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Quick Jaunt to Walbury Hill


#1

I work at Thames Valley Park, Reading and in the evening was due to go to a colleague’s leaving do. What to do between leaving work and the do ? - answer, a quick jaunt to Walbury Hill about 30 miles west.

I left work mid afternoon so arrived on site about 1430z with sunny weather but clouds building. Access is easy here so I quickly got to work assembling the antenna. Mid way through this there was a heavy shower but fortunately this didnt last too long so I was able to safely get the FT857D out. I have been working 60/40/30M a lot recently so for this activation I thought I would try the higher bands. I took along my End-Fed Half-Wave (EFHW) vertical, which covers 20m to 12m. It almost works on 10m but there is too much stray C in my matching box limiting its upper freq to 27MHz.

The EFHW vertical is an excellent SOTA antenna as it is easy to set up and doesn’t need radials. I use a 10M pole and tape a wire to it, which has links for 20/17/15/12M. I built my matching box to easily handle 100W so it is perhaps bigger than it needs to be for the 5W I was using.

I started out on 14059 and there was a nice run of chasers. I then switched to 14260, which was great until some 20M contest started and a guy with no ears started calling 1KHz lower. I can’t believe he couldn’t hear me even with 5W. So then I tried 18086 and was very pleased to work VE1WT and KK1W who was very loud. Unfortunately I then ran out of time and had to pack up.

Overall a nice activation. I must come back here as the views are spectacular. Maybe try 2M next time. Thanks to all the chasers who worked me.

73s,
Andrew G4AFI


#2

In reply to G4AFI:

I started out on 14059 and there was a nice run of chasers. I then
switched to 14260, which was great until some 20M contest started and
a guy with no ears started calling 1KHz lower. I can’t believe he
couldn’t hear me even with 5W.

Sign of the times Andrew. In fact, G4FSU wrote a one and a half page article on this very subject in Novembers RadCom.

As someone who has spent a lot of time working the higher HF frequencies on SOTA activations, I can often be forced to move at least half a dozen times during the day. It’s all too common for operators to jump onto a frequency and with not so much as a “by your leave sir”, just start calling CQ. They no longer bother to listen or ask if the frequency is clear …the hijacking of my forty metre frequency last Saturday on Belling Hill, being a classic example.

73 Mike
2E0YYY


#3

In reply to 2E0YYY:

no longer bother to listen or ask if the frequency is clear

Often (as happened just now whilst I was listening to Hans DL/PA3FYG/P) the first indication you get is an S9+60 tuning tone that has you trying to block your ears and turn the volume down all at once. One can only hope that one day they’ll try tuning on full power when there’s such a bad mismatch in their system that the reflected power will fry their PA before the safety cut-outs have a chance… :confused:

73, Rick M0LEP


#4

In reply to G4AFI:

I found the same effects with my EFHW and matchbox. Using a 1/2wave for 20m, i.e. a 10m length of wire, I can tune up on 17m and 15m easily but matching on 12m is a bit ticklish. With a 1/2wave for 10m, i.e. 5m of wire, then tuning on 10m, 12m and 15m is easy and 17m is tricky. I was using about 1m of counterpoise in both cases. There should be next to no current in the counterpoise when the correct length of wire is used if I understand the theory correctly.

In the first case too much capacitance with tuning cap fully unmeshed and not enough C fully meshed in the second case. It’s not hard to carry two lengths of wire. I used a T68-6 toroid and a wee polyvaricon in mine so it’s really for QRP use only.

I should model the radiation patterns for each wire at the different frequencies just in case there is something horrible to avoid and also to see if the counterpoise direction as it lays on the ground has any significant effect. But I’ve been able to work across the pond using the 5m length with the feedpoint on the ground on both 15m (CW) and 10m (SSB) using only 5W from the 817 so some RF is getting out.

Andy
MM0FMF


#5

In reply to MM0FMF:
Hi Andy,
I use a bigger variable, a reasonably wide spaced Jackson but I have the same situation: fully meshed it resonates about 13.5 MHZ and fully unmeshed around 27MHz. The solution for me is to put in an extra link for 10M and build a separate matchbox for 10M. There have been some good openings on 10M recently that I have missed out on :frowning:

I personally haven’t found the need for a counterpoise. I have tried with and without and cant find any difference. Probably the length of coax between the rig and matchbox is acting as a counterpoise. Like yours, mine is certainly getting out. KK1W gave me a 559 yesterday with 5W on 17M CW, which I was very happy with. I am still not use to how far one can get with QRP and a very simple antenna. A few years ago I was using 2 x 3-500Zs to a 3el monobander on 17M !

Andrew,
G4AFI


#6

In reply to 2E0YYY:
Hi Mike,
Yes it is very annoying isn’t it. All we can do is QSY and try again. I was pleasantly surprised how well behaved everyone was on CW when on 14059, it was a different story on 14260 SSB.

Andrew,
G4AFI


#7

In reply to G4AFI:
Hi Andrew,
Thanks for the interesting report on your recent activation of Walbury Hill.
I was pleased to catch you on 18mhz, the last contact before you went QRT.
Walbury Hill is my nearest summit and yours was the 100th logged SOTA activation.
I usually cycle there (about a 35 mile round trip) when I feel in need of some exercise.
I was there on Saturday , 99th activation .
Yes it can be very frustrating running QRP on the higher HF bands as so many stations are running 1Kw into beam antennas and if you are unlucky enough to be caught up in the wall of EU stations calling a DX station who is listening ‘UP’ then you stand no chance and the only opion is to move well away and self spot again . (or QSY to a different band).
Good luck with your next activation.

David G3RDQ


#8

In reply to G3RDQ:
Hi David,
A pleasure to work you on 17M. I noticed that you had been at Walbury Hill only a few days earlier; I didn’t realise I was the 100th activation, what an honour ! Walbury Hill is probably the nearest to me as well but considerably further than your 35 mile round trip from my home QTH. It is nearer from the works QTH though.

Andrew,
G4AFI