Antenna recommendation for 40 and 80M bands
 

Hi All

Trying to get back to HF after a few years of QRT. I just got an HF rig, and ATU.

I am thinking of putting a wire antenna for 40 and 80M bands, but what would be the best? I am not too fussy about DX, but would like antenna that is efficient and free from RF Feedback into the shack.

Ones I am thinking of are,

G5RV
Fan Dipole cut for the bands
Inverted V Dipole
Random / Long wire with ATU and ground.

I have plenty of wires for the element, and would like DIY rather than buying ready made antennas.

Thanks

Re: Antenna recommendation for 40 and 80M bands
 

I'm using a 20/40m inverted V fan dipole. Wire from Sotabeams and RG58 "milspec" feed from Moonraker. Feed radiation and RF into the shack is sorted with a small stack of 4x material 43 toroids that the feed is looped through four times and cable tied at the antenna end of the feed. I managed to cut it with just the aid of my TX and built in SWR meter so that it's a 1.3:1 match across the band worst case. Took a while to get that right! The thing is quite low down and wedged between my house and some trees and I only run max 10W and have had plenty of contacts on it.

SSB is hell at the moment though due to the solar cycle. No luck there. Digital modes and CW for me.

WSPR spot at ~2W out on my QRP Labs QCX on 40m got me a spot in Tasmania!

Re: Antenna recommendation for 40 and 80M bands
 

Carolina Windom!

Re: Antenna recommendation for 40 and 80M bands
 

Choice of aerial: the first determining factor is usually 'How much space is available?', where 'space' means space well-clear of earthed objects and sources of interference - such as power lines radiating PLT. :devil: Plus, in most cases, with the aerial being mounted as high as possible.

Al.

Re: Antenna recommendation for 40 and 80M bands
 

Symmetrical dipole (whatever length fits!)

open wire feeders (about 4 inch spaced) to Z-match balanced ATU

Forget unbalanced ATUs with baluns after them, a balun to handle the range of impedances and frequencies is problematical.

The fully balanced nature rejects local QRM
The isolation of the ATU handles issues of PME safety.

David GM4ZNX

Re: Antenna recommendation for 40 and 80M bands
 

Yes, the bands seems really poor these days. When will they get better again?

My garden is not too big about 20M x 20M square shape, and it has a few large trees. Several cables are passing above the lawn coming from a telegraph pole at the corner feeding a few houses nearby, and they must be the BT internet broadband lines. So it will be tricky to dodgy the cables when hanging and stretching radio antenna in the garden.

My ATU is CAPCO SPC300, so it is not Zmatch? I think Zmatch tuner is EZtune one either by Isle of Man or Wight. I saw them a lot but never had one of those.

How would inverted L compare to others?

What happens when you attach feeder in the middle of radiating element instead of feeding from the end? How does the band coverage change, or would be the same?

Re: Antenna recommendation for 40 and 80M bands
 

Hi
Easiest and probably the best antenna you can have for 40 and 80 metres will be a fan dipole, easy and cheap to make, use any wire that you can find copper coated preferred.
Just adjust the length of the 40 metre first for best swr at mid band and then do the same for the 80.
No need of balun or tuner, will definitely do what you want.

If you would like more help contact me at address shown on qrz.com
cheers mm0hdw

Re: Antenna recommendation for 40 and 80M bands
 

Thank you James. Yeah, it seems simplest and cheapest option. I was a bit weary about using balun, because it could be tricky tune for some part of the band, even if it could be resonant on some. Also I have seen where antenna has good SWR, but it wouldn't radiate efficiently, so it was not making any contacts.

And Fan dipoles could be configured as inverted V under some situations, I suppose.

I was reading up about the Doublet, and was a bit wondered if the twin line feeder coming into ATU might radiate and cause RF feedback problems? But then I recall some people using Doublets were putting strong signals on 40M without sign of RF feedback or distorted audio.

Re: Antenna recommendation for 40 and 80M bands
 

Conditions are very poor at times due to Sun spot cycle.

Re: Antenna recommendation for 40 and 80M bands
 

We're around the bottom of the sunspot cycle so things should begin to improve, BUT the last cycle was rather anomalous, so you can't be too sure about predictions.

Inverted L is an unbalanced antenna, so it misses out on the QRM reducing properties of balanced ones. They can work, but they do require a reasonable earth, and are best in a quiet location.

Capco SPC300 is an American design, found in the ARRL handbook. Series-Parallel-Capacitance 'SPC' version of the classic American 'Transmatch design. It is a good ATU, but it is unbalanced. It's great for long-wire inverted-L and such asymmetric antennae. The designers thought that if you want to drive balanced antennae, just stick a balun on the antenna end of it. Simples! no very much not simples. It leaves a difficult job for the balun to do. SPC transmatch is a good circuit, but SPC transmatch into a balun is asking for balun problems, and there are better overall balanced ATU designs.

The Z-match was an amateur design, and over the years many firms have sold ready made versions and kits. SEM you've mentioned. A really nice version was made by KW and called the Supermatch 107 and supermatch 109 (a higher power variant) these were later branded Decca. They are lovely and well sought-after. I use a supermatch 109 and keep the auto ATU turned off in the Icom IC7700.

People ask 'How much power can xxxx ATU handle?' well they aren't limited by power. At some voltage the variable capacitors will flash over, at some current the coils etc will unsolder themselves. What power these happen at depends a lot on the ATU settings. Gauge ATUs on the spacing of the variable capacitors and the heftiness of inductors and the generosity of cabinet dimensions around the coils. Good construction gives low loss, and low loss is as beneficial on QRP as it is on QRO.

Confession time. I built an SPC transmatch with large capacitors and a nice roller-coaster coil. It's the size of an HP spectrum analyser (It's in an actual HP spectrum analyser cabinet!) I included directional power metering with log scales from 100mW to 1kW along with computed VSWR/return loss, and even a phase meter.

Then, I found out it effectively forced unbalanced antennae on me, and those antennae picked up every switch mode power supply in the village.

So I went balanced and I picked up the Decca/KW 109 atu from a silent key stall at a rally. In view of where the money was going, I didn't mind the price.

So my SPC transmatch is a wonder to behold. It would run away with any construction contest, but as a unit built by a professional RF designer it would be grossly unfair to enter. It sits unused in the attic and just comes out occasionally as a display item.

I'm fairly well known in technical circles, and one of the ARRL handbook authors, and that big ATU is my biggest goof in amateur radio. I leapt in and threw a lot of effort and a fair bit of lucre into building exactly the wrong thing! The better the job I made of it, the more stupid I looked!

Band conditions and sunspots limit things, but the new kid on that block is all the RF crap from every gizmo in christendom. Antenna choice is now steered somewhat by reception difficulties. If you can't hear 'em, you can't work 'em.

George Burt GM3OXX had a simple doublet between chimneys on the 4-storey flats he lived in - about the lendth of your garden. He ran 1 Watt, CW only and was far over 300 DXCC countries. Nice chap, absolute legend and sadly missed.

David

Re: Antenna recommendation for 40 and 80M bands
 

For me the important thing is the physical layout of the site: dipoles are OK if your shack is in the middle of your plot, if your shack is at one end then a dipole implies a long length of feeder. My shack is at one end of the site so I've got a 100-ish-foot end-fed longwire here, along with an old 1960s Redifon ATU.

As an earth I've got my "extended fence-spike network" as described here:

https://www.vintage-radio.net/forum/....php?p=1092363

The longwire is about 20 feet above ground, and works surprisingly well both for throughout-Europe working (ot also covers 60Metres - and I regularly work Iceland with 30 Watts from my PRC320 on that band) and also during the dark-hours of the winter months I can work into Canada/Eastern-US on 80Metres with 100 Watts.

Height is less important than you may have been led to believe - indeed, an antenna that's only 0.1-wavelength above ground is precisely what you need for "NVIS" communication over a few hundred miles.

I like my "Cloudwarmer"!

Re: Antenna recommendation for 40 and 80M bands
 

Great posts David and Tanuki. Enjoyed reading them thank you. :)

I have seen the KW107 atu many times in the rallies and eBay as well, but passed them rather foolishly. It was because maybe I associated them with the KW2000 valved tranceiver. All the KW2000s I have seen, none of them worked. They all needed work done to them.

I also read about GM3OXX. Very interesting radio and engineering story.

When I was very active on HF many years ago - it was early 1990s, I used to run Inverted L at one time, and it did make many good contacts on all bands. But then it was the Sun spot maximum time, when dummyload with 5W could work some strong European stations. Every morning 20m was full of VKs and JAs. At night North Americans would come on with vengeanes warming up the bands all night with their multi kilowatt amps and multi element beams until the dawn.

I got my DXCC within a few months with indoor dipole and quarter size inverted L. The good old days.

Now? I heard nothing but hash on 20m all day, and when I heard ON4s and F5s, I felt they were some exotic DX.

I thought it is time to cut a proper LF band antenna.

Re: Antenna recommendation for 40 and 80M bands
 

I'm surprised that there as been little mention of noise of the type produced by numerous wall-warts and other electronic sources. Putting up a dipole for 60m about a year ago, I just found I was getting an S8 level of noise as soon as the feeder connected to the transceiver.

However, I do have the particular problem of both overhead telephone and an overhead power line coming in to the front of the property and being all together too close to one leg of the dipole for comfort. If my problem comes from them, that is very hard to avoid. The whole village has overhead power lines, and the sub-station is only about 80m away from me. The noise is not being generated by anything inside my house.

B

Re: Antenna recommendation for 40 and 80M bands
 

You will have no rf returned if you correctly cut your dipole.
SWR only occurs when the antenna is unbalanced or you tune out of band,
The antenna plays no part in audio quality, that depends on the settings in the rig.
if you use ladder line or window line you would need a matchbox matching unit ( tuner) to alter the impedance back to 50 ohms, ladder line etc has various impedance depending on the spacing, 200 and anything up to 2000 ohms.
ladder line terminated into a matcher does not radiate.the old 60's matchbox and heathkit tuners are the best for ladder line.the newer tuners are not at all as good.
However if you carefully make and prune a trap dipole you will have no problems at all.it can be nearly any shape but straight seems best.

Re: Antenna recommendation for 40 and 80M bands
 

Yes, the RF feedback on my HF rig seems 100% caused by either the rig or microphone, because the distortion is noticed even when it is TXing to a dummyload.

I am waiting for other microphones to arrive for testing the audio problem.

But the CAPCO SPC 300 ATU does not have ladder line input. It is an earlier version with just one coax input. There is another input just next to the coax input, which looks like just a socket for a wire.

I also recall when running a G5RV for 40m, I cut the end of the twin line connector, and joined two lines into one, making it like a long wire, and connected that to WIRE input of the AT-230 Kenwood ATU. It worked OK on 80m at the time. The AT-230 was also a good tuner, but sold it off years ago. Not sure if the CAPCO can do that.

What about ground plane vertical antenna? Are they any good for 40 and 80M?
What are the goods and bads for the GP?

But yes, the dipole seems most easy option to try out, because I have the wire and also coax. It will cost me nothing to cut it and try out.

Any one fancy a SSB chat on 80M / 40M? when I cut the dipole for giving us reports? Please let us know here.

If it is not working for me well for environmental reasons such as too many overhead cables and trees and shrubs causing high SWR ... I don't know, but I think it would work OK. If not, then I could always try something else and compare.


Maybe we should make a 80M net for UK vintage radio forum. UVRF net or something like that on 80M or 40M? :D

Re: Antenna recommendation for 40 and 80M bands
 

60M band, I have not tried yet. For that, I need to buy a new rig, either modern SDR like ICOM IC7300, or maybe get older rig with GC, and wide band it to get the 60M.

But I heard it could be a noisy band. But yes, the noise on LF is very bad here too. I mean, every electric appliance in the house is potential cause for the noise, but also I am sure it comes from nearby outside places too.

I have confirmed noise causing source into HF in the house is, the worst is the Samsung LED TV, and then tumble dryer, washing machine, all the small switching power supplies and LED security lights and Radio Scanner and Computers and Monitors.

The only way I could tackle the noise was using RF attenuator button in TS-130SE. It works well, and really quieten down the hash noise. And I found balun could also choke the noise down.

Re: Antenna recommendation for 40 and 80M bands
 

Aerials tend to be in one of two types: balanced and unbalanced. Balanced required balanced feeder (75 Ω twin is available for a dipole); unbalanced requires an earth connection. The size of your garden (or other available space) and the location of your equipment (i.e. your 'shack') will tend to limit your choice. If your shack is approx. central to where you can erect your aerial, use a balanced aerial; otherwise use an unbalance type, but fit an earth connection which does need to be fairly short.
For your stated need, seems that a balanced fan dipole is your best choice.

Al.

Re: Antenna recommendation for 40 and 80M bands
 

My house is at the edge of the garden not in the centre, so it will make feeder very long, which may be not ideal.

For earth connection, what about earth post at the back of the HF rig and also at the back of ATU, do they all need to get connected to outside earth connection?

What are the uses / functions for the earth posts at the back of the HF radio and ATU actually?

Re: Antenna recommendation for 40 and 80M bands
 

There is only one aerial for those bands I'm afraid...open wire fed doublet. And not the G5RV version.

The open-wire is essentially losses and will take much abuse - ideally run it through space or, as in my case, past the house, hooked over a conservatory gutter, through a plum tree and finally down the garden to the feeder through some branches. My feeder is about fifty feet long.

Im being picky of course, you certainly hear more types of aerial on the bands but over the years two aerials have really seen more entries in my logbook in the "what's he using" column...the dipole and the doublet. One and the same really, sort of.

My own open-wire fed 55m top doublet has been challenged by many newcomers over the years yet still beats everything else I can throw at it. I made my own feeder and balun and the aerial runs about 20 feet up in the trees, roughly east-west.

Re: Antenna recommendation for 40 and 80M bands
 

Yes, Doublet seems really interesting antenna. I am still amazed how the wire feeder coming into the shack to be connected to ATU, doesn't radiate.

It must be special ATU, as said, the Zmatch? or Transmatch atu?

I would love to try it out, but will need the ATU. My CAPCO SPC300 has only coaxial feed. Just one input - this must be the very earliest model. Built like a tank, and weighs tons.

Re: Antenna recommendation for 40 and 80M bands
 

loop antenna plus 4:1 balun for the lower bands

https://www.m0mcx.co.uk/sg-230-feedi...oop-deltaloop/

https://www.yccc.org/Articles/Antenn...rt_version.ppt

I managed to get 128ft of wire up in a small back garden by going from the back fence, up to the rear corner of the house, along the gutters, and back down to the other corner of the garden, works relatively well.

10m extending fishing pole with a 1/4 wave vertical wire for the higher bands

Re: Antenna recommendation for 40 and 80M bands
 

You need to be careful about bringing an external earth into the house. There is an RSGB booklet about this, which basically says don't do it but if you must do it get it checked by a qualified electrician.

For an antenna which needs an earth connection you may need rather more than a spike in the ground. You either need radials, or a different antenna type which does not require an earth connection (e.g. some form of dipole/doublet).

A twin balanced feeder does not radiate (provided there is no common-mode current) because it is balanced and has close spacing. You can ensure no common-mode current by using a choke 'balun', although in many cases you can get away without one.

Re: Antenna recommendation for 40 and 80M bands
 

If all of your mains-powered equipment to which to intend to connect an 'RF earth' is connected to the supply mains via an isolation transformer, then that equipment has no connection to the supply earth. Therefore you can connect your 'RF earth' to that equipment.
Is there a flaw in that idea, somewhere?

Al.

Re: Antenna recommendation for 40 and 80M bands
 

Extraneous.

Lawrence.

Re: Antenna recommendation for 40 and 80M bands
 

I am not an expert in electrical supply grounding, but the isolation of the isolation transformer would be one issue. Not just 240V, but under fault conditions including a nearby lightning strike raising local ground potential.

Also, you don't want two different 'grounds' within the same room so everything in that room would have to be run from the isolating transformer.

Re: Antenna recommendation for 40 and 80M bands
 

What would be the effect of connecting the HF rig and ATU's earth posts to outside earth system, say old cooper pipes for mains water system? I have an outside tap on the wall in the back garden, and checked the conductivity of that tap, with the water pipes running under the kitchen sink, and they are all connected.

What difference does it make, when they are not connected at all? I suppose there would be two different situations where one is for balanced antenna system when earth connection is not needed, and the other case where the antenna is unbalanced and needing earth system.

Is it Must or Optional? Is it good or bad or no difference for the radio system?

Re: Antenna recommendation for 40 and 80M bands
 

Last night, cut the wire, and put up an antenna. I had to just go by with the garden limitation. I thought the garden was 20m x 20m, but it wa actually about 16-17m at max. And due to trees and hedges, it could only accommodate maximum 15m stretch of wire, and hung on the tree and bent L shaped for another 5m. And that is the centre element to 50 ohms coax.

And 5m of wire was connected to the coax outer braid, and then to the outside water tap, which is connected to the copper pipe of the mains water under the kitchen sink.

And it tunes 15, 20, 40 and 80m band with almost 1.1:1 SWR.

I worked a station in ST. Albans on 80M band CW at late night. I got 569, and he was 569-599 QSB. I was using about 40W pep.

The receiving on all bands has got really quiet (I mean much much less band noise but received signals were same or better), and I heard a 9K and VEs and K9s on 20M in early evening.

I will keep on experimenting with the LF band antenna getting more parts such as baluns, open wire feeders and wire for radials in the future. But will see how this antenna will perform for a while, and if it is no good, then will move on to maybe the Doublet or Loop or GP. Balanced dipole seems a challenge for this QTH due to the house building being at the side of the garden, and making feeder very long.

Here is rough sketch of my LF band antenna I put up last night. I don't know what it should be called. But I decided to make use of the outside tap as part of the earthing, and it seems working OK for tuning at least.

And the PSU doesn't make buzzing noise when tuning the 80M band either. Before it was quite bad with the buzz from the PSU. So some improvements are showing with the HF antenna now being outside.

Re: Antenna recommendation for 40 and 80M bands
 

That setup will be injecting RF currents into your house ground wiring, assuming that the water pipes are cross-bonded to the electrical earth. It may be fine, or it may cause problems of RFI with broadband routers, TVs etc. What you are effectively doing is using the mains supply as the ground, which you could do just by connecting a wire from your rig ground terminal to the mains ground in the shack. The fact that you are running fairly low power will help.

If the water pipes are not cross-bonded to the mains earth then you are using water pipes as the earth, which may or may not be a good RF earth. Be aware that ease of tuning is a sign of a low efficiency antenna, as well as a sign of a good tuner. You will also have two earths in your shack, which may have quite different potentials under electrical fault conditions.

Re: Antenna recommendation for 40 and 80M bands
 

Good point.

I will do check on the possibility that mains earth is connected to the water pipe. I have a cut mains plug with 3x open wires at the other end.

I will plug it into the mains socket, and read connectivity from the earth wire from the plug, and the water pipe. If they are connected, then yes, the mains system is using the water pipe as earth too.

If not, then likely it is separated, and clear?

Without the ATU, SWR on all bands are between 1.5:1 to 3:1

Re: Antenna recommendation for 40 and 80M bands
 

Coax feed is quite normal these days. Feed coax to a balun, then open wire to the doublet thereafter.

Re: Antenna recommendation for 40 and 80M bands
 

I feel that you are getting too much conflicting info
I worked for 35 years as a TX engineer and was also involved in antenna research which really exposed the crap published by sellers.
The best factual web site that I have seen is http://www.dj0ip.de/vertical-antenna...band-vertical/
have a look, simple but factual
Our antenna research found that apart from UHF and SHF there was nothing new in practical antenna design since the late 1930's
MM0HDW

Re: Antenna recommendation for 40 and 80M bands
 

Great site. Thank you for the link.

Just found out with DMM that the water pipes are not connected to electrical mains system.

Re: Antenna recommendation for 40 and 80M bands
 

That vertical, non-resonant dipole looks very interesting, but I think it's a new idea to me. Has anyone tried anything along those lines?

B

Re: Antenna recommendation for 40 and 80M bands
 

Therein lies the problem. There are as many recommendations as there are people. All of them will work, to different extents. All are affected by your location.

But which is best?

The measurement of any antenna, with enough precision to make comparisons valid, is a major undertaking and is famously expensive. Such undertakings are inevitably done only for military, broadcast, etc. applications where the money is available. This means users with however much clear land it takes.

The evaluation of HF antennae in cluttered domestic environments has been left to the amateur community, which seems appropriate, because we are the people who actually use such things.

Unfortunately we can't afford open area test sites and tons of equipment. We form our opinions of antennae from using them. S meters have various sensitivities, differing by much more than the gains of most antennae. Band conditions vary be even more. Some people are more careful than others, using relible beacons rather than whatever distant stations they come across. Beacons are fixed power and fixed antenna pattern so received strength variations are left to propagation and your antenna.

No-one else has quite the same location as you, so you really are on your own, I'm afraid.

There are pages and pages of articles on antennae in the likes of QST, all based on finite element analysis by programmes like MININEC. They can be interesting, but don't model your surroundings.

So that leaves generalisations:

If you live in a housing area, there is going to be terrible levels of RF noise across the lower HF/MF bands through all waking hours. Loops and balanced antennae in general, are less susceptible to this noise, and if the noise is a few dB lower from an antenna, then you can read signals a few dB lower. Insensitive antennae are OK on receive if they make the noise go down more than they reduce the signals. Verticals and asymmetric antennae are moresensitive to enviromnental noise.

Verticals can give better low-angle radiation than too-low dipoles. A popular DXers delight is the Four-Square array of verticals with a phasing box to steer it.

There is no best antenna. It's all just compromises.

There are a few things which are dependable.

Open wire feeders are much lower loss than coax cable. Coax is more convenient, though.

If you use an antenna which is not naturally resonant on your chosen frequency, you can fix this with an ATU. But this meens your feeder is running mis-matched and that multiplies the effect of feeder losses. So low loss feeder comes into its own - If you have a clear route into the ATU in the shack. Or you could build a remotely operated ATU and mount it at the antenna feedpoint. Then, coax is a great choice.

It's quite easy to lose more than half your transmitter power in an ATU and feeder. Running a balun on the antenna side of an unbalanced ATU can be even worse.

Coax cable works best in a controlled-impedance environment. Use it between a radio and an ATU or between a radio and a matched antenna. Avoid it between an ATU and an unmatched antenna.

Open-wire feeder is the least-bad choice for unmatched operation. It doesn't need screening from things away from it, but it you don't want things too close to it. Routing it can be a pain.

Expect to try a number of different antennae. Set things up so you can change things around. Use temporary lash ups. Only invest real effort or money when you've found what works for you.

Of course, we'd all like you to duplicate whatever we have 'cos it gives a nice boost to the ego :-)

I had access to a nice, large, anechoic screened room along with calibrated measurement antennae and spectrum analysers. It was fun to make a few scale model antennae and try them out. But I didn't learn as much about the antennae as I did about modelling their environments!

Have a play, have fun.

David

Re: Antenna recommendation for 40 and 80M bands
 

We have trees in the garden, but also power cables above the lawn, so it is very tricky to raise the antenna higher than about 7-8 metres, which doesn't help.

I don't want to bring the wire antenna near the mains power cable or touch it.

And the antenna I just put up is not too efficient. I have switched over to another ATU from the CAPCO, and it is having difficulty matching the antenna this time. Lowest SWR I get on 3.750 Khz is 3:1, and 3.510 is better at 1.5:1

So the Capco was tuning up anything thrown at it. It is a really great tuner, but that doesn't mean the antenna is radiating the power. The reflected power from antenna could have been either being soaked back into the Capco, or heating up the P.A of the rig?


Having said that, I worked HB9 near Zurich on 3.557 Khz on CW. I got 339, and he was struggling copying me.

I am waiting for 1:1 balun coming from China, and it is taking ages to arrive.
But if this antenna is not doing well (looks like it), then will maybe try adding 1:1 balun on it. If even at that, no good then, will move to Doublet with open wire feeder, or ground plane vertical, or even Loop.

What is the acceptable SWR for TXing with ATU?
3:1 on 3.750 khz sounds too high.

Re: Antenna recommendation for 40 and 80M bands
 

I used to have a long dipole, 200', made from blue telephone wire, centre fed with twin feeder into a balun, it would tune up on any band, any that were not spot on could be made so by adjusting the length of the feeder. Unfortunately after many years it fell down back in the winter, probably been up for 20 years though. I am going to replace it but with a shorter one as I have a redundant tower that supported a wind turbine for one end.

I also have a 40m dipole made from figure 8 telephone wire, I split it to make an approximately 40m dipole and used the twin part as the feeder. I used this when on holiday in Scotland with my IC706 via a KW Easy Match balanced only ATU and it worked brilliantly, worked well on 20 and 80m with more or less zero SWR.

My original 40 and 80m antennas were home made and could easily be tuned by making them a bit long and then cutting a bit off at a time until min SWR was in the middle of the band.

Peter

Re: Antenna recommendation for 40 and 80M bands
 

Yes these work well and good where space is restricted BUT note you MUST use a good tuner, the newer ones with internal balun will not work, use one of the old Matchbox types with well spaced tuning vanes and good coils.
This design and nearly all the others on the site are very old designs and can not be faulted, were in use many decades ago so have stood the test of time.
We installed a medium wave TX in the Middle East in the 1970's, 1480 was the frequency and output One Megawatt, the vertical antenna was of this design,
MM0HDW

Re: Antenna recommendation for 40 and 80M bands
 

Hi Pete
that is the way to go, make your own,
Next time you make a dipole and need to shorten just fold back the excess wire , wrap around the antenna wire and tape or cable tie.
If you cut sods law may require you to make it a few inches longer.
cheers
MM0HDW

Re: Antenna recommendation for 40 and 80M bands
 

Whatever you do, don't go for the "End-fed Zepp" design - despite being published in loads of antenna-handbooks for 50+ years it "Doesn't work" either in theory or practice.

Mr. Moxon G6XN reported such in his "HF Antennas for all locations" book in the 1960s, despite which the design still shows-up regularly.

There *ARE* ways to make an end-fed half-wave antenna work well; they just don't involve ladder-line feeder with one end 'terminated' into the infinity of free-space!

Re: Antenna recommendation for 40 and 80M bands
 

What antenna have you created?, any antenna can be made resonant and the way it has been designed will get it resonant in mid of the frequency band you choose, Why are you messing with a 1-1 balun. it will do nothing.
you are doing something wrong,
Just create an antenna from one of the designs in the site I sent you,
People try for a 1-1 match, if that is achieved with coax feed something is wrong, a dipole has a impedance of 73 ohms, the coax feeder is 50 ohms, so 1.5 to 1 is the best one can get,
In practice anything up to 2-1 is acceptable.
If you create a correct antenna your tuner will not have much to do so don't try to design an antenna yourself, it has all been done successfully such a long time ago
cheers
MM0HDW

Re: Antenna recommendation for 40 and 80M bands
 

That is good well done, you have made a Off Centre fed dipole, your 5 metre wire to the water tap is part of the antenna which will tune easily with a old type tuner, no balun, Just see the site I sent you and you will see your antenna, not sure why you are so concerned about earths, your rig has an earth connection and that is your protection, if you mess with an rf earth do not have it connected to the mains earth, radials cut for bands in use enhance these OFC antennas and all vertical designs a lot
an RF earth is not the same as an electrical earth,
Hope to work you on the bands
cheers
MM0HDW

Re: Antenna recommendation for 40 and 80M bands
 

Presumably, the part sentence "your rig has an earth connection and that is your protection" refers to a connection to the a.c. mains earth.
So if the rf earth is not to be connected to the mains earth, how do you suggest that is to be achieved, since that 'rf earth' will be joined to the metalwork of the rig . . . which will be at 'mains earth'?

I did make a suggestion in my post 23 to solve that conundrum, but, judging by its responses, it seems that it was not a good idea.

Perhaps I've misunderstood you, or that I've missed something obvious (not unusual :-])

Al.

Re: Antenna recommendation for 40 and 80M bands
 

If your house is powered via what used to be called a PME connection, then bringing any unbonded earth into it is verboten. Rather a lot of 1960s houses onwards have one conductor a combined neutral and earth. A fault in the supply wiring, interrupting this conductor to one or more houses can cause all the earthed stuff to go live (via whatever loads are on in all the homes affected, combined) The voltage can approach the full 240, and the available current will be the total load current of all the homes affected. There are no fuses in neutral and earth connections!

The 'fix' for this unlikely, but nasty risk is for the wiring regulations to require ALL touchable metalwork in such houses to be bonded together. All water and heating pipes, gas pipes, metal sinks etc. No separate external earths may be brought in. They would create a shock hazard, so local earths are required to be bonded to the provided 'earth'. Someone standing outside must not be able to reach in and touch anything bonded to PME.

There is an RSGB booklet on how to handle these systems. If you are doing anything with earths entering your house, you need to find out what system you have in order to know what regulations affect you.

It's easy to say 'who will know' but in the low probability event of trouble, you can find yourself in a fatal accident enquiry, or with your house insurance ruled void just when you need it. Much as you may want, you can't nip back in a tme machine and change it. The probability of it happening is low, but the consequences can make up for that in nastiness.

Note that the wiring regs have no concern over RF noise and interference. Trying to fix that and staying legal is quite a puzzle. But, other people have had to deal with it already, hence the RSGB booklet.

The vast majority of people are unaware of this issue and don't even know there are different systems let alone know which one they have. Ignorance of laws is not an acceptable defence should anything go wrong.

On a course, I was told that there had been cases of fatal shocks received by people outside touching brass taps for hosepipes.... with a copper pipe to the bonded water system. PME earths aren't allowed to be exported outside. I suspect my house may be the only one on the estate with a deliberate plastic pipe to the outside tap.

Earthing is a minefield, and some of the rules are seriously counter-intuitive.

There often is no labelling telling you what sort of system you have, yet you are required to do different things.

You thought aerials were difficult?

David

Re: Antenna recommendation for 40 and 80M bands
 

The antenna is changing the lowest tuned SWR time to time as well. Sometimes, it goes up, and sometimes it is down. Checked all the connections and seems fine, it looks like more ATU issue?

But 1:1 balun was ordered about 2 - 3 weeks ago. At the time, I thought that would make things simpler for antenna. Just attach some wires at the end, and coax feeder, and it will work. But now I learned that it is not that simple.
But 1:1 balun - would it not reduce the band and EMS noise and also prevent common RF current on the coax feeder at least? Also was hoping it would reduce SWR on the feeder.

I read on the internet - not to get voltage baluns, but get current baluns, and don't get 4:1, but get 1:1. There are a few videos explaining why on youtube, but haven't watched till the end. Was too long video.

Yesterday, HF band condition was poorest I have seen. There was nothing on all bands, and even 7 Mhz was dead all day. The only band active was 80M with many nets. I worked one special event station near London in the early evening on 3.750 Mhz. He struggled copying my calls, but persisted trying, and we made contact. It was good.

I tried again late at night, as someone was calling CQ on 3.740 Mhz, but he couldn't hear me saying my audio was too rough.

I think my HF rig has TX distorted audio issues - not sure if it is mic or the rig itself.

Re: Antenna recommendation for 40 and 80M bands
 

Yes, the antenna is matching very well on all bands from 7Mhz and up wards. On 3.5 - 3.790 Mhz, it is 1.5:1 - 3:1 SWR with ATU.

Sure. I will try to be on 80M today between 3.700 - 3.710 Mhz from about 2:00 pm, and 4pm. And in the evening from 8:00pm. And tomorrow, Sunday as well. If you are around, please give us a shout please.

If anyone is around that time on 80m, please give us a shout for giving us audio report and chat :) tnx.

Call sign is GM0MOP.

73 Jay

Re: Antenna recommendation for 40 and 80M bands
 

Matching is easy. An effective ATU can even give a good match into a wrong-value dummy load resistor.

Don't concentrate too much on matching. An antenna has to also be a transducer between electrical signals and electromagnetic waves. Otherwise a dummy load would look like a good antenna.

The signal strengths you get from various places matter, but then so does the background noise. on transmit the proportion of the power radiated in a wanted direction compared to that wasted heating things up is the figure of merit.

Matching needs to be close enough for the transmitter to give its rated wellie.

Audio distortion could be RF getting into the microphone connection, if your shack is runninng RF-hot.

David GM4ZNX

running a station for the scouts today. I'll listen around if I'm on at that time.

Re: Antenna recommendation for 40 and 80M bands
 

I feel the audio distortion is very likely to be due to the POWER Mic supplied with the old TS-130SE.

I don't have any other Kenwood/Trio mic, so I am stuck with this mysterious power mic for the time being. The supplier promised to send me Trio mic, but it is not arriving for over 10 days since the promise.

But yes, I used to think low SWR is absolute must for TX antenna, but that is not the case, I learned. That is good to know.

Yeah, please gives us a shout if you are around.
I think we might have worked before on 2M band many years ago. GM4ZNX sounds familiar call to me.

Hope to hear you on the band. 73

Re: Antenna recommendation for 40 and 80M bands
 

And if the house uses the TT system - which this one does - how does that change things?

Al.

Re: Antenna recommendation for 40 and 80M bands
 

Not sure what Earth system this house uses for the mains power, but it is definitely not connected to the water pipes. Checked a few mains wall sockets earth with the water pipes under the sink with DMM. No connections.

Re: Antenna recommendation for 40 and 80M bands
 

Your plumbing may use plastic pipes in certain places. How old is your house?

Al.