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Using 20 meters for more local coverage?


#1

Does anyone have any ideas or techniques for using 20 meters (portable) for more local coverage? By local I mean 150 miles or less. That first skip on 20m seems to be going out 300 miles or so with what I’ve been doing.

I’ve had success with low dipoles / NVIS on 40 meters. The Buddistick will do about the same thing on 40 at least some of the time.

Am I asking 20m to do something that is not possible?

Thanks for your thoughts and ideas.

73 de Eric / KB3UYT


#2

In reply to KB3UYT:

Sometimes 20 will support very short skip, even as short as fifty miles, but normally it just can’t support the sort of distances that you need. Forty or sixty metres will usually perform better, or even eighty outside of the summer high D-layer absorption.

73

Brian G8ADD


#3

In reply to KB3UYT:

My QTH is on the coast of North Yorkshire, approximately half way down the UK. The North of Scotland and Land’s End are both 300 miles distant. In 7 years of chasing SOTA’s (14,000 contacts) I have only heard UK activators on 14 MHz about six times and most of these were by ground wave from my local SOTA, some 20 miles distant.

73
Roy G4SSH


#4

In reply to G4SSH:

In 7 years of chasing SOTA’s (14,000 contacts) I have only
heard UK activators on 14 MHz about six times and most of these were
by ground wave from my local SOTA, some 20 miles distant.

A bit more common than you imagine, Roy! I have just started doing 14 MHz activations this year and I have already worked you on that band on 5 occasions in 2012:

11 April
12 April
17 April
29 August
30 August

I have also worked Kevin, G0NUP, several times on 14 MHz.
:slight_smile:

73,
Walt (G3NYY)


#5

In reply to G3NYY:

A few more than I thought Walt, but not a reliable band for short distance.
Hopefully the peak of the sunspot cycle (if/when) should help the higher bands.

73
Roy


#6

In reply to KB3UYT:

Like Roy, 20m wouldn’t be my choice for such short range. I’d be looking at specifically setting up and using NVIS antennas. The bands to consider are 80/60/40m. I’ve found 60m in the UK to be particularly good for giving me coverage over 25-400miles. That’s using an inverted V dipole with the apex low, about 4.7m AGL. I don’t use 80m so I can’t comment much on the band but 60m is badly affected by D-layer absorbtion during the Summer. From October to April it is very effective for QRP SSB working. At the bottom of the sunspot cycle it gave excellent inter-G coverage when the skip was far too long on 40m.

I would suggest that you probably want to consider full size antennas at these lower frequencies rather short antennas with loading coils.

The other band I’d be looking at is 2m. Either FM or SSB. I’d expect to have few problems working 0-500miles with 10W of 2m SSB and a 13-17ele beam to similarly equipped stations. So a 150mile range with a few watts of 2m SSB and a small beam is not unreasonable especially if you’re well located as you will be on a summit. 2m SSB is no longer as popular and find stations with beams and rotators will be less common. You still find plenty of fixed stations with a vertical antenna, probably a 2/70cms antenna possibly with some gain. A vertical beam will again allow considerable distances to be worked on FM or SSB. Of course, a small PA will do wonders on 2m if you can carry the batteries and PA itself.

Andy
MM0FMF


#7

In reply to MM0FMF:

I think that the truth is that there just isn’t an ideal band. One day one band will be better, another day it will be another band that does the job. It seems to me that going out equipped for several bands is the sensible plan, but that means carrying an antenna that will work on several bands, or several antennas, and of course you will get a number of different opinions on the best antenna to use.

Just for reference, I go out equipped for 80/60/40/20 metres with a W3EDP antenna, and 2 metres FM/SSB with a dipole.

73

Brian G8ADD


#8

How about 15m?

It sounds daft, but I have had a couple of local(ish) contacts on 15m - I have worked M0TUB (42 miles) and GO0VOF (22miles), both with excellent 599 signals. I can’t think it would be ground wave at that distance.

I used a low 40m dipole in both instances.

Experimentation is the key!

73
Colin
M0CGH


#9

In reply to M0CGH:

It’s surprising how far ground wave can go. When I set up on a summit I have a quick check on propagation. I’ve got RAF VOLMET 5/11MHz and Shannon VOLMET 5/8MHz in the memories of the 817. You can always hear RAF VOLMET on 11MHz via groundwave. Sometimes you can hear it via F2 backscatter and it arrives a different time to the groundwave and you get QSB and other effects on the signal. RAF VOLMET on 11MHz is just audible at my QTH, Inskip (Blackpool) is about 150miles distant. There again there are some big antennas there and RAF VOLMET doesn’t run 5W from an 817 so perhaps it’s not surprising.

I’ve worked Phil G4OBK on 14/17MHz F2 backscatter on a few occasions. But Phil has some damn fine antennas at his QTH never mind a good set of ears on his head wired to some decent operating skills. He’s worked me when HF conditions are good by beaming at the reflection point not the direct path and I guess he’s had the boiler well stoked and a good head of steam on his PA to attract my attention. His signals at my end have been very watery and fluttery, so heaven knows what my QRP signals were like at his end.

I’ve never experienced that kind of signal strength so perhaps it was SpE. I’ve not enough HF experience to know if it was F2 as 22miles via ionospheric reflection would suggest a massively high critical frequency.

Andy
MM0FMF


#10

In reply to MM0FMF:

I actually have video footage of the signal from Mark, GO0VOF, he was just a little weaker than VE1WT who was calling at the same time. I don’t really understand all the ins and outs of HF propagation myself. I did also work Phil, G4OBK on both 20m and 2m CW - I think Phil is contactable regardless of frequency :wink:

73
Colin
M0CGH