:
    • https://bonoradio.wordpress.com/2018/03/19/measurement-and-comparison-of-common-mode-chokes/ - Includes MFJ-915
    • http://www.karinya.net/g3txq/chokes/
• I've been getting cores from kf7p.com (I'll admit that I personally know him and he's local to me) - his prices are pretty good compared to many others.
• KPH (Point Reyes) remote receivers (KiwiSDRs) is still offline due to unknown technical problems. Because of lockdown, a visit has been impossible: A request was made with the Park service to make a quick visit, but it was denied.

John (via WebSDR/Email):
• "Return to late winter" - frost advisory.
• Got electrical, outlets and lights wired in the "garage" on his lot - has LED lights for brightness while working on projects, but incandescent is available for RF quiet as necessary.
  • Still working on getting the transfer switch wired in for the generator.
• During excavation, has discovered that there are lots of large rocks undergound, which will complicate the burial of coaxial cables.
  • Now has limestone slabs scattered around the yard - needs to figure out what to do with them.
• Between storms and busy nights (getting the Lowdown together) there has been relatively little time for listening.
• In brief free time, copied EAR and the last transmission of the season from SIW
• Answer to Jerry's question about logging QRSS:
  • Uses the ARGO program to visually capture the screen - something that it will do automatically.
  • Every session/day, he gives a unique file name prefix - Argo then numbers the captured files sequentially.
  • Use a program like media viewer (or IrfanView) to look through the sequential files to visually "read" QRSS signals, flipping through them in order.

73,

Clint
KA7OEI

HiFER shortage.
Posted by Ed Holland on May 12, 2020 at 17:18:50.

Hi Folks,

I allowed a luttle time for HiFER listening and detection over yhe weekend. Alas, there was very little to be heard or seen. Brief fade-ins of NC and 7P on Friday, with what looked to be EH. Looking at the 13560+ side of the noise, there was nothing to be found. Even the noise was weak!

73s

Ed

Re: HiFER shortage.
Posted by John Davis on May 13, 2020 at 19:28:01.
In reply to HiFER shortage. posted by Ed Holland on May 12, 2020

As if toilet paper, sanitizer, and meat weren't enough. now there's RF hoarding too?

C'mon, people, turn off those radios when you're done using them. Leave some signals for the rest of us!

vlf antenna question
Posted by James Fisher on May 15, 2020 at 21:10:43.

I have a question about a magnetic loop antenna for the 600 meter band. The pacific 66 antenna calculator gives a efficiency of 10% for the loop similar to what I am contemplating building. The calculator gives this estimate for a round loop. I plan to build a rectangular loop. Due to the high efficiency of the proposed loop, I need to actually measure the eirp so that i can stay compliant with fcc regulations limiting radiated power to 5 watts. Do you have any info on actually measuring eirp that a person who does not hold an advanced degree in math can understand? Has anyone actually measured the eirp of a vlf antenna, and how did they do it. I hope someone has info, My vlf transverter is waiting vibrating with anticipation!

Re: vlf antenna question
Posted by Mike N8OOU on May 16, 2020 at 00:15:04.
In reply to vlf antenna question posted by James Fisher on May 15, 2020

Jim,

I have built and tested transmitting loops for the 2200, 1750, and 600 meter bands. I have tried a number of loop sizes and mounting positions. I have convinced myself, that small transmitting loops work, but loaded verticals work much better. I am not sure of your design of a high efficiency loop, The largest I put up was 300+ ft circumference of RG8. Pacific says that loop at 600m was 16% efficient.

My guide for loop design and construction was based on a two part paper created by William (Bill) Ashlock sk. Those papers can be found on the internet.

To address your question, I'm sorry, can't help. I don't have the engineering knowledge, or necessary equipment to perform eirp measurements. My interest in this aspect of the hobby is totally geared toward the weak signal aspect. Even in these bands transmitting mW can provide super results.

73 Mike

Re: vlf antenna question
Posted by Eric NO3M on May 16, 2020 at 17:36:35.
In reply to vlf antenna question posted by James Fisher on May 15, 2020

What are the dimensions of your proposed loop? The efficiency is not 10%. See this reference (pg 22):

https://rudys.typepad.com/files/chapter-4-2.pdf

"Even if we used super-conducting wire the efficiency would still be limited to ≈4.2% due to near-field ground losses"

The only way to get above that is to transform the loop into something different, using loading inductors, as Rudy demonstrates, which changes the whole behavior of the "loop" into a pair of in-phase verticals (and the pattern).

The calculator you are using appears to be overestimating Rr (prob due to the fixed octagonal layout vs. a rectangle, ergo larger enclosed area) and what is this "loss resistance" they show... conductor loss, capacitor loss, ground/environmental loss, all these losses combined???? They are calculating efficiency as Rr / "loss resistance" using an absurdly low "loss resistance" that is not defined. Therefore, the efficiency is going to be wildly off.

No calculator is going to get Rl right anyways, too many unknown and widely varying factors (cap, ground, etc). You need to measure the Rl with an analyzer at the feedpoint w/o impedance matching (at resonance) using a 1:1 coupling transformer. Use the measured number as your denominator.

To get a more accurate Rr value, you either need to model the proposed antenna or use a more accurate calculator tool that allows for user-defined shape: RJELOOP1, KI6GD, etc.

For more insight and comments on the shortcomings of these calculators and even some equations used in the ARRL Handbook:

https://owenduffy.net/blog/?p=1693
https://owenduffy.net/blog/?p=1682

Also keep in mind that the simple loop will have a defined figure-8 pattern, with nulls perpendicular to the plane of the loop. So some thought is necessary on where you want to orient it. The nulls can be 6-12 dB or more down. I've done extensive testing between a 700ft circumference loop and misc verticals as references and have verified this in the field (as well as the efficiency being closer to 2-3% for that particular sized loop and environment).

73 Eric NO3M

Re: vlf antenna question
Posted by Eric NO3M on May 16, 2020 at 17:45:36.
In reply to Re: vlf antenna question posted by Eric NO3M on May 16, 2020

..... as a side note, the 700ft loop was about as good as a 1% efficient vertical in the directions of it's main lobes. The "vertical" was a Field Day 80m dipole up 45ft strung between trees used as a Marconi w/ the feedline shorted and only 10x 70ft radials.

In general, a loop will perform in it's peak directions about as good as a vertical with only 1/3 of the efficiency. Why? A large part of the loops radiation is also spraying at high angles... mostly useless.

Re: vlf antenna question
Posted by Eric NO3M on May 16, 2020 at 19:05:59.
In reply to vlf antenna question posted by James Fisher on May 15, 2020

getting back around to your question....

If you post your antenna dimensions: wire lengths on each side, height above ground, I would be happy to model it and give you the Rr.

After measuring the feedpoint resistance with an analyzer (start with a 1:1 xfmr of maybe 3 turns on the primary and secondary, FT-240-77 preferred, FT-240-75 maybe ok, or 3C90), then you'll have Rl.

A loop can be assumed to have a max theoretical gain of ~ 4.7dBi, or a gain factor (Ga) of 3 ( [10 ^ 0.47] * 10 ).

EIRP = TPO * (Rr / Rl ) * Ga

or if we re-arrange it to figure out the max power for 5W EIRP:

TPO = EIRP / Ga / Rr * Rl

example:

Rr = 0.03 ohms
Rl = 15 ohms
Ga = 3
TPO = 5 / 3 / 0.03 * 15 = 833 watts

Of course that is over the max allowed TPO of 500w, so with 500w:

EIRP = 500 * ( 0.03 / 15 ) * 3 = 3 watts

and the efficiency:

Eff = Rr / Rl = 0.03 / 15 = 0.002 = 0.2% which is quite realistic for a typical loop on this band.

Another reference: http://www.w1tag.com/Camp_Loop/Camp_Loop.htm

Eric NO3M

Re: HiFER shortage.
Posted by Ed Holland on May 18, 2020 at 17:50:55.
In reply to Re: HiFER shortage. posted by John Davis on May 13, 2020

Most amusing, John :). Perhaps it was me testing out the loop antenna made from a deep section bicycle rim, the Q is quite astounding, it might wipe out the watering hole for a few miles around...

This Saturday, May 16th, early evening (PST) looked a little better for Hifers. Noted signals included NC, 7P, possible WM and the WSPR from SIW. At least, it looks like WSPR, but I can never decode it.

Cheers

Ed

FlexRadio on Low Frequency?
Posted by Tim Brannon WA5MD on May 20, 2020 at 11:58:01.

I'm starting to get the new radio itch and been looking at the Flex-6400. There's not much on the Flex user forums about LF so I wondered if anyone here has used a Flex radio? I'd use it for general LF listening and 630m.
73, Tim WA5MD Dallas

Finding a Epson oscillator HiFER schematic
Posted by John K5MO on May 21, 2020 at 20:49:01.

I'm trying to revive BNC1 which has been off the air recently for a rebuild/repackage. I thought I used a schematic for the little circuit from here (looks like a 5V LDO and a 2n7000 buffer on the output)

Anyone recall this? It's been a year ++ since I put this together. This time I'll put a copy in my notebook.

Thanks
John K5MO

Re: "T" 13563.30 khz
Posted by John B in NC on May 22, 2020 at 00:23:46.
In reply to Re: "T" 13563.30 khz posted by Bill Hensel on April 30, 2020

Hi Bill,
Long time no chat. Good to know you're still sending out some low power RF

John

Re: Finding a Epson oscillator HiFER schematic
Posted by John Davis on May 22, 2020 at 06:23:09.
In reply to Finding a Epson oscillator HIfer schematic posted by John K5MO on May 21, 2020

Hi John. The only Epson schematic I'm aware of at this site is a design by KØLR which has been popular over the years. It doesn't use a 2N7000, though. The CMOS output of the Epson oscillator is already buffered and can output more than the required power with a 5 V supply. Some masochists insist on winding L1, L2, and L3 themselves on toroid cores, but the Digikey inductors in the parts list do just fine.

Re: FlexRadio on Low Frequency?
Posted by jim vm on May 22, 2020 at 16:40:04.
In reply to FlexRadio on Low Frequency? posted by Tim Brannon WA5MD on May 20, 2020

I find my Flex 6300 works FB on LF. I use the transverter port so as to not accidentally blow my Pixel Pro-1B loop antenna!

jim vm

EAR off the air
Posted by John Bruce McCreath on May 22, 2020 at 16:46:29.

Thanks to an e-mail from Garry, K3SIW, telling me that he couldn’t receive EAR,
I did some quick testing and found that it is indeed off the air! The problem is
with the TX itself, as a straight-key plugged into the exciter doesn’t produce
a signal. Further investigation is required. I’ll keep you posted.

73, J.B., VE3EAR

LowFER Beacon "EAR"
188.835 kHz. QRSS30
EN93dr

Re: EAR off the air
Posted by John Bruce McCreath on May 22, 2020 at 22:46:04.
In reply to EAR off the air posted by John Bruce McCreath on May 22, 2020

I did some testing this evening, and it seems that EAR is back on the air.
I suspect that it may have been a poor connection somewhere in the
signal chain, which I disturbed while doing the troubleshooting.

The ON7YD QRS keyer is operating correctly, the voltage and current
of the exciter and power amplifier are at the correct values, and the
RF ammeter indicates the correct value in the antenna system.

Reception reports would be appreciated, so I know it’s getting out of
my “back 40” of Aerial Acres! It’s solid copy on my DX-440 portable
receiver!

Tnx & 73, J.B., VE3EAR

Re: EAR off the air
Posted by Garry, K3SIW on May 23, 2020 at 00:29:30.
In reply to Re: EAR off the air posted by John Bruce McCreath on May 22, 2020

FB JB, I'm again copying EAR via ARGO at QRSS30 rate. I'm still not seeing WM at the watering hole although it is supposedly running normally. I wonder if the big storms we've had of late have had some impact. We got nearly 8 inches of rain in a couple days recently.

73, Garry, K3SIW, EN52ta, Elgin, IL

Re: EAR off the air
Posted by Mike N8OOU on May 23, 2020 at 01:01:57.
In reply to Re: EAR off the air posted by Garry, K3SIW on May 23, 2020

Garry,

You didn't mention when you looked, I did take WM down late this morning for 45 minutes or so. If you were looking in that time frame I would be missing. I have been checking frequently over the past couple weeks, and every thing looks normal on my end. All was good when I restarted it today.

Like JB, anyone with a report would be appreciated. My trees are now in full leaf so I wonder if any signal is getting off the property.

Mike N8OOU 73

Re: Finding a Epson oscillator HiFER schematic
Posted by John B on May 23, 2020 at 14:43:57.
In reply to Re: Finding a Epson oscillator HiFER schematic posted by John Davis on May 22, 2020

Thanks John, that looks like the article I referenced. I'll put my magnifiers on and see exactly what's there. I think I replaced the linear regulator with a lower power loss version and I'll have to look carefully at what else is there, but I'm pretty sure this is what I started with.

Amazingly, apart from the battery holder rusting apart, it all works even after being flooded with water for days and days and days (weeks?). I've got a few replacement parts on order (waterproof switch boots) and I'll put it back out again and see if anyone hears it. :-)

John K5MO

Notes on 16 May LowFER Net
Posted by Clint Turner on May 23, 2020 at 17:10:45.

Notes on 16 May, 2020 Lowfer net
(+/- 3929Khz Saturday morning 0800 California time)

Remember: You can participate virtually by listening to the WebSDR (KFS - go to http://69.27.184.62:8901/?tune=3929lsb +/- QRM ) and sending email comments during the net to Jerry via wa6owr@gmail.com

Present were:
Jerry, WA6OWR; Dave, WD4PLI; Ed, KI6R; Clint, KA7OEI; John, AEØCQ

Jerry:
• Still working on the MLA-30 active loop, replacing the original stainless loop using #8 copper wire and PVC.
• Planning to put the MLA-30 box inside a larger box on the pole - rotatable, at least initially, using the "Armstrong" method.
• Possibly use active whip as the noise source for active noise cancellation.

Ed:
• Running mobile, 90 watts at El Dorado Hills - good signal into KFS, S-9 direct to Jerry.
  • Visiting the house, keeping it and the yard nice-looking for showing during open houses.
• Using his newly-rebuilt screwdriver antenna.
• Not a lot to report from Arizona at the moment - will try to get on from there one of these days.

Dave:
• Been getting on 630 SSB almost every night with John, KK6GK.
• Randy is now on air on 630 meters with a modified HW-18
  • Has a 50 foot antenna - A "folded unipole", an aluminum mast with a wire that comes down to a metal patio roof - not sure of the precise arrangement.
  • He seems to be getting out OK - at least to Dave's QTH.
  • Using an older military variometer with taps for resonating the TX antenna - possibly a BC-306?
• Still considering what to do about inverter harmonics emanating from his Icom 7800 - send it in, or do work, himself?
  • (Note: Service manual may be found here: http://www.radiomanual.info/schemi/ICOM_HF/IC-7800_serv.pdf )
• Got a tube preamplifier for E-field whip to work:
  • Mostly to test the principles of using a "GlassFET" on an active E-field (whip) antenna working in the strong field with multiple AM broadcast stations.
  • Works from about 10 kHz to at least 80 meters - probably a bit higher.
  • Testing it in the yard so far, using it as a sense antenna for noise cancellation.
  • Been using the "potentiometer" trick to null noise.
  • Tried an ECC99 as a cascode follower - and then a "white" cascode follower using 102" whip - but got a bit of IMD.
    • Used a transformer to go from about 450 to 50 ohms.
  • Now using a 6AS7 octal - only one of the two triode sections being used.
    • No filtering involved: Seems able to handle the high E fields from the local mediumwave broadcast stations.
    • Tried as a follower and common-cathode - ended up using the latter as its plate impedance is pretty low - 250 to 300 ohms. Circuit designed for low gain as not much is needed.
    • Running it at about 50 milliamps at 150 volts.
    • Using a pot-core wideband transformer to go to 50 ohms, which is completely isolated.
    • Noted that the 6AS7 has a 8-10 pF input impedance - can start to "nibble" at the 70-ish pF capacitance of the whip portion which, depending on desired frequency range, may be a good reason why one might not wire both triodes in parallel.
    • Clint suggested ubiquitous (and still-produced) 6SN7 - lower plate dissipation, but otherwise roughly similar characteristics, less than half the input capacitance. (Would have to run lower current and/or voltage than Dave is running with the 6AS7.)
• Been blowing up Gali74+ MMICs on his loop, but they don't take any "nonsense" on the input/output, requiring protection in both places.
  • Had one for his broadband loop that worked well until it got blown up.
  • Considering making it a passive loop, instead - possibly using remote varactor tuning to resonate the loop.
  • Clint noted same issue - uses a four-diode full-wave bridge (with the +/- shorted) on the input, Zener on the output (6-9 volt) to offer protection, no IMD - capacitance low enough for HF use, but would reconsider for VHF/UHF.

Clint:
• Have been occasionally WSPRing on 2200 and 630 meters - fewer and fewer people are still monitoring as we move closer to summer.
• Wondered what tube Dave is using for his amplifier? Jokingly wondered if he's using a 4-400 to handle his high signal levels.
• Commented about the 2N5109 transistor not being made anymore - too bad, because it was relatively cheap and quite good in terms of linearity.
• Evaluating the use of BFU590GX RF transistor as a substitute.
  • $0.83 each in single quantities. Should be possible to use SOT-223-4 adapter board for through-hole applications - may need low value resistor (2-10 ohm) in series with base to keep it from breaking into song (parasitic oscillation.)
  • This is large-ish SMD transistor (made by NXP) with up to 2 watt dissipation and a P1dB of ≥21.5dBm.
  • 12 volt maximum collector-base voltage - lower than the 20-40 volt of the 2N5109, so it must be run at lower voltage.
  • Ft of 8.5 GHz versus the 2N5109's 1.3 GHz.
• Re: E-field whip amplifiers: Have constructed E-field whips for LF/MF using the Russian ΚΠ903 (KP903A) 6 watt JFET - seems quite durable and fairly low noise. May not be an ideal choice for upper HF owing to device capacitance.

John (via email and WebSDR):
• Another wet week, with a bit of sunshine.
• Another 25" of water accumulation for this year - 60% above normal. Been unseasonably cold - had a record low "high" temp.
  • Powerful storms Thursday/Friday
• Something odd happened - the electrician found the doors open to the building, but still locked; fortunately, nothing of value in the building.
• The "transfer switch" being installed - not a conventional one, but an interlocking set of breakers; the arrangement makes it impossible to back-feed the grid.
• Reference to QRSS logging:
  • Uses an old Acer laptop (not particularly fast) for logging as not much processing horsepower is required. (Argo and Spectran were usable on 80-100 MHz PCs many years ago.)
  • Uses 12 volt batteries to power laptop and receiver for backup-up.
  • In addition uses other laptops that were nearly "free", being cast-offs.
  • Added suitable ferrites on audio cables, etc. to minimize RF egress/ingress.
• Adding another LF and Part 15 newsletter to supplement the Lowdown - more timely information, references to topics of LowFER net.
• Would like to see a diagram/pictures of Dave's tube-type E field whip amplifier.
• Receive antenna at farm is a 40' vertical with 33 ground radials with lengths of 50 to 140 feet - vertical originally intended for 1750 meter TX.
  • Radio Shack mast sitting on PVC insulator pipe, underground coax (about 130')
  • At the base is an impedance-matching preamp using JFET and Bipolar transistors in a hybrid CFP arrangement.
• Antennas at the "town" shack - receive whip under construction, loop pending, but transmit antenna plans are still in the works - it will be a while before the ground is dry enough to do serious antenna work.
• Jokingly commented that a 3-500 triode might be better than a 4-400 in Dave's preamp. Likes this idea better than solid state; didn't want to zap an (increasingly) valuable 2N5109 and risk "bipolar disorder".

73,

Clint KA7OEI

Re: Finding a Epson oscillator HiFER schematic
Posted by WA1EDJ Bob on May 23, 2020 at 23:51:16.
In reply to Finding a Epson oscillator HiFER schematic posted by John K5MO on May 21, 2020

John,
I've got a schematic for a Epson programmable Osc HiFER TX that I got from Pat Bunn
N4LTA. It is the same as his USC HiFER TX. You can see a picture of it an issue or so back in the LOWDOWN. It is very nice and has adjustments for freq shift. I've built and used one myself.
If you want, I need to dig it out and I can send. I belive it is just the OSC and LPF output. No amps.

Bob EDJ

QRSSing on 10M currrently with WA1EDJ 28.125 850.
Not to detract from 22M but we sure could use some help on 10M QRSS.
I think there are more HiFERS than 10M QRSS stations!

Re: Finding a Epson oscillator HiFER schematic
Posted by john k5mo on May 24, 2020 at 00:35:56.
In reply to Re: Finding a Epson oscillator HiFER schematic posted by John B on May 23, 2020

Looked though what I built and the Fet is just the keying switch. I'm in the process of re=stuffing it into a better box (and hopefully more waterproof).

John

PS: Bob , I sent an mail direct, thanks!

WM Lowfer
Posted by Mike N8OOU on May 24, 2020 at 03:44:33.

WM Lowfer is off air to allow me to use its antenna on 630 meters. I will be testing a new loading coil and transmitter. I should have the Lowfer back on Sunday evening.

73 Mike

Notes on the May 23 LowFER net (+/- 3929Khz Sat 0800 California time)
Posted by Clint Turner on May 29, 2020 at 06:11:01.

Notes on 23 May, 2020 LowFER Net.

Remember: You can participate virtually by listening to the WebSDR (KFS - go to http://69.27.184.62:8901/?tune=3929lsb ± QRM ) and sending email comments during the net to Jerry via wa6owr@gmail.com

Present were: Jerry, WA6OWR; Dave, WD4PLI; Jim, WB6QZL; Clint, KA7OEI; John, AEØCQ

Jerry:
• Noted that the SDRPlay folks came out with Raspberry Pi software which allows the use of a remote server using the RSP.
  • Considering doing that from the top of the hill so he can be remote, in his shack - needs to make sure that everything is RF quiet and with enough power.
  • Perhaps deploy solar panels/battery to have it be self-powered.
• Have been playing with the MLA-30 - working well, at least as well as the active whip when in a quiet location.
• Comment about John's radial set-up - the more, the better, of course.
  • Years ago, when Jerry was setting up his "OWR" LowFER beacon in the country, he didn't have many radials at first - Operator "Z2" was able to hear, but it wasn't very strong.
  • After this there was, in Jerry's area, CATV hardline was being taken down and he was able to get large chunks of if for radials and that, along with replacing the military surplus tuning unit with a large, homebrew coil, greatly improved the signal, at least on par (if not louder than) Z2.
  • For a scout event, used an offset-center top-loaded wire and a dozen or so shorter radials - got out fine.
• Jerry suggested that it *may* be possible to connect to him via Zoom during the net so he can patch their audio onto the air - this, for people who live out of range of KFS and/or don't have a way to get on 75 meters.

Dave:
• Weather has been cool and rainy at time, but to be nice for the next few days.
• John, KK6GK is still in the learning curve, having recently gotten on 630 in QSO with Dave and Randy.
• Randy has continued to improve his antenna, signals coming up incrementally.
  • A big improvement was from barely readable to S9+ after burying a number of radials in the ground - as many has his wife would allow.
  • Randy uses a 50 foot vertical.
• KQ6RS - A 160 meter guy - saw signals on 630 on his spectrum scope and was able to get on the air from San Diego with low power and a poor match, but was just strong enough to be heard in the L.A. area. Dave didn't know what sort of TX gear he was using - perhaps a converter?
• John gave Dave an 813 tube - planning to make an amplifier that will cover 2200-160, input broadband and variometer-tuned output. Has 2kV plate and 10 amp filament transformer.
• A reminder that at around 9:00-9:30 PM local a group in the L.A. area gets on 476.0 kHz USB most nights.

Clint:
• Past day or so it's been cool and rainy in Utah - less antenna work than one might hope.
• Been running WSPR on 630 and 2200:
  • Still being heard with my 100-110 watts RF output on both bands: About 0.5 watts ERP on 630, probably about 0.05 watts ERP on 2200.
• A brief outage at the Northern Utah WebSDR last night:
  • One of the hams up north near the site - who also works for the ISP we use - was watching the lightning storm moving through with the leading edge of a strong weather front and saw it hit at/near one of their relays sites a few miles away, followed immediately by automatic notification and customer texts indicating that the site had gone offline.
  • He was able to get to the top of the mountain - after the lightning subsided - and was able to reset the equipment and repair minor damage, getting everything back online, returning home with himself and his vehicle covered with mud.
• Also at the Northern Utah WebSDR: The E-field whip for LF (<350 kHz) reception is on the same tower as the large beam roughly 150' away from the building - but the original feedline is gone.
  • Been using RG-6 on the ground, but it is repeatedly destroyed by the cattle that occasionally are in the acreage.
  • Working to borrow a trencher so we can drop several runs of coax (likely 1/2" CATV hardline) into the ground to help protect it from hooves and UV.

Jim (via email and WebSDR):
• Ordered QRP Labs beacon kit - hopes to put it on the HiFER band.

John (via email, audio file and WebSDR):
• Sent a few audio files to Jerry with his news/comments that Jerry played back so we could hear him "almost" real-time:
• Hoping for a dry day today to get more work at his station.
• Sent out some sample copies of the Flash newsletter
• Been 3 weeks since he's done organized listening - try some tonight, hoping thunderstorms hold off.
  • Planning to do a bit of HiFER listening after the net.
  • Look for WM during the day - see if propagation works as its groundwave.
  • Tonight - trying for EAR, which far enough that it is (pretty much) skywave only, except during the dead of winter during solar minimum when groundwave sometimes just makes it - something that happened for the first time this past winter.
  • Will also check 630 and 2200 meters to see if there's anything going on.
• Currently has 33 radials (50'-140') at the farm (similar plan for main LF antenna in town, whenever that happens). Originally did 16, then doubled it- and then started on several more, shorter radials - but didn't get more than that one just yet.

73,

Clint
KA7OEI

RY Off for Season
Posted by John, W1TAG on May 29, 2020 at 14:22:00.

Hifer RY in Raymond, ME is now off until the end of October.

John Andrews, W1TAG

Reminder: Lowfer net + or - 3929Khz Saturday morning 0800 California t
Posted by Jerry Parker on May 29, 2020 at 14:49:16.

Reminder: Lowfer net +/- 3929Khz Saturday morning 0800 California time

Or listen online at kfs:
http://69.27.184.62:8901/?tune=3929lsb
or
KPH Point Reyes:
http://198.40.45.23:8073/
or
Utah Web sdr:
http://www.sdrutah.org/websdr1.htmlIf 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,
Jerry WA6OWR

Re: RY Off for Season
Posted by John Davis on May 30, 2020 at 05:06:49.
In reply to RY Off for Season posted by John, W1TAG on May 29, 2020

I shall again miss my most reliable frequency reference for the summer.

This was my best capture of RY last weekend. It was just over an hour after sunset last Saturday, and NC had drifted to less than 2 Hz above something that may or may not have been PVC, while EH had positioned itself so that its mark frequency was right square atop 7P. MTI was faintly visible a few seconds after 9:34 and 9:36 PM CDT.

Shortly after, EH went away and so did the maybe-PVC signal. By an hour later, only NC, sometimes 7P and sometimes MTI remained visible. NC was the last to go, shortly after 11 PM if I recall correctly. But none of those quite matched RY at its peak.

John D

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  File Attachment 1: 23may0040.jpg

Watering Hole/Black Hole
Posted by John Davis on May 31, 2020 at 05:31:03.

I tried for LowFER WM this evening, but suspect it must still be off. Nobody else around either, per their published schedules, so I finally gave up a little before midnight and went to 2200 m WSPR. So far, only WH2XND, but I'll be optimistic and stay tuned there through the rest of the night, just in case.

New HiFER, or old mystery beacon P with a new ident?
Posted by John Davis on May 31, 2020 at 06:31:43.

Loud slow CW identifying "F" on ~13555.065 nearly an hour after sunset tonight. I recorded several minutes of it all alone (no WV at that time) before resuming my band scan. An audio clip is attached, containing four repetitions very close to 9:30 PM CDT, with a few click-clicks from codar audible too. Screen captures will be posted Sunday.

Before finding F, the watering hole contained only PVC (now down close to 13555.480) and 7P, with a sudden five minutes of solid WM from just before 9:20 to just before 9:25 PM. The CW ID just after 9:22 was clearly audible.

(Right before that, SIW slant faded out. It had been present in varying degrees since about 4 PM. SIW WSPR appeared a few times in the first half hour after sunset, but I wasn't watching in person right then and neglected to start the decoder. That was about the same time EH faded out--it had been strong all afternoon, and had wandered right between PVC and 7P, wiping them both out until it retired for the night. NC was fair earlier around 13555.460, but faded right at sunset.)

After 9:33 PM CDT, I tuned down from F and caught AZ faintly for a few minutes. Above the band center, only VAN and FRC made it through. VAN's DAID hooks were visible for a while before the keying became visible and faintly audible just before 9:41 PM. K6FRC eluded me for a couple of minutes, but then rose to fair audibility with some QSB. No JUN, WAS, ODX or ABBY, either during the afternoon nor this evening.

At 9:51 I returned to 13555 and had fair to good copy of WV for five or six minutes, with F absent at first, but gradually fading back in to clear audibility.

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  File Attachment 1: F.mp3

Re: Watering Hole/Black Hole
Posted by Mike N8OOU on May 31, 2020 at 18:44:50.
In reply to Watering Hole/Black Hole posted by John Davis on May 31, 2020

John;

Lowfer WM is on the air. I took an extra day on 630 to try to resolve an issue with RFI causing the exciter uP to lock up. That's a work still in progress.

Anyway, WM has been up for a few days. I re-tuned the LF loading coil after swapping out the MF coil. I checked all my instrumentation this morning after reading your message. Everything on my end reads the same as this past winter, and when I restarted a few days ago.

I know Garry has not seen WM for a while, I have not heard from him since I restarted WM. The only variables left in play are under control of mother nature. Ground moisture, Tree Leaves, and Propagation Conditions.

It will be several weeks before I will be able to attempt 630 again. Until then, I will keep both part 15 beacons warming the ether.

Mike N8OOU 73

WM Lowfer Capture
Posted by Mike N8OOU on May 31, 2020 at 19:49:37.

All;

I am not intending to toot my own horn here, This is an explanation of how I check the operation of my Lowfer.

Located about 100 miles East of me in Edinburg In. is a KiwiSDR that uses a good LF/MF antenna. You can go to Kiwisdr.com/public and use "Edinburg" as the search term to get the link to this radio.

Once there, I set the frequency to 184000 USB then start Argo in a new window. I set the Argo Calibration to 184000, QRSS30 mode, Set in MY call and Loc. I use Linux and the PulseAudio functions to redirect the audio from my browser to Argo. Argo must be started first.

I am not a Windows expert, but the browser audio can be redirect to Argo using Virtual Audio Cable software.

That receiver is good for monitoring All of the LF and MF signals. It can pick up my lowfer almost any time day or night. I have put up a capture I made this afternoon on my website;

http://n8oou.meekfarm.us//ArgoCaptures/WMLowferMay312020.jpg

Mike N8OOU 73

Re: WANTED - users of Bendix DU Loop Antennas
Posted by Kevin Carey on May 31, 2020 at 20:04:59.
In reply to WANTED - users of Bendix DU Loop Antennas posted by Joe Long / WA2EJT on May 06, 2020

Joe, I will post a request in The LOWDOWN journal coming out soon. I have found that a good number of folks on this page are not LWCA members, and therefore it will open up your request to a wider audience. 73, and good to work you on the air earlier today!

--Kevin

www.lwca.org

potrzebie