Saturday, 21 July 2018

6m ... Where'd The Magic Go?


This summer's 6m sporadic-E (Es) DX season is now well past the half-way mark and things have been different ... a lot different. For me, the past 40 plus summers of activity on the magic band have always been interesting, if not down right exciting ... particularly when the band opens to Europe from the west coast.



These usually very short-lived paths have been my main interest for the past several years and the bread and butter mode is normally a fast CW exchange, usually taking less than 20 seconds before signals would vanish, as the always quirky west coast path to Europe would jump to another region. But this has all changed dramatically.

As well, it seems that this summer, the normal SSB and CW modes have been largely abandoned by a huge percentage of the crowd, in favor of FT8, the weak-signal digital QSO mode originally developed with 6m in mind.

I have seen many strong openings involving loud FT8 signals from various parts of North America but when tuning down to the CW/SSB section of the band, found nothing but ghostly silence! Gone are the familiar voices of friends met every summer for decades or the recognition of an old friend's fist on CW ... for me personally, most of the magic was missing this summer. I wonder if this is all part of the natural evolution of amateur radio or does the FT8 revolution signal the long term fate for many of the older conventional modes?

There appears to be a lot of new activity brought to the band by this mode, and many are experiencing the magic band for the first time. I have heard at least two dozen or more VE7 calls on 6m this summer that I have never heard before and this is a very positive thing! From what I can tell, many of the new stations on the band may have makeshift or simple antennas, such as verticals or dipoles and not something larger and are just getting their feet wet on the band.

FT8 allows for two-way weak signal work (a few db below audible limits) that the traditional modes would not support, and simpler stations, without big antennas, can now join the fun. I often see many of the newer stations calling CQ but not hearing their numerous replies, which leads me to think that their receive-capability does not yet match their transmit-erp ... perhaps they just have a lot of local noise or are running more power than they can properly deal with, something they should think about. Often the new FT8 stations will continually CQ, sometimes as long as 90 minutes at a time and create a lot of unnecessary and waterfall obliterating QRM on the band for those that do have good antennas and can hear what they do not. I'll do another blog later regarding FT8 on 6m, and what I have observed this summer.

Here on the west coast, up until last summer, it was fairly normal to have a few short-lived Es openings to Europe. You had to always be on your toes to catch these as they would vanish as suddenly as they appeared. The best of these was back in June of 2012 when a mid-morning opening produced 31 CW contacts in DL, F, SP, CT, ON, GM, IT, LZ, EI, G, S5, I and EA8. Nine new countries were put in the log that morning as the Es clouds danced around, shifting the propagation from one country to another, every other minute. This was the magic band at its best!

Like last summer, this year has produced almost zero trans-Atlantic propagation from VE7 land, other than contacts with CT1 and EA8, both on FT8. Perhaps some external factors are changing the band enough that this path will vanish permanently ... only time will tell. 
Dave, K7RWT, recently pondered if it may have something to do with the north magnetic pole migration over the past several years as it moves to the north-northwest at ~60km per year.

Track the pole's movement here.
Most mornings, the Europeans are into the east coast early, often times making into the central states and occasionally into the southwestern states:

July 18th courtesy: http://www.on4kst.org/chat/index.php
Later in the afternoon, it has not been unusual to see widespread JA to North America action, usually going straight overhead and as far back as the New England states and down to Florida!

July 20th courtesy: http://www.on4kst.org/chat/index.php

There have been several openings between here and JA, sometimes lasting for several hours. So far I've worked about 200 JAs this summer and judging by the flood of daily QSLs arriving from Japan, many are newcomers to the band (the FT8 effect?), often indicating that I was their 'first VE' contact on 6m.



Unlike the west coast to Europe openings, the JA-NA path appears to be growing, this summer particularly ... perhaps it's just those extra few db provided by FT8 that is responsible.

One particularly interesting 'opening' from here happened in the wee hours, starting just after 2300 local time and ending just after 0200, as all west coast operators were sawing logs. A morning check of my FT8 decodes indicated many strong signals from Japan, Taiwan, China, Korea and Hong Kong. I'm sorry that I missed out as the VR2 would have been a new country for me.

Overnight decodes July 8-9
 The non-JA stations heard were:

BM6GJL PL02
HL1BRU PM37
HL2IFR PM37
BG4QNE PM01
VR2VAZ OL72
BV2FB PL05
BV6CC PL03 

BV1EK PL05
BM3GFU PL04


Thanks to Paul, K7CW, for doggedly sorting through my all-night decode file which may be viewed in full here.

With just a couple of weeks left in the normal Es season, it will be interesting to see if FT8's extra few db will extend it longer than usual!

Thursday, 12 July 2018

My New 80 / 40m Antenna

80 / 40m wire vertical groundplanes, now removed



For the past several years I have employed wire vertical groundplane antennas for both 80 and 40m, mounted a few feet from the ocean.




In the fall I layout the ground radials on the grass and in the spring, roll all of them up again. The main reason for going to the vertical was to eliminate problems with my 80 / 40m half-slopers when using my 1929 single tube power oscillators during the windy conditions usually encountered during the mid-winter '29 BK QSO Party.

The flexing between the tower's telescoping mast sections and the Yagi antennas that form part of the sloper's 'top hat' , cause the half-sloper's impedance or resonance to change ever so slightly. The directly-coupled oscillators respond to these minute antenna changes by constantly shifting frequency by several hundred Hertz, as their output load changes. These high winds can make the low-power oscillator difficult to copy under weak signal conditions as it suddenly jumps frequency. The verticals were immune to this 'wind effect' and performed very well ... sort of.

I've noticed, over the years, that the verticals seemed to produce a much better signal out on the eastern edges of the continent than they do in the central states and in the closer western (PNW) states. I decided to see if an inverted-V might produce a higher takeoff angle and give me a better signal in mid-continent and an 'OK' one on the east coast. The half-slopers on the other hand, always seem to produce a good signal both near and far, but could usually not be used with the one-tube power oscillators when it was windy ... which, during winter here on the coast, is a lot of the time!

Following the removal of the old wire verticals and several days of antenna building, the new 80 / 40m dual inverted-Vs were hoisted to the top of my 85' Balsam. After pruning for resonance, I have been able to run some comparisons between the 40m V and my present 40m half-sloper. The 80m half-sloper had already been decommissioned as it required the changing of a jumper to use and I was never able to resonate it properly for some reason. Oddly there was no problem with either the 40m or 160m half slopers, fed at the same point, as both resonated easily.

The new 80 / 40m dual inverted-V dipoles

The dual dipoles, both resonated to the CW portion of each band, are separated every 10' by 24" varnished and painted hardwood spreaders.



The old 40m sloper has always been a really great performing antenna (except for the power oscillator / mast flexing problem) and it was the one used for my 300mW Tuna Tin Worked All States, back in the fall of 2000. I've had good success with both the 40m version and the 160m version, with 159 countries now confirmed on topband using the diminutive 130' wire.


The 'Half-Sloper' was given a close analysis by antenna guru Jack Belrose, VE2CV, and described in QST of May, 1980. In his article, "The Half Sloper - Successful Deployment is an Enigma", he found that the radiation pattern was almost identical to that of a top-loaded monopole, fed against ground. The radiation field was largely vertically polarized and omni-directional while a lesser component, about 10db down, was horizontally polarized and coming from the sloping wire. The horizontal component had a figure-eight radiation pattern, slightly favoring the direction of the wire. He suggests that this antenna should be avoided due to the difficulty in getting it properly tuned.

My own experience with half-slopers have been mostly very positive, in spite of the tuning problems with the 80m version. To me, it seems like an ideal low band antenna for the small backyard, if you can get it to tune correctly. Assuming you already have a tower with some beams to add top-loading, hanging half slopers for the low bands takes up very little space. With omni-directional low angle radiation along with some higher angle horizontal radiation, all in a small footprint, what could be better for a simple wire antenna? Well, hopefully, my new high inverted-V!

For the past couple of weeks, as described earlier, I have been comparing the new 40m inverted-V against my 40m half-sloper, 'A-B' style, in real time, using the KiwiSDR network of online receivers. It seems that about 75% of the time, my old half-sloper, is just a few db better than the new V ... after all of the work involved, these results were both surprising and somewhat disappointing!

Perhaps I shouldn't be surprised after all, since the inverted-V configuration for a dipole is certainly less than ideal and the included angle in my antenna's normal position is only about 90 degrees. As well, the feedline attenuation losses for the new antenna are about 1db higher than those of the sloper. During the winter, I will be able to move one leg over to the far side of my neighbour's property which will open the apex up to a full 180 degrees. Recent testing at this angle has made the antennas neck and neck with one beating the other about 50% of the time, but the inverted-V is always better to the closer states.

Unfortunately, I have nothing to compare the new 80m antenna against but from listening to the signal on various SDR's around the continent and into the Caribbean, I have every confidence in it providing a much better signal than I have previously been able to muster on that band ... it should really help during the '29 BK QSO Party and the next NRR CW Party.

So what has been accomplished with the new installation? I have gained what appears to be a very good performer on 80m, as well as a 40m antenna that seems to be as good as the known good performing half-sloper, and should not cause any frequency-hopping with the one-tube power oscillators. My signal into the nearby PNW and central states has been improved. As well, now I can also avoid the annual radial deployment and retrieval needed for the wire verticals.

I'm still testing both antennas but conditions have been less than co-operative over the past few weeks. Hopefully when propagation picks up again, some of the European and far out Pacific SDRs can be used to further compare the two antennas ... there may yet be more to come!