NJDTechnologies

Radio: it's not just a hobby, it's a way of life

Current Operating Frequency and Mode

OFF AIR but will be QRV on CW somewhere between 472.5 kHz and 475 kHz after dark

SCHEDULED ACTIVITY: CQ 474.5 kHz CW by 1030z through sunrise most days, WX permitting

Geomagnetic storm yields a challenging session but a few trans-Atlantic and trans-Pacific reports are received; WG2XSV persistent daytime reports at VE7SL; ZF1EJ and ZF1RC report WH2XCR; VK3ELV –> VE7SL

– Posted in: 630 Meter Daily Reports, 630 Meters

The forecast geomagnetic storm arrived during the day on Saturday resulting in diving magnetometer values and increasing solar wind velocities.  Propagation during the day was above average for some, however.  Neil, W0YSE/7 / WG2XSV, reported that his 200 mW was observed by Steve, VE7SL, at noon:

WG2XSV VE7SL 040316

WG2XSV, as reported during the day by VE7SL

 

This morning Neil provided additional details about the session and his complete session raw dataset:

WG2XSV 040316

 

Neil went on to report that during the session he decoded five WSPR stations and was decoded by ten unique WSPR stations.  Not bad at all and its a bonus at 200 mW!

Eric, NO3M / WG2XJM, called CQ for a bit during the North America evening on 474.5 kHz CW, as I had also done a few minutes earlier but there was no copy in either direction.  Mark, WA9ETW, reported that he was hearing Eric at RST569 – 579.  WSPR reports for Eric yielded levels outside of the normal -10 dB S/N required for comfortable aural CW reception.

The geomagnetic field has begun to calm down and solar wind velocities are below 500 km/s.

planetary-k-index 040316

 

Kyoto DST 040316

 

Australia 040316

 

Phil, VE3CIQ, reports that he decoded six stations using an E-probe and was decoded by seventeen unique WSPR stations through the session.

VE3CIQ 040316

VE3CIQ session WSPR activity

 

Joe, DF2JP, reported that he operated DFCW3 at 2mW on 476.190 kHz.  Its unknown whether he received any reports.

Steve, VE7SL, reports that he decoded eight WSPR stations, including Phil, VK3ELV.

VK3ELV VE7SL 040316

VK3ELV, as reported by VE7SL

 

Ken, K5DNL / WG2XXM, reports that he decoded eight WSPR stations and was decoded by 42 unique stations during the session, including VK4YB, and VK2DDI.

WG2XXM VK4YB 040316

WG2XXM, as reported by VK4YB

 

WG2XXM VK2DDI 040316

WG2XXM, as reported by VK2DDI

 

David, VK2DDI, provided this screen capture showing WH2XCR, WG2XXM, and other VK stations:

VK2DDI 040316

VK2DDI WSPR console

 

Larry, W7IUV / WH2XGP, reports that he decoded seven WSPR stations and was decoded by 33 unique stations during the session, including VK4YB, and VK2DDI.

WH2XGP VK2DDI 040316

WH2XGP, as reported by VK2DDI

 

WH2XGP VK4YB 040316

WH2XGP, as reported by VK4YB

 

Mike, WA3TTS, provided this report and statistics from snowy Pittsburgh:

WA3TTS 040316

 

WSPR activity was high with 85 MF WSPR stations observed on the WSPRnet activity page during the evening in North America.  KJ6WSM was reported as a new receive station during this session.  Welcome aboard!

Regional and continental WSPR breakdowns follow:

NA 040316

North American 24-hour WSPR activity

 

EU 040316

European 24-hour WSPR activity

 

VK 040316

Australian 24-hour WSPR activity

 

JA 040316

Japanese 24-hour WSPR activity

 

There were no reports from the trans-African path.  UA0SNV was present from Asiatic Russia but no reports were observed in the WSPRnet database.

The trans-Atlantic path was limited to reports by WD2XSH/17 ok DK7FC.

DK7FC WD2XSH17 040316

DK7FC, as reported by WD2XSH/17

 

In the Caribbean, Eden, ZF1EJ, and Roger, ZF1RC, both reported WH2XCR in Hawaii:

ZF1RC 040316

ZF1RC 24-hour WSPR activity

 

WH2XCR ZF1RC 040316

WH2XCR, as reported by ZF1RC

 

ZF1EJ 040316

ZF1EJ 24-hour WSPR activity

 

WH2XCR ZF1EJ 040316

WH2XCR, as reported by ZF1EJ

 

In Alaska, Laurence, KL7L / WE2XPQ, was only receiving through this session, decoding a few stations in the western US plus Hawaii in spite of the geomagnetic storming conditions.

WE2XPQ 040316

WE2XPQ 24-hour WSPR activity

 

WH2XCR WE2XPQ 040316

WH2XCR, as reported by WE2XPQ

 

In Hawaii, Merv, K9FD/KH6 / WH2XCR, experienced two-way reports with VK3ELV and VK4YB.  ZF1RC and ZF1EJ both provided multiple reports for Merv during the session and the path into the north eastern portions of the US was also open.

WH2XCR 040316

WH2XCR 24-hour WSPR activity

 

WH2XCR VK4YB 040316

WH2XCR, as reported by VK4YB

 

WH2XCR VK3ELV 040316

WH2XCR, as reported by VK3ELV

 

WH2XCR VK2XGJ 040316

WH2XCR, as reported by VK2XGJ

 

WH2XCR VK2DDI 040316

WH2XCR, as reported by VK2DDI

 

In Australia, Phil, VK3ELV, and Roger, VK4YB, experience two-way reports with WH2XCR.  Phil was also reported by Steve, VE7SL, as previously reported.  There were no additional JA reports for Phil at the time of this report preparation.

VK4YB WH2XCR 040316

VK4YB, as reported by WH2XCR

 

VK3ELV WH2XCR 040316

VK3ELV, as reported by WH2XCR

 

Jim, W5EST, provided the following discussion entitled, “MF/LF TOP HATS AND DEGREE-AMPS”:

“Today, let’s talk about the advantages and disadvantages that MF/LF top hats can deliver.

Top Hat Advantages:

Higher EIRP comes from a more nearly uniform current distribution all the way up a TX vertical. https://en.wikipedia.org/wiki/T-antenna . But remember that adding top hat doesn’t help you if your license is subject to a legal limit EIRP that’s reached by your station already.

A vertical without a top hat has no current at its tip, meaning the upper part of a hatless vertical is inefficiently used.  Average RF current for a hatless short vertical is only half what an RF ammeter shows at the antenna base.  Top hat lets a shorter vertical antenna yield same total radiated power TRP by increasing its degree-amperes, as discussed March 31, this blog.

2 amperes of 630m RF base current in a 10° tall hatless short vertical can give 10 degree-amps (2 x ½ x 10°) and yield 15 degree-amps with an ample top hat.  A top hat can increase average RF current by about a quarter to half, which could as much as double the TRP.

Top hat increases antenna system capacitance. You get more flexible QSY by decreasing the system Q.  SWR increases rapidly as your frequency departs from antenna system resonance, see graph Feb. 10, this blog. With lower system Q the SWR doesn’t increase so rapidly. Then you can QSY temporarily a little way without retuning or by just retuning a little in the shack instead of outdoors at the ATU.

Decreased Q somewhat lowers antenna voltage KV from antenna base to top hat. On 630m Q = (2π 475)L/R by definition and Vantenna = 1.4 Q  P / I  <  Vbreakdown.  See Jan. 16, this blog.

Top hat wires can be symmetrically or asymmetrically positioned to give approximately similar capacitance whichever way.   I’ve not modeled the effect of a top hat on the azimuth and elevation antenna patterns of an electrically short vertical.  I don’t think the effect is very significant. But if you know a link or some better information about this, let us know.

If your radials have extended way beyond the extent of a small top hat high above, then providing longer top hat conductors above the radials can more efficiently utilize the radials.   If the radials mostly go in one or two directions, then for highest antenna system capacitance the hat wires should extend in those directions to couple best with the radials.  Your experience may suggest this last is not too important, especially if you have a perimeter conductor and/or several ground rods and your soil has favorable conductance.

Another top hat advantage is that top hat conductors are compatible with structural support and stabilization for the very top of an MF/LF vertical antenna.  You get added degree-amperes–and steadying at the top to boot.

If the top hat slants upward, its system capacitance contribution is somewhat decreased compared to a top hat of same length horizontally, but the vertical slant contributes radiated power. Depending on the arrangement of antenna and trees on some properties, using a shorter vertical with an upwardly slanting asymmetrical top hat may make the antenna system both easier to guy and less obvious to neighbors.

Putting in a top hat or improving a top hat increases the degree-amperes of a short vertical mainly by distributing the same RF amperes more uniformly.  Adding more radials and longer radials decreases the antenna system resistance and increases the degree-amperes of a short vertical mainly by increasing the RF amperes of antenna current itself.

Top Hat Disadvantages:

A top hat obviously requires outdoor work to construct or revise it.  You may be able to simply increase your transmitter power TPO more conveniently than to do the outdoor work.

A top hat needs to extend more or less horizontally from the top of the vertical, although the angle is not too critical within +/-45°.  Distant supports for the top hat at that top level may be unavailable or expensive and inconvenient to provide. If the top hat were attached to the vertical below the top of the vertical, the otherwise radiation-beneficial top segment of the vertical becomes mostly unused.

If the top hat slants quite steeply downward, its effect on system capacitance may be a wash– more capacitance by closer approach to the ground and less capacitance because same length top hat conductor extends less outward over the ground below. That defeats a reason for putting up a top hat in the first place.

Moreover, if the top hat slants steeply downward, then vertically downward RF current in the top hat cancels part of the radiation from the vertical antenna and at least partially defeats the improvement in vertical antenna current uniformity that the top hat is intended to confer.

A long top hat may not fit on the available real estate.  Even if it fits, it may add to visibility as far as difficult neighbors are concerned.

Adding a top hat means you need to retune the ATU after the addition. But so does improving the radials or just about anything else you do.

Top hat conductors add more weight on a vertical than lighter-weight guying does.  The weight of the top hat likely adds to the support demanded of the antenna base.  If you put downward-slanting top hat conductors under tension at their far ends to keep them from drooping in the middle, then a lot of that tension will be imposed on the vertical too.   That can produce a buckling force on the vertical which may call for additional guying halfway up the vertical.

Top hat conductors convey a declining but substantial RF current along their length.  That involves I2R losses in the skin effect resistance of the top hat conductors. However, if your earth resistance is high or your radial/grounding system is not very elaborate, some loss in the top hat probably does not decrease the RF amperes of antenna base current very much at a given TPO compared to the improvement in radiation TRP that the top hat gives you.

If skin effect resistance losses in the top hat are significant compared other losses in the system, reducing top hat losses generally means more conductors or heavier conductors in the top hat.  That translates to more weight for the whole system to support.

A top hat translates KV of antenna top voltage to its ends. If the top hat extends all the way to leaf cover of trees or shrubs, unexpected sparks might jump to them in quiet weather, or in windy weather, or sometime when such trees or shrubs grow nearer to the top hat end(s).

Generally top hat advantages outweigh their disadvantages so long as you plan intelligently. Please tell us your experiences with top hat advantages and disadvantages!”

 

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