EFHW tribal knowledge sought.

[M1BUU]

I’m wondering if anyone can give me some pointers and pass on some knowledge.

In a few weeks I’m setting off on a multi-day trip by bicycle in the Inner Hebrides. There’s no SOTA opportunities but I would like to do some radio. My first issue is that I don’t have a lightweight, small SSB capable 40m radio. I’ve ordered a 40m band kit for my Radio Kits Explorer and I’m looking to swap it over to 40m as a last resort.

Antenna wise, I have a 5m Ron Thompson fishing pole obtained from Go Outdoors many years ago. The pole collapses to a length about the same same as the top tube on my bicycle. I have a decrepit 4m pole but I don’t think it will be much good for a 40m antenna.

I’ve only really used dipoles and ground planes, I’ve never really understood EFHWs. I do have a Czech ALT Altoids end fed tuner. I was thinking about implementing an EFHW for 40m.

I would like to know things like is it usual to guy the pole? I assuming the pole is guyed to hold it up and then the wire is suspended inverted vee style. My Ron Thompson pole is of unknown qualities, I’m not sure how conductive it is. Maybe I should just make a dipole?

40m is the main band of interest but I would like to try other bands if possible. I’m thinking about packing my MTR-5B. The EFHW could probably be re-purposed to cover some different bands.

I was thinking about making a feeder cable from the rig to the tuner with a choke, is this a good idea? The feeder would be made from some RG-174 that I have. I know there’s some loss issues.

Ideally I’d love to take a KX2 with AATU and a piece of wire but my budget will only stretch to the piece of wire!

Hoping that somebody can give me some practical tips.

73, Colin

My accommodation and cooking equipment is in this photo but no radio equipment.

[M6GYU]

I can’t help you on the aerial bit but wow, that looks like a very little for a trip up north. Look forward to reading your blogs.

[G4TGJ]

Hi Colin

I normally use my 6m pole (it’s probably nearer 5.5m as the end broke off) for my EFHW. I attach guys to the pole, velcro the matching transformer about 1m up from the bottom, plug the banana plug at one end of the antenna wire to the transformer, clip the wire to the top of the pole and raise the pole. I then walk with the wire winder until I reach the end and stake the end. So it’s an inverted L, not a V. This means the pole is by my operating position.

I do use a choke (a few turns of RG174 on an FT140-43 toroid) but it’s mostly not needed.

My 20m long EFHW will work on 40m, 20m and 15m without having to change any links.

73 Richard

PS. We should do that joint activation so that you can see it for real!

[DL6GCA]

Hello Colin

A lot has actually been written about EFHW.

I consider it to be one of the most practical antennas ever. You can use the thinnest wire and keep them small. You can build them with traps or coils for different bands. The classic one is already in resonance at 40/20/15/10m. The 1:49 Unun is quickly wound and can be installed directly on a PCB for QRP. I don’t even use a reel but wind like Ignacio EA2BD shows on the YT video. It couldn’t be any smaller.

I always use the thin coax cable and use 0.05 lambda of the shielding as a pigtail. Then a few turns of the coax around a toroidal core and everything is good.

The question of the mast is not a problem. Many have their Inv.V dipoles on the lattice mast. Of course, the wire should be at some distance from conductive supports. The EFHW doesn’t care whether it is set up as Inv V or Inv L or something else. Maybe the SWR isn’t that great, but it won’t destroy your power amplifier.

The advantage is: You look for a place where you want to sit… and then set up the antenna! No matter how!

If you are building an antenna, first wind the unun and then cut the wire to length. The coil of the Unun always has a bit of an influence on the length of the wire.

e.g. EFHW for 60/30/17m (contest free zone antenna) :

73 Armin

[M1BUU]

Hi Armin,

Yes, I realise a lot has been written about EFHW antennas, I guess that’s what makes it difficult to find what you’re looking for. I was looking for the practical stuff like Richard has stated above.

I’ve seen the MW0SAW solution which seems to just integrate the matching section on to a SOTAbeams style wire (kite) winder. I have the KD1JV ALT tuner clone, so I may as well use that rather than trying to make a dedicated matcher with wire cut to ‘resonance’.

I could probably make a crude guying system from cord and a zip tie for the pole. Another zip tie could hold the wire to the pole and yet more zip ties could hold the tuner to the pole. I hadn’t thought of that before Richard stated that he fastens his transformer to the pole.

Thank you for the tips, I think I have some ideas to try.

73, Colin

[EA2BD]

Hi Colin,

I’d support what others suggested. Installing close to 20m wire inverted Vee at around 5m appex is my frequent setup and I run that way 40m just perfect. The Vee shape produces no interaction with the mast, even if it’s a carbon rod.

They told you tha antenna will also work on 20 and 15m as well, along with your MTR-5B.
Taking into account you’ll use the ALT Tunher I guess you’ll have no isses to tune in those three bands. Just to make sure try to setup and test it prior your trip! I gues the tuning will be touchy, maybe.

I don’t know if the soil is grassy in Inner Hebrides. If that was the case you can simply add rope to both ends of your EFHW and use anothe short rope for the mast, exactly as I describe here in my video:

Knots for portable Ham radio (Nudos para una antena portable)

In the other hand, if the soil is rocky, you could use other way to deploy it: rocks in the ends / certain support for the center mast, etc… Being your mast short as it is, and holding the wire a little distorted not to form a straight plane plus that single cord, the antenna is well supported and stable.

The video describes another interesting knot to hold the wire in the appex. It works for me all right and is very easy to setup and hold the wire without needing clamps or ties.

Good luck in your bike-xpedition! 73 Iggy

[M0RWX]

Hi Colin,

I always preferred a link dipole for 40/20m for SOTA until …

@M1BUU

I’ve seen the MW0SAW solution

The @MW0SAW EFHW is a great antenna used by many activators. Together with 5m of RG174 coax, it makes a lightweight multi-band antenna which I setup as an inverted V.

I use a Decathlon Caperlan 6m telescopic pole which is identical to the SOTAbeams Carbon-6.
On most summits, I either use a post to strap my pole against, a (SOTABeams) mini pole stake kit or slide my pole into a piece of pipe wedged in between some rocks.
When it’s really windy I tend to take my heavier pole (Tactical Mini) which I will guy.

Good luck with your bike trip.
73, Robert

[M1BUU]

Thank you Ignacio! This is the kind of information that I was seeking.

I sail on the 29th May, I’m hoping to be on air during the afternoon. Maybe around 1600utc. I want to get my radio and antenna system tested before then. I’m hopeful that the 40m band parts for my RK Explorer will arrive this week. Re-working for 40m should be fairly easy as the IF remains the same, it’s just the band pass filter and low pass filter that needs changing. (Of course I’ll probably have to do a realignment as the firmware will need resetting.)

73, Colin

[N8TGQ]

I gave up cars a long time ago, so got good at carrying radio gear on my bikes. Use your bike as a base or tripod to hold your antenna mast up. I used an old mobile antenna mirror mount. Replace one of the clamping bolts with a threaded rod with wing nuts. You can position the mount to give you the straightest attachment point, whether the bike is laying down or leaning against something. Then lash the mast alongside the rod.
I used the ALT tuner with a 40 meter MFJ QRP rig for years. The feed line between the 2 was 6" long. No counterpoise and wire was around 20m. Try it, you may be surprised!

Have fun!
Rick. N8TGQ

[N8TGQ]

Forgot to mention- I would be taking the MTR. 40 hasn’t been that good during the day for me. That same 20m wire for 40 will also work for 20 and 15m. Then if you wind the far end of the wire in to the resonant points ( about 8.5m for 17 and 15m for 30), you can cover everything with one wire, no traps and no links. Simple is good!

[M1BUU]

Thank you Rick.

I won’t have my bike with me at the operating position, but I understand how that might work otherwise. I’m a CW op with little experience of phone, so I’d pefer to use just an MTR, however I believe the chasers of WAB squares etc mainly use SSB.

Thanks for the useful information about antenna length.

73, Colin

[DL3TU]

Hi Colin,

@M1BUU

I would like to know things like is it usual to guy the pole? I assuming the pole is guyed to hold it up and then the wire is suspended inverted vee style. My Ron Thompson pole is of unknown qualities, I’m not sure how conductive it is. Maybe I should just make a dipole?

Yes, I usually guy my pole at a height of approx one metre. I use a little triangular shaped piece of plywood and three short pieces of rope. It works with a thin antenna wire if the wind is not extremely strong.
The EFHW is inverted vee. This way, conductivity of the pole doesn’t matter and you can use different poles on different occasions (carbon fibre or glass fibre). It looks like this:

@M1BUU

I’ve only really used dipoles and ground planes, I’ve never really understood EFHWs. I do have a Czech ALT Altoids end fed tuner. I was thinking about implementing an EFHW for 40m.

A wire length of approx 20 metres will do. If you add a link at approx. 14.5m it’ll give you 40, 30 and 20m.
I guess you can use that tuner or make a very simple UnUn like this one:

TinyCoupler for EFHW dipole

If you want a bit more efficiency, you can stack two toroids (FT50-43) or use a larger one. It’ll not be perfect but it works.
A more versatile tuner for EFHWs can be found here: WordPress.com. It’s more effort but will tune almost any length of wire. You’ll need an SWR-meter, though!

@M1BUU

I was thinking about making a feeder cable from the rig to the tuner with a choke, is this a good idea?

I don’t use a common mode choke and had no issues so far with the MTR-3B. It could be worth carrying a toroid or two with you, so you can make a choke if required.

Good luck and enjoy your trip!
73, Roman

[G8CPZ]

Hi Colin,

If you’re cycling a long way [and I’ve done 4- or 5-day tours with heavy pannier bags, the last one in my late 60’s] you will want to minimize weight and size but still have a decent antenna performance. When your bottom is saddle-sore and your legs feel like lead (as mine did for 7 hours cycling a day) you might curse carrying too much stuff.

It seems you are doing only 40m which keeps it simple, and a monoband HF EFHW is easy to make and tune (especially if you have or can borrow an antenna analyzer). I have several (professionally-made) tri-band EFHWs, one using a trap and the other a removable link, and it’s a bit tricky/time-consuming to cut or extend the wire lengths (at both ends) to get the VSWR ‘dips’ in the CW [or SSB] areas for all three bands. For a single band, it’s easy and I’ve made a heavy duty (Kevlar wire) 40m EFHW for use with a kite including a QRO 49:1 UnUn. For a cycling tour, I would use SOTAbeams UltraLite wire or similar and a homemade QRP UnUn.

For donkey’s years I used 5m or 10m of RG174 to feed the EFHW as a sloper at the top of the pole. Nowadays, I sit near the pole and feed the EFHW at the bottom of the pole with 2m or 3m coax. It seems just as good to me.

Since last autumn I switched the config (from sloper) to inverted-L (or really an inverted-7, as I usually have to slope the ‘horizontal’ section to ground). I also tried inverted-V for a while. People will insist they are better radiators [technically, they are] but honestly, I can’t tell any difference based on my reports received or given on average over many activations. So, if I were in your (cycling) shoes, I would probably erect a bottom-fed sloper for convenience and damn the perfectionists who insist you need a ground plane. I only ever use a GP (counterpoise wires) with my vertical.

I always guy my 6m pole and think it’s necessary in very windy conditions (like where you’re going). However, some north of the border, Fraser @MM0EFI I think, instead manages to pile rocks on the base of the pole. I wouldn’t want to risk cracking the lowest pole section (nor carry some extra ‘boot’ to protect it) and often there’s a paucity of spare rocks at many summits. I never use the antenna wire as one of the guys, which is why I think all my wire antennas have been so reliable after so many years.

If you trim/tune the EFHW for the SSB section of the 40m band, and are QRV near the resonant frequency, you won’t need an ATU. But, if you want to do CW as well [without an ATU] it would be best to use an AA to check how the VSWR varies across the band with your chosen config (sloper, inverted-L, etc). I’ve found even changing the config from an inverted-L to an inverted-7 (i.e. the angle of the ‘horizontal’ section w.r.t. the vertical section) moves the resonant frequency quite a bit.

Do some distance training on your bike (with weights in your pannier bags) before you go. I didn’t do enough and paid the (painful) price. Good luck and have fun.

[G8TMV]

@M1BUU

I do have a Czech ALT Altoids end fed tuner

That isn’t really an EFHW tuner, (I’ve got one) it’s a long wire tuner - there is a difference. However with a 52ft wire and a 16ft counterpoise it works pretty well. I’ve rigged it as an inverted V and as an inverted L and it doesn’t seem to make much difference.
Rough Inductor settings for mine (all with the Capacitor link open):
40m: 4+1+0.5
30m: 4+0.5
20m: 0.5
17m: 2+0.5
15m: 1

Mine will not tune on 60m with that wire, but you could carry an extension.

Colin (a different one)

[G4AZS]

@G8CPZ

I wouldn’t want to risk cracking the lowest pole section (nor carry some extra ‘boot’ to protect it

I carry a length of bicycle inner tube about 30cm long. This slips over the lower part of a walking pole to protect it when wedged in rocks, or a wire fence. I then bungy the antenna pole to that.
In my pack, the bit of inner tube is used to store the aluminium guying pegs.

[M5OTA]

I use a trapped EFHW for 20/30/40M with a @k6ark matching unit. Deployed as an inverted V with a 4m pole. No co-ax, just the antenna straight onto the BNC matching unit and plugged into the radio. Which is sometimes an MTR 3b. I use one of the little sotabeams antenna insulators at the end by the rig and peg it to the ground - that’s right, one end of my antenna is on the ground! I have another insulator in the middle for the pole mount, then a bit of string at the other end of the antenna and a peg. As per @EA2BD I use another bit of string to the top of the mast to create a tripod affair. Usually pitch it with the string into the howling gale so it is taking the strain, then the antenna is just stopping it falling one way or the other.

Maybe not the best antenna config RF performance wise, but works well enough for me on activations (and occasional holiday chase) and is simple, small and light. (antenna + pole + pegs = 216g)

Have a similar arrangement, but with an EFRW that I use with the KX2 with ATU.

Tony
M5OTA

[M1BUU]

Fortunately I won’t be cycling all that far. I think my first day invlolves around 7.5 miles from the ferry to the campsite.

I don’t particularly want to concentrate on 40m but I figure that’s where the WAB square chasers will be.

I hope to have some fun for myself on the higher bands with CW.

Thanks for the tips.

The parts to re-engineer my Radio Kits Explorer arrived today. I’ve got three weeks to get my kit sorted and tested.

73, Colin

[MI0PYN]

I’ve seen a number of references to the @MW0SAW EFHW, but my Google-fu seems to be letting me down.

Is this available as a kit, or built, or are the details on building this yourself published somewhere “officially”?

I have not found any definitive info other than a few YT vids of it in use, and a whole bunch of recommendations. I’m sorry if it has been put somewhere obvious…

73,
Stefan MI0PYN

[MW0SAW]

Can I ask what wire you are using for your antenna please, that looks super thin and hence compact? If you have link even better!
VY 73
Steve
MW0SAW

[MW0SAW]

Hi Stefan,
Please see my details on QRZ.com.
73
Steve
MW0SAW