Just one thought - one simple tip I forgot to mention. Avoid earth loops in your shack. Don’t daisy chain earth wires to various pieces of equipment. Best practice is to create a common earth bonding point to your external earth or make an earthed bus bar and earth every piece of equipment to it independently, including PCs. That might help unless you already have it. Again its trial and error. It might make things worse or better - isolating your mains via filters might also affect how effective this measure is. For earth in my shack I use the screen from good quality RG-213 coax with the sheath and dielectric removed and use that to connect the various electronic items chassis to the earth.
I have an AlexLoop [which I rarely use] mainly cos 1) it doesn’t go down to 80m, and 2) you have to stand next to it to tune the frequency and rotate it for the incoming signal. Our house is at 25m ASL and the take-off at head height in my plot is poor due to surrounding buildings and tall trees.
Our village is in an AoONB (Area of Outstanding Natural Beauty) which places restrictions on type and placement of antennas. My long wire [made of UltraLite thin wire] is practically invisible and my neighbours didn’t notice it until I pointed it out.
If I put a magloop up high enough to be effective my wife - not alone the neighbours or the council - would complain that our house looks like a giant TV detector van [a cultural reference that probably means nothing to folk outside the UK where they don’t have to pay an annual TV license and detector vans drive round the streets looking for non-payers].
Hi Andy
You need to stand up and assert your rights as a licenced radio amateur Andy - take them on including the XYL LOL… Awkward neighbours do eventually give up once permission is obtained and it can be gained in an AONB although the AONB manager will scrutinise your application and will have his say… It is possible to get councillors on planning committee’s on your side, especially if they get the impression that neighbours are ganging up on you and getting their heads together, writing letters and fabricating reasons such as TV interference, car windows coming down to due RFI, garage doors opening etc as they did with me. The planning officer ended up recommending acceptance of my Hexbeam and 6+6 4m/6m yagi last year, and it was passed unanimously by the planning committee - the Tennamast was passed on appeal to the Planning Inspectorate in 2018. Some neighbours ignore me as a result, no loss to me. I enjoy my radio too much to bother about them, most of them don’t even live in my road and cannot see the aerials.
I’ve been rethinking about the possibility of a ½-wave 80-m dipole on my plot without the need for a support pole.
I make one some years ago and was very happy with its performance - when portable and at my previous QTH – on 80m and higher bands using an ATU.
But, before I go to the time and trouble of making and erecting one, can I expect - all other things being equal - that a half-wave dipole will be less prone to receive noise than my existing end-fed long wire which has no counterpoise and probably an ineffective ground plane over my plot (consisting of a few cms of soil over 345-million-year-old Dalton limestone) ?
My wife and I have been out with a long tape measure this afternoon [important to get her buy-in up front]. There’s a mature tree on the edge of the property about 7m from the shack and I could attach a ~1m-long nylon cord to one of its branches and a lightweight 1:1 balun at the other end. There would be about 29m from the balun to the existing nylon cord (on a tall tree) at the far end of the back garden where my long wire is currently attached. There’s 20m in the opposite direction from the proposed balun to a tree on the edge of my front driveway. This tree belongs to my neighbour but I think it would be legal to attach something to one of the many branches that protrude well over my side.
One concern: the end of the dipole wire at the driveway end would be 5m away from those previously-mentioned pesky electricity & telephone cables on telegraph poles running up on my side of the road. The dipole wire would be almost at right angle to those cables (say about 80 degrees) so I think the risk of induced EMFs is low.
Another concern: the wire over the driveway would be visible from the road. It may attract attention. But I know from discussion with Phli @G4OBK and others that the low height of the wire (lower than the top of my bungalow roof and the Diamond X50 colinear on 2m pole on the chimney) does not need planning permission. I see nothing in the AoONB regs that would be a problem either.
If you are going to fit in a dipole, you might consider a doublet fed with twin line of some kind, rather than an 80m dipole - it could be more versatile.
I’m pondering a new wire antenna as mine had to be removed recently to facillitate a rebuild of the chimney that supported it. I’ve been using the spreadsheet linked in an earlier thread, and posted by Armin @DL6GCA. Armin’s translation, together with a bit of Google translate action clarified how to use it to calculate the length of the “legs” together with the length of feeder. (I also picked up a tip from Owen Duffy’s website to avoid copper covered steel conductors as used in many commercial ladderline feeders, as they can be very lossy at LF due to skin effect)
I have nothing in the air yet, and less room than you have to play with - but I do have high noise on 160m and 80m!
Anyway, just a thought. I’ll be interested to hear how you get on, and will update when I have something working…
The main information you really need before making decisions about antennas is “what and where is the source of the noise?” Without that, you cannot know whether putting an antenna closer to the power lines, the house or near the neighbours will increase the noise pickup or reduce it. Some dedicated hunting with a portable radio could help you to answer that question.
I’ve just been wandering round our plot and the road by our driveway with a KX2 with a telescopic whip listening to a quiet frequency about 3700kHz on SSB with a wide filter (~3500Hz). The high-band whip was ill matched for 80m and signals were very weak but I hoped the setup would be good enough to pick up any local source of noise.
There was an increase in noise as I got within a few metres under the overhead power and telephone cables in the street and it became a maximum when standing directly underneath them. Without a cherrypicker to raise me and the KX2 vertically 8m or so, it wasn’t possible to say if the noise was from the mains cables at around 8m up or the telephone cables at around 6m up. It was very localised to the line of the cables and the noise dropped to ‘normal’ before getting to the other side of the road.
There was a small increase in noise when holding the top of the whip within a few cm’s of our own overhead telephone cable. There was no increase doing the same with the overhead mains electricity cable running to our house.
The rest of my survey around the house, shack, gardens back and front, near the neighbour’s house, etc was uneventful.
I’m not sure if any firm conclusion can be drawn between the noise detected from the overhead roadside cables and the high noise on the low bands using the long wire antenna whose ends are located between 15m and 45m away from the cables and mostly at right angles to the cables. In other words, yes, the overhead cables are a noise source but how localised is it? Do they extend enough to affect the LW antenna? Not possible to answer without being able to change the separation distance.
Even indoor antenna can hear pretty well with modest receiver like FT817ND. Below my test on 30 m with second floor Buddipole September 2020. 160 m and 80 m are difficult due to antenna size. Indoor 80 m magnetic loop is big or needs large capacitor and has some safety concerns. I would check reception and propagation first on https://pskreporter.info/pskmap.html.
OH, I Wish!! We have to pay through the nose each quarter for a TV/Radio licence in Germany and what is worse - the government-owned national TV stations that this is supposed to pay for now have lots of commercial adverts on them! So we are “paying” twice. No need for the vans here though. You have to register where you live and for every property, there has to be a TV licence. Whether you own or rent no difference. If you don’t have a TV in the house - no difference - “you can get our stations over the Internet” - so you still have to pay the licence fee.
73 Ed.
I guess you’ve seen this video have you Andy (since you have an SDR Play - this process would seem to be a good match for you).
In my case I replaced the tv antenna amplifier swiching supply with a 230/15vac trasformer and linear lm7812.
You might have benefit with a good ground system in the shack.
Can you use a fishing pole to set up a temporary dipole/doublet? This would be an easy way to see if it helps before going to the trouble of a permanent installation. Also make sure you have good common mode choking. GM3SEK has good advice. I have the low, mid and high band chokes in series and it does help.
I’ve pretty much concluded that’s the next step. If I hadn’t cannibalized my portable 80m dipole (to make a 20/10/6 linked dipole), I would have tried it yesterday. No matter, I’ll make another and erect it on my 10m SOTAbeam pole.
Thanks, Richard. I’ve downloaded the PDF. I’ld prefer to read it rather than get back to doing the wallpapering but my wife will have expected ‘progress’ when she’s gets home. Doing QRP portable most of the time, it’s never been a problem but it’s time to bone up on chokes.
His longer article, “A Ham’s Guide to RFI, Ferrites, Baluns, and Audio Interfacing”, goes into the detail behind the chokes, plus guides on reducing RFI in the rest of the shack, not just the antenna.
I’ve changed my mind (fickle or flexible?) about making an 80m 1/2-wave dipole [because of its poorer performance on many higher bands even with a good ATU] and instead I’m gonna make an 80-10m OCFD. My home QTH antenna for donkey’s years was a [USA-made] heavy-duty QRO 80m windom and it always gave good performance on most bands [this all predated 60m].
I still need to have the balun (now a 4:1 current balun) supported by the aforementioned mature tree 7m from the shack so I’ll need to run a longer support cord at the ‘short wire’ end to reach the other tree due to the 36%-64% split in the wire lengths (compared to the 50%-50% for the dipole).
I understand, if I use a current balun comprising a twin-core [rather than the cheaper but less effective single core], I shouldn’t need any further choking (loops of coax, ferrite rings etc).
Yes, the full size 80m and down OCFD is a good compromise if you can fit it in Andy. If you get the feedpoint into the 7m tree and then run the ends out as an inverted vee and it works well at that height - great! I’ve been using a similar arrangement since Jan 2017 here and have no desire to change it, albeit I only use it on 30-40-60-80m. As mine is higher than yours I have a 6:1 balun at the feedpoint and believing the theory, I chose to choke the feeder again at around 20-22 feet below the feedpoint with a stack of ferrite rods. The theory supposedly says this will produce some vertical radiation from the feeder, (according to the article I copied the design from). The feeder starts out in my case as mini 8 down to the choke, so I get plenty of turns on that, I then go into RG-213 down to ground level and then buried Ecoflex 15 for the lions share of the cable run back to my shack. How the extra choking supposedly works with a balun at the feedpoint above it only the Lord knows, but that’s how I made mine up and I haven’t been minded to change it since it went up, as it works quite well. I resonated it perfectly for the 40m band by tweaking the lengths of the top a little, proportionately each side. 40m for me is the most important band in terms of SOTA chasing. The 80m match is acceptable without an ATU in the CW/FT8 part of the band, but if I go up to SSB above 3600 KHZ the auto ATU in the radio will take care of it. The only band the AUTO ATU will not tune the antenna to a perfect match is 60m, so when using the OCFD there I use an external tuner.
If you can obtain permission or sneak a strongish fibreglass pole into the tree (if it is climbable) then more hieght above the branches will make the aerial more effective and would probably help reduce your local noise level. I use 25 or 55mm wide X 600mm long velcro straps obtainable from ebay sellers, to secure my three antenna poles into the upper branches of a beech tree. The velcro straps are then backed up with very large tyrwaps to make the strapping more secure. You may still think that your noise level is high, but the best comparision would be to see what you can hear of the stations that others may be working and then hopefully you will also manage to work them yourself. Good luck with the project.
Phil, I watched your YouTube video with your poles ‘growing’ out of the top of your beech tree. I know that a similar arrangement here would be aesthetically displeasing to my wife. Striking a balance between my hobby interests and my wife’s (gardening) is a tricky balance. I think any small improvement in the antenna performance by raising its height from where it’s virtually invisible to where the rest of the village can see it is not worth it.
I’m hoping merely going from an end-fed LW with no counterpoise to a dipole [thereby not requiring a ground plane] will reduce the noise from local sources even if the height of the wires is about the same as before.
I won’t need to make the OCFD an inverted V due to the relative heights of the three support trees. However, my plot is on a hill [actually the whole village is - first settled by Norsemen as a defensive position over the Kent estuary] and the ground drops away towards the end of the back garden. So, whilst the wires will be roughly horizontal, the heights above the ground will increase going from the short end to the balun to the long end.
P.S. The balun tree is climbable but I’m not sure I want to try going up to the higher branches. I might try a hook taped to the end of my SOTAbeam pole to get a lanyard over a high branch.
What you propose sounds perfectly acceptable for SOTA Chasing if that is your main interest Andy. I am confident your noise level / signal to noise ratio against an end fed without a counterpoise will improve significantly as a start point, then you need to look at your shack and the local environs, but getting inside peoples homes to investigate specific issues you may find by DFing is difficult. If you do any electrical work in their homes it is a gamble as if something goes wrong with something electrical in their home you may be held responsible. Its tricky. Where I lived before I detected some terrible interference in one of the nearest homes to where we lived, in the green belt just outside of the town. I found the source by going down the road with a small medium wave radio until I found the strongest source. The interference was spoiling reception in the 160 and 80 metre bands over a radius of over 400m in every direction. The people allowed me in to their home to investigate. They allowed me to turn off their circuit breakers one by one until we found the ring main concerned. Then we started swtiching off appliances. The source turned out to be a Thomson TV digi-box / HDD recorder. The unit case was very hot to the touch even when it was on standby and not recording. The digibox had been in service for some years, yet the interference just started out of the blue and was affecting my reception. They were happy to take it out of service and give it to me for investigation. I scrapped it on their behalf and they thanked me for alerting them of the defective equipment. I was lucky as they were good people.
I need my aerials as high as I could get them, in fact I’ve just bought a “DX Challenger Extra Long Telescopic Antenna Support Mini-eXteme Nebula” from M0MCX: NEBULA
Its 41 feet long (12.5m) long to fix in the tree in place of the 7m Lifes a Breeze pole, so that will give me 61 feet in the vertical for 80m DXing in the winter months. When I got married in 1996 the XYL knew what she was getting as I had an 18m versatower in my garden where I lived in Scarborough at that time (much to the chagrin of some of my neighbours!). Some believe in live and let live and some don’t
Have you a portable battery operated radio set that has the LW/MW bands ?
If yes, i would take it outside and with the help of the directivity given by the ferrite antenna try to find the source of the problem before trying to find a cure !
Set it at the end of the MW band 1620 kHz and if the QRM is not that sharp in frequency you will be able to track it until you find the source.
