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The best laid plans - SP-010


#1

Having built the linked HF dipole (described by GW4BVE) some time ago I decided it was time to go out and tune it up, not having the space to do it at home. So, last Sunday, the weather being pleasant when I got up, I decided to go out to the local high spot (Winter Hill), get the antenna resonant and do an activation using HF, 2 metres, 4 metres and 23cm, should be a breeze I thought ! A 30 minute drive to the parking place just off the TV transmitter access road and I was ready. The only thing was, I couldn’t carry everything in one go so I decided on doing HF first.

So, after walking into the activation zone, the HF antenna and mast were put up and connected to the SWR meter and FT-817 with SLAB. Luck was with me and the 10 metre section was resonant - great ! Now on to the other bands, 20 metres was not quite resonant but the SWR was within acceptable limits. Now the fun started, 40 metres was way off with the antenna being too long. No problem, just shorten it a bit, however, where were the wire cutters ? they were in my pocket half an hour ago but not now - obviously somewhere in the heather ! A fruitless search for twenty minutes produced no sign of them, but let’s try 5MHz anyway. No chance of resonance on 5MHz and with all the messing around I managed to upset the settings in the FT817 so ended up operating “split” or sometimes getting TX-ERROR whenever I keyed the mic - why now, with no manual with me ! Eventually I had to do a “factory reset” and managed to sort most things out, but by now I had had enough and decided to leave HF for another day. By this time the heat was building up and I was dripping, and the flies were bad…

Never mind, let’s pack up HF, take the stuff back to the car and try 4,2, and 23.

Another ascent up the hill and 2 metre FM was used with the FT817 to bring in 9 chasers, not many considering the location but at least the hill was qualified. Now for 4 metres, only FM from a handheld with “rubber duck” but I should raise something - no such luck, nothing, zilch !

Getting a bit fed up now, extremely hot, flies even worse than before, and I had managed to find just about the only wet bit on the hill to kneel down in.
Ok, set up on 23 with the FT290, Microwave Modules transverter and homebrew antenna. GB3CLE was coming in ok, a bit weaker than expected but it was there. CQ CQ - nothing (as expected really) so spotlite…

Then at S9+++ there was a GW so give him a call - all I get is QRZ, there’s someone there but completely distorted and very weak…

What’s wrong now ? A complete check on the connections, cables, battery voltage etc found nothing wrong - then it dawned, the attenuator needed between the 290 and the transverter was missing (it was at home on the 4 metre transverter !) so that explains the distorted signal as the transverter was being overdriven. Horrible memories of the transverter datasheet warning about never, ever, connecting a transmitter without the attenuator now came flooding back - have I now blown something up ? I have still not had the courage to conduct any tests yet so we still live in hope!

So, after what should have been a breeze of an activation, and carrying the 4 metre rig, FT817, FT290, transverter, SLAB, 23cm beam, SOTA pole and HF dipole up and down the hill in swealtering and very humid conditions I ended up with a 2 metre FM activation that I could have done using the pocket sized handie, a possibly seriously damaged transverter, a still untuned HF antenna,
and an FT817 that needs all the settings and memories being re-input.

To cap it all it was then a trip to ASDA for the weekly shop ! But I still made it to the local for a couple of much needed pints just before closing time (it closes at 4pm for some reason).

I’m off to the Cairngorms soon with a trip up ES-001 planned but if this simple trip up Winter Hill is anything to go by then I may as well not bother taking the radio !

Keith, G8HXE.


#2

I’ve had activations like that myself Keith, although it sounds like yours was a particularly unfortunate one!

GL in the Cairngorms.

Tom M1EYP


#3

In reply to G8HXE:

What a tale of woe!

I am glad I was at least able to give you a 2m contact. I have had a 4m antenna sitting in the corner of the shack for 3 weeks now but work has prevented me doing anything with it. I am also suffering from the flu otherwise I would have thrown it up on the portable mast along with the 23cms beam to work you on those two bands. For future reference I only have FM on 23cms but if I get advance warning I can be beaming in the right direction.

On the subject of the GW4BVE linked dipole I am somewhat surprised at the problems you encountered.

My first linked dipole was my own design and was made for 60/40/20m and used bullet connectors, it took me about an hour and a half to tune/trim it, because for some reason it did not want to play on 60m at first. When I discovered power-poles I decided make a new version and make it to work on 80/60/40/20/10m. This just happened to be when John’s design appeared on his Flickr pages. I printed off John’s design and I compared it to my existing antenna. On 60/40/20m John’s design was within a couple of millimetres of mine, so because I had miles of spare wire I threw caution to the wind and cut all the sections exactly to John’s measurements. Maybe it was luck and I was using the same gauge wire but it all worked first time with no adjustments.

I do hope you sort everything out for the trip to Cairngorms and then maybe I can work you from ES-001. Enjoy your trip.

Regards Steve GW7AAV 73


#4

In reply to GW7AAV:

I think you may find variations in the length depending on the type of wire used, thickness and type of insulation will have an effect. My own antenna was a 40m/60m one. Later I added 80m. I had a figure based on the length of the 40m/60m legs for how long the 80m legs should be. As a cross check, John’s measurements were within millimetres. On air testing showed the tuning to be great.

Andy
MM0FMF


#5

When I made my linked dipole I used Maplin’s heaviest equipment wire, can’t remember what the ‘gauge’ is, but it is similar in thickness to one of the cores of normal household 3 core cable.

I used Burton ARC’s dipole calculator on their site-

http://www.burtonarc.co.uk/dipole.htm

I started with the shortest legs first, then kept adding additional lengths after each VSWR check. Mine had perfect SWR for each band section I had cut for. Maybe I was just lucky, but I think the Dipole calculator works well.

73 Colin


#6

In reply to GW7AAV:
It was probably my own fault with the linked dipole as I made each section a bit longer than the details stated. I have made numerous dipoles in the past and often found that the measurements used were a bit out in practice, so now I always make them longer than stated and then trim them down - no problem with that and it always seems to work out ok, but not this time as I lost the xxxxdy wire cutters in the heather and long grass!!

Looks like the transverter is ok though (my biggest worry). I fired it up today (with the attenuator fitted this time) and monotored it on another receiver and it sounds ok.

Now hoping for a quick return to complete the “unfinished business”, although I won’t be able to claim any points next time.

Keith.


#7

In reply to G8HXE:

I had a similar experience with a 5 megs dipole a couple of years ago, but my Swiss army penknife came to the rescue - it needed the blade sharpening afterwards, though!

73

Brian G8ADD


#8

In reply to G8HXE:

Regarding the dipole I would have done the same thing if I had not done a comparison with John’s design and my first one. The wire I used was .5mm PVC coated.

Regarding the the transverter…phew! I look forward to working you on 23cms sometime soon.

Steve