NJDTechnologies

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Current Operating Frequency and Mode

OFF AIR but hope to be back by 1115z Saturday morning if I don't oversleep

Session not quite as robust as the previous for many reports but not a bad night in spite of QRN and decreased geomagnetic conditions; Great openings between Oceania and Asia; Beware of Internet rumors about fake UTC notification procedures!; Field day outreach opportunity station sign up in progress; Big night for VK -> JA path; W5EST presents ‘Try a Top-Fed Inverted Delta TX Antenna on 630m?’

– Posted in: 630 Meter Daily Reports, 630 Meters

The details for June 13, 2016 can be viewed here.

IMPORTANT REMINDER: Neither 630-meters nor 2200-meters are open to amateurs in the US yet.  Please continue to be patient and let the FCC finish their processes.  Click here to view the proposed “considerate operators” frequency usage guide for 630-meters under Part-97 rules that was developed with the input of active band users.

There is a rumor that has been circulated somewhere on the Internet that claims to allegedly know the UTC notification procedures.  These rumors are lies and seriously jeopardize this process! DO NOT CONTACT UTC TO NOTIFY THEM OF YOUR INTENT TO OPERATE on 472 or 137 AT THIS TIME!  Official procedures are forthcoming – please be patient.  If you find a website or social media post that is perpetuating this bad information, please let me know so action can be taken to rectify the problem.  We can still screw this up!

QRN was a bit more active during this session as storms flared-up for a second night in the north-central US.  Evening storms were present in the gulf coast region as well as Mexico and Alberta, Canada.  Propagation was probably average but lacking some of the robust high-latitude trans-Pacific openings of the previous session.  The path between Oceania and Asia was very good, however.

11-hour North American lightning summary

 

Geomagnetic conditions were more active during this session with Kp values at elevated-quiet levels.  The Bz has been variable but generally pointing to the South and solar wind velocities have been  elevated above 500 km/s for much of the session.  DST values have been impacted by the solar wind activity and have pushed into negative levels.

 

 

 

John, WA3ETD / WG2XKA, has finally dried out and re-tuned his system and he provided these comments and statistics:

“WG2XKA finally managed a full session following an extended period of very wet weather.  Noise levels remain high due to storms north and east of me.  XKAwas heard by 17 and heard 7.”

WG2XKA session WSPR activity (courtesy WA3ETD)

 

Ken, K5DNL / WG2XXM, provided reports for five WSPR stations and he received reports from 32 unique stations including WH2XCR, ZF1EJ and four Canadian stations.

Rick, W7RNB / WI2XJQ, provided reports for seven WSPR stations and he received reports from thirteen unique stations.  Rick’s unique report details can be viewed here.

Larry, W7IUV / WH2XGP, provided reports for six WSPR stations and he received reports from 21 unique stations.  Larry indicates that the coax for his West-facing receive antenna that is normally designated as W7IUV became disconnected from the SDR so he had no reports for that receiver / antenna combination.

WH2XGP session WSPR activity (courtesy NI7J)

 

Al, WD4AHB, reported that “Here in Florida we’re really catching up on our lack of rain earlier this year. Last night’s session QRN at my location was low enough to yield pretty good results with 8 unique spots. I’m back to using my homebrew PA0RDT design active mini-whip; it has a bit of an edge over the other designs I’ve used.”

WD4AHB session WSPR activity (courtesy WD4AHB)

 

 

Neil, W0YSE/7 / WG2XSV, reported that he “…was RX only last night as I tried to compare a new loop in the attic with my vertical. Here is the result of the loop:

The loop is 3 turns that are each about 12 ft long by 5 ft high and tuned with about 1100 pF. There is a smaller single turn pickup loop (inside of the tuned loop) for the coax feed line. I assume the pattern is E-W since the loops orientation is E-W, but with all of the house wiring, who knows…

The computer on the vertical system had a lock up with WSPR and it stopped working right after I went to bed, so no results yet on comparing the two antennas.

I spotted Ken/XXM in OK 26x with a best of -17. I got only 1 spot of Merv/XCR in HI at -26 as seen above.

I got 77 spots of Ward/XXP in AZ with a best of +1, and several other from -2 to 0 at the following times:

I am please so far with the fact that a loop in my attic even works at all and I will be continuing to experiment with it.”

 

Trans-Pacific report detail, excluding KL7 and KH6, can be viewed here.

Hideo, JH3XCU, provided this link detailing VK -> total JA DX and VK -> JA peak S/N for the session.

Roger, VK4YB, reported that “QRN is rather high and more persistent than yesterday. The path to Hawaii is down by about 8dB compared to normal.  John, VK2XGJ had a good run with WH2XXP earlier but no trace of Ward at my QTH.  I gave up with N America at 12:16z and changed to the JA beam with an immediate response from JA1NQI/2.   I was so surprised to see Ward come through at 12:24 at -27dB off the side of the JA beam. That was a sunrise enhancement par excellence.  VK8RR was on 30m not 630m.”  Roger received reports from 7L1RLL, JA1NQI/2, JA3RVF, JA8SCD5, and TNUKJPM.

John, VK2XGJ, reported that WSPR decodes began at his station at sunset:

VK2XGJ WSPR console

 

Ward, K7PO / WH2XXP, received reports from 35 unique stations including VK4YB and VK2XGJ.

WH2XXP session WSPR activity (courtesy NI7J)

 

As daylight gets longer for a few more weeks, I am starting my activities later each evening.  I started out with CW on the approach to sunset at the request of a station to the South that has been evaluating receive capabilities during the day / night transitional period.  We know from AM radio that the change can be pretty remarkable due to instabilities and “tilt” in the ionosphere.  All of these details should be released in the future.  I had no additional QSO’s but the “phantom ditter” may have made a brief appearance.  At 0222z I transitioned to WSPR for the night and immediately received reports from the Southeast and parts of the Midwest.  The band sounded a bit noisy and evening lightning reports suggest quite a bit of activity.  My transmission reports can be viewed here and were quite balanced with my reception reports, which can be viewed here.

WG2XIQ 24-hour WSPR activity

 

Details and updates for the 2017 ARRL field day outreach and demonstration opportunity can be viewed here.  Here is a list of the current participants and their details:

Regional and continental WSPR breakdowns follow:

North American 24-hour WSPR activity

 

European 24-hour WSPR activity

 

Japanese 24-hour WSPR activity

 

Oceania 24-hour WSPR activity

 

Eden, ZF1EJ, provided reports for five WSPR stations and he received reports from seven unique stations including WH2XCR.

ZF1EJ 24-hour WSPR activity

 

Merv, K9FD/KH6 / WH2XCR, provided reports for ZF1EJ and shared two-way reports with VK4YB.  He received reports from VK2XGJ.  The lead up to sunrise in KH6 was uncharacteristically slow during this session.  DX report details can be viewed here.

WH2XCR 24-hour WSPR activity

 

Jim, W5EST, presents, “TRY A TOP-FED INVERTED DELTA TX ANTENNA ON 630M?”:

“Lately, I’ve been modeling a “▼-shaped” inverted delta TX antenna geometry to multiply antenna current and that way increase radiation efficiency on 630m. This could provide operators with greater flexibility in choosing transmitter designs and/or sizing a TX antenna for available real estate.

To prepare for modeling an inverted delta, and since ground resistance is a large component of LF/MF antenna efficiency, I first used EZ-NEC on a very different antenna geometry to model Roger VK4YB’s  “bottom hat” antenna from the May 31 blog, http://njdtechnologies.net/053117/ I found that EZ-NEC fitted to Roger’s blogged 50Ω antenna data if I entered a low-value 3.3mS/m real ground conductivity. (…whether or not that’s really what Roger’s system has for ground!)  For a tutorial on EZ-NEC, see http://njdtechnologies.net/042516/

I considered a 70′ high top fed design with at least twice the current circulating in the inverted delta versus current entering it.  My trial-and-error EZ-NEC solution settled on three reactances: 300 uH variometer fed by coax from transmitter TX,  440 pF outdoor capacitance at bottom of one delta leg, and 63 uH at bottom of other delta leg. I allowed 4 ohms in the model for the variometer ohmic resistance at 475 KHz.  The outdoor capacitance should be carefully tuned to resonate in center of 630m band.  The modeling plotted SNR variation across 472-479 KHz which suggests moderately high Q.  Since wind might disturb the antenna and vary the resonant frequency, an implementation should be supported well enough to keep the antenna from inadvertently detuning.

I specified #12 copper wire and the same 3.3 mS/m ground conductivity value and aimed for an inverted delta antenna design that would present 50Ω impedance as tuned.  Stations having other ground conductivities would tune the reactances differently and might add an RF transformer between the TX and the ATU to match to 50Ω.

Since another ground resistance value would alter any particular antenna system efficiency number, I compare the inverted delta efficiency with a top hatted vertical having similar ground conductivity.

The first two illustrations indicate this 70′ high top fed inverted delta has about 2.4 ohms radiation resistance for favorable 4.87% efficiency (radiated power divided by TPO) based on the EZ-NEC results with the 3.3mS/m ground. This way, 48 watts TPO would deliver about 2.4 watts total radiated power, and 4.07w EIRP (36.1dBm EIRP = 46.8 dBm TPO – 15.33 dBref + 4.6 dBref/isotropic in 1st illustration). In the lossy antenna, ground is 3.3 mS/m, all wires are #12 copper, and I budgeted 4 ohms to the variometer.

The 2nd illustration employs one EZ-NEC way of telling antenna efficiency: I set variometer resistance to zero, copper wire loss to zero, and ground to “Perfect.” That leaves radiation 2.337W lossless/ 48.01 total watts to lossy antenna = 4.87% inverted 70′ delta efficiency.  At 4.19 dBi the lossless model antenna has a fat pattern which is ok on 630m. Compare the electrically short monopole’s 4.77 dBi:  http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwiXkOHe4rjUAhUM-2MKHcslANMQFggiMAA&url=http%3A%2F%2Fwww.500kc.com%2Fdownloads%2FRN06-32.pdf&usg=AFQjCNFaVIa8HM6wxSpPG7BvSSxkJsfgcg

For its size, the modeled inverted delta physical dimensions are compact: 70′ high, 100′ wide and slant feed from TX out 50′ and 70′ up to delta center. If 48 watts TPO injects 1.0A RF current to drive the system, the resonated inverted delta has about 2.4A RF current circulating anti-phase in it.  Some unpreferred reactance combinations by contrast might have in-phase currents running down the inverted delta legs, or most current going down one leg. Instead, the radiation efficiency is made much greater by establishing nearly-equal anti-phase currents to circulate around the inverted delta.

In the 3rd illustration for comparison, I ran EZ-NEC specifying a 73′ tall vertical 1.5” copper tube on 4 mS/m ground and having a 200′ top hat of #12 copper wire centered on top.  Loading inductance came out 195 uH for it, and I made its loading coil resistance zero ohms.

Illustration #4 losslessly analyzes this 73′ vertical x 200′ top hat. The numbers come out 1.45 W lossless / 61.08 total watts to lossy vertical = 2.37% top hatted vertical efficiency.  Lossy top hatted vertical has 4 mS/m ground conductivity (specified that way to get favorable SWR), #12 copper wire top hat over 1.5″ vertical tube, and zero ohms in 195 uH loading coil. For lossy vertical model, EIRP = 2.7 watts or 34.3dBm = 47.86 dBm TPO -18.73dBref + 5.19 ref over isotropic. For lossless vertical model, EIRP = 4.35 watts or 31.614 dBm -0.42 dBref + 5.19 dBref/isotropic = 36.384 dBm.

Efficiency ratio of lossy inverted delta to lossy top-hatted vertical is 1.92x, or 2.83dB [4.07wEIRP/48.01wTPO] / [2.7wEIRP/61.08wTPO] .  This says the lossy inverted delta is almost twice as efficient and can offer us considerable 630m design flexibility.

Illustration #5 indicates the azimuth pattern of the inverted delta is essentially omnidirectional. In tandem with Illustration #1, the elevation pattern has a 20dB zenith null in one azimuth direction and 7dB zenith null in a 90 degree azimuth direction. Its pattern is somewhat fatter than for a vertical, and the pattern bulges down for low angle transmission.

Physical support to hang the inverted delta should prove practical since 630m people do also successfully hang long top hats for verticals. Grounding would call for a TX earth ground and a ground 50′ away to return both reactive loads, 440 pF and the 63 uH, via earth. I picture straightforward ground rod earth grounding and/or with an optional modest radial field. The model’s 50 ohm match includes “real ground” conductivity.

RF voltage safety would call for the usual management. Not only would the 300 uH variometer have about 1KV rms of RF on its up-slanted lead, but also the HV top of the inverted delta would lead down on two sides to its inductance and capacitance.  Roughly 2 KV rms, 2.8 KV peak RF voltage might occur there.

In summary, the inverted delta’s principle of operation expects high resonant RF current uniformly distributed up the delta height. The MF transmitter TX feeds the high impedance top center of the parallel LC circuit of the delta for favorable SWR when the reactance is tuned out by the TX variometer. Does a 1920s vintage article or patent show it and give more information? This MF top-fed, bottom-loaded geometry certainly differs from a conventional HF bottom-fed delta loop of: http://www.dxzone.com/dx31569/40-10-delta-loop-antenna.html

Modeling suggests today’s illustrated inverted delta works like putting an LC “supercharger” on a top hatted slanted vertical. As modeled, the inverted delta acts like two slant verticals to 70′ operating in push-pull and sharing the 100′ top wire like a “shared top hat.”

Since modeling is treacherous, one can only wait and hope such an antenna has been or will be constructed and tested to see if it indeed performs as the model advertises.

Tell us a good reference or more information from your experience, by e-mailing to  mrsocion@aol.com .  TU & GL!”

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Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD gmail dot (com)!