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The moment


#1

And my god what a moment

Flux is well up, the sun spots numbers are up

And even carlsberg could not reproduce the moment you get your report from VK2/ST-008
on 20m. what make syou think this is my first Australian sota contact

Andrew what was you running at time

Here a TS120V, 10w, full wave 40m loop homebrew, Standard mike

Karl a very very happy QRP station


#2

Well done Karl. Ah I see you have corrected the reference to vk2/st-008 :wink:
Good luck.
Mike


#3

Christ, yes so i did see what you mean now :blush:

Thanks for pointing that out mike just double checked with gents in question got calls mixed up. Just confirmed with andrew we have worked each other and best bit is 10w either direction used oh hell yeahhh.

Karl


#4

Congrats Karl - you see it IS possible on SSB to contact VK wire antenna to wire antenna and only 10w. Next step is to do it from a SOTA summit as an S2S - which I’m sure you will do soon.

Ed.


#5

Hi Karl,

Well done on your first Aussie summit to summit contact, I am sure Andrew VK1DA was equally surprised to hear to you. :slight_smile:

73, Andrew VK1NAM


#6

Hmmm I wish :smile:

It was made from me Home station, neg S2S, that,s next :slight_smile: yet still on 10w and the home brew full wave loop 40m

Karl


#7

Andrew,

Having recently commented on a topic of Karl’s I was fairly sure I knew his callsign when it turned up in my log as I wrote from the phonetics. I think I said to Adan, I think I know this guy. It’s Karl, he has been dying to work a VK activator.

Karl,

I’m fairly sure I would have had a better signal with my vertical antenna. I only took the linked dipole on this trip, I had no plans to work any DX, it just happened that way. The conditions must have been just right.

here’s to the next contact, may it be soon…

Andrew vk1da


#8

Andrew

Big pleasure to catch you on air. Made my morning
Did hear you chasing down that German sota on 14290, 20m minutes prior to contact on 14303. On 14290 you were stronger and louder.

Yep conditions have swung about for sure.

Biggest kick for me was learning you also on wire antenna and only 10w .

Still buzzing 24hrs laters 73s

thanks again

Karl


#9

Hi Andrew (1DA) - is that what you find? That the vertical is better for DX? I have been reading up on this as I’d like an antenna for the home QTH, for non-DX stations. Basically an activator has to be two countries away from me before I hear them (on 20m, 40m is a little better). Web pages I found suggest that polarisaton for DX contacts is irrelevant as the ionesphere mucks up polarisation in any case. So vertical to horizontal or vice-versa should make no difference. I did also read however that the angle of raditaion from a vertical allows closer in contacts. That seems to be the opposite of what you are saying. I am currently using a 40m full wavelength horizontal wire loop antenna, similar to what Karl is using - in fact we are both trying different options such as feed to the loop to see what works best.

Ed DD5LP/VK2JI.


#10

Hi Ed,

A properly configured vertical will always produce a better signal for distances requiring a low angle of radiation, when compared with a relatively low inverted Vee dipole (7m max at apex). DX performance improves markedly with antennas that have more radiation at lower angles. This is basic text book fact.

Polarisation is irrelevant if the signal has been reflected by the ionoshere. It is different for line of sight comms, such as occur on VHF and up, because the ionosphere is not involved.

A properly configured dipole at an appropriate height (well over a half wave length) may well out-perform the simple quarter wave vertical with elevated radials. The dipole may also be somewhat directive but the nulls off the ends are greatly reduced in the inverted Vee format and at lower heights such as 7m squid pole height. typical low dipoles are almost perfect omnidirectional antennas.

A slight disadvantage of the vertical as a home antenna is its tendency to receive more local noise. There are plenty of amateurs using a vertical on transmit and a quieter horizontal antenna for receive. your TS2000 has a receive antenna port, so you could do the same without needing external relays etc.

73
Andrew vk1da


#11

Thank Andrew,
Without wanting to Hi-Jack this thread further (although I know Karl is interested in the answers the same as I am) what would you suggest as an antenna to get the closer in stations on 20m (Austria, Czech republic etc), or is it simply a fact that with skip distance I will never get to hear these? I have tried a 3 element tribander minibeam and that did not work well at all (possibly becuase I could not get it high enough). Would an OCF dipole at a low height be a better NVIS antenna? The horizontal loop antenna here is at about 9 m agl.
I know about the separate receive antenna port on the 2K and could indeed use that if it turns out better to have a separate rx and tx antenna.

73 Ed.


#12

Yes. They will need to use lower bands such as 40/60/80. Of course that brings a whole new can of worms to play with.


#13

Carry on gents this is getting interesting

Karl


#14

Karl, I have sent you a couple of article references via PM. One states that NVIS only happens at 10MHz and below while the other says it’s effectiveness “drops off” above 8MHz up until 30MHz when it is not practical. That latter statement would sugest that NVIS can take place at 14MHz.

I’m definitely seeing the problem on 20m where stations less that 600-700Kms away are not audible to me while they are getting 5-9 reports from stations that I can hear who are about 1000Km away from me and 5-9.

As with everything in antennas, it’s worth experimenting. One article suggests installing a switchable counterpoise under the antenna. Switch it in for NVIS “local” stations and out for DX.

I think my first test will be to lower all of the masts 1 or 2 sections and see if I see any difference to “local” stations on 20m.

Ed.


#15

Critical frequency Ed. Google it! :wink:


#16

Reply to myself, oh dear!

Ed, here is a current real time foF2 (critical frequency) plot from ips.gov.au. You can view their site to see how this data is generated. The thing to note is the colour of the display above West Africa. This suggests a 12MHz signal from a 12MHz Yagi pointed straight up at the sky would be reflected back down. The ionisation is driven by the Sun and you can see the patch that is most reflective is the bit that’s had most sun. As the sun moves West then the patch moves West. It lags the Sun by a few hours.

So there’s nowhere today where 14MHz is suitable for true NVIS.


#17

OK so Critical Frequency is not the same as maximum usable frequency MUF, nor related to it?

So the question remains, when the Critical Frequency is (for the sake or argument) 8MHz, how can one communicate with another station on 14MHz that is say, 450 Kms distant - is it simply not possible?

Ed.


#18

It’s directly related to it.

MUF = CF / sec( angle )

CF is the critical, and angle is the incident angle to the reflecting layer. Work out the angle from the slant range and the layer height.

14MHz skip distance is around 700kms. If you work someone over a shorter distance and they’re strong it’s probably Sporadic E. It they’re weak and fluttery it’s probably back scatter

This is good info: http://www.tpub.com/neets/book10/40f.htm because it doesn’t show single path reflections.


#19

Hi Ed,

Andy has answered your question perfectly, with not only words but pictures.

Experience shows that short skip on 20m only occurs when ionisation is very high or when there is sporadic (hence unpredictable and unreliable) E layer ionisation.

The best way of working them is to use a lower frequency as per Andy’s suggestion.

It is another example of how the bands do not operate in the same way, each has their strengths and weaknesses.

oh, there is another way to increase your odds of working weak signals… you know what that is…

73
Andrew
vk1da/4 today but without any radio gear


#20

Hi Andrew,
The only problem with that idea is that of late many activators around Europe have only activated on 20m not on for example 40.

As for the other suggestion, if the path is not possible on SSB, it’s also not possible on CW. I guess marginal paths would be better on one of the digital modes (CW, PSK etc.) but if theres no E’s or backscatter, and the MUF/Critical frequency is too low, then there’s no possibility of a contact in any case.

Next question - how are other stations in Europe at the same distance away from the closer (200-300Km) activators as I am, working them, when I can’t hear them - Groundwave and a big beam?

Ed.