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For portable Amateur radio activities batteries are needed. Some equipment needs a lot of power and some doesn't. My homebrew external Iambic memory keyer runs on approx 8 volts and only uses about 4mA (0.004 Amps) when it's running so a small battery is ideal.
Some of my friends were talking about using the cells from discarded disposable Vapes for powering their equipment, so I decided to do the same. A local vape shop was happy to give me several used vapes from their recycling bucket and after some thought and experimentation I've come up with two of the 3.7 volt cells in an old vape housing with the mouthpiece end replaced by another rear end. One end has the output connector to power the keyer and the other has the balance lead for the charger so that both cells get equally charged.
Some of my friends were talking about using the cells from discarded disposable Vapes for powering their equipment, so I decided to do the same. A local vape shop was happy to give me several used vapes from their recycling bucket and after some thought and experimentation I've come up with two of the 3.7 volt cells in an old vape housing with the mouthpiece end replaced by another rear end. One end has the output connector to power the keyer and the other has the balance lead for the charger so that both cells get equally charged.
EFHW antenna - Part 3
Apr. 25th, 2024 10:30 amThe photos show the completed main element of the antenna stored on its winder and a close-up of the completed loading coil.
The wires are blue and white, the orange cord is attached to the tail of the antenna and is used to secure it to either the ground with a tent peg or a convenient tree or fence post. The yellow plug connects the antenna element to the feed-point coupler, the black circular object is the fitting for the top of the mast, the white block is the end insulator and the black Velcro strap secures the feed-point end to the base of the mast.
The wires are blue and white, the orange cord is attached to the tail of the antenna and is used to secure it to either the ground with a tent peg or a convenient tree or fence post. The yellow plug connects the antenna element to the feed-point coupler, the black circular object is the fitting for the top of the mast, the white block is the end insulator and the black Velcro strap secures the feed-point end to the base of the mast.
EFHW Antenna - part 2
Apr. 24th, 2024 09:29 am
The multi-band EFHW antenna has two sections of wire separated by a coil which can be linked out when not needed. The coil acts as a trap on the 17m band and as a loading coil on the 60m and 30m bands. With it linked out (shorted) the two sections of wire form a single element used on the 40m, 20m, 15m & 10m bands. The photo shows the coil before the windings were covered with black heat-shrink protective tubing.New EFHW antenna coupler
Apr. 23rd, 2024 01:55 pmOver the last few months I've been building a new antenna for portable use. I wanted something which was lighter in weight and less bulky than the standard multi-band link dipole I've used for several years on my SOTA (Summits on the Air) activations.
The new antenna is an End Fed Half Wave (EFHW) and is usable on 7 of the Amateur radio bands. The first part to make was the coupler which connects the antenna to the radio.
This device, as well as providing a physical connection also transforms the impedance of the antenna from approx 3000 ohms down to the 50 ohms which the radio needs to operate efficiently. The antenna has a slightly different impedance on each band and to accommodate this the transformation ratio of the coupler is switchable between two values.
The Red connection is to the actual antenna wire, the silver connector is the feed to the radio and the black connector is for the 'Counterpoise' which is (in non-technical terms) a type of earth which is required to make the antenna work efficiently.
The new antenna is an End Fed Half Wave (EFHW) and is usable on 7 of the Amateur radio bands. The first part to make was the coupler which connects the antenna to the radio.
This device, as well as providing a physical connection also transforms the impedance of the antenna from approx 3000 ohms down to the 50 ohms which the radio needs to operate efficiently. The antenna has a slightly different impedance on each band and to accommodate this the transformation ratio of the coupler is switchable between two values.
The Red connection is to the actual antenna wire, the silver connector is the feed to the radio and the black connector is for the 'Counterpoise' which is (in non-technical terms) a type of earth which is required to make the antenna work efficiently.
Ham radio contact QSLs
Feb. 20th, 2018 12:41 pmHam Radio operators often confirm their contacts by "QSLing".
In the old days these were postcards containing the contact information and a cartoon or photograph to fill up the space. These days we often use the Internet in various ways to do the same thing, but, many Hams still exchange actual postcards.
To keep the postage costs down many national radio societies run a "QSL bureau" as a central clearing house, so members can effectively share international postage costs.
I had an envelope of about 20 cards arrive this morning, cards from all around Europe and the world, best DX (long Distance) among them being cards for 3 contacts with Japan.
My favourite card from this batch was one from UA3NFI in Kostroma (about 200 miles NE of Moscow) in Russia.
In the old days these were postcards containing the contact information and a cartoon or photograph to fill up the space. These days we often use the Internet in various ways to do the same thing, but, many Hams still exchange actual postcards.
To keep the postage costs down many national radio societies run a "QSL bureau" as a central clearing house, so members can effectively share international postage costs.
I had an envelope of about 20 cards arrive this morning, cards from all around Europe and the world, best DX (long Distance) among them being cards for 3 contacts with Japan.
My favourite card from this batch was one from UA3NFI in Kostroma (about 200 miles NE of Moscow) in Russia.
Big Sister at work
Oct. 1st, 2017 10:46 am
Being a big sister comes with big responsibilities it seems. Martha watches over Imogen.Grandfather again!
Sep. 29th, 2017 11:43 am
I'm pleased to announce that my eldest daughter and her husband have presented me with a second granddaughter, Imogen Rebecca. She was born on Wednesday morning and mother and baby are both home and doing well.
While making breakfast I was distracted by a dripping noise from the ceiling. Investigation revealed a damp bulging patch which I easily put my finger through directly under where the shower drain is in the bathroom above.
I've made the hole bigger, since the damaged part will need to come down anyway when it's repaired and sure enough there is a shower trap visible with a lot of lime-scale over the entire body. So it looks like the seal between the shower tray and the drain/trap has failed.
ETA: After removing it I discovered that the body was cracked. A replacement has been obtained.
A rather fuzzy photo looking straight up:
I've made the hole bigger, since the damaged part will need to come down anyway when it's repaired and sure enough there is a shower trap visible with a lot of lime-scale over the entire body. So it looks like the seal between the shower tray and the drain/trap has failed.
ETA: After removing it I discovered that the body was cracked. A replacement has been obtained.
A rather fuzzy photo looking straight up:
Bee Orchids
May. 25th, 2017 07:54 pm
Recently a neighbour pointed out a small plant growing in the middle of my front lawn and said did I know what it was? Closer investigation by the two of us had me none the wiser but he said he thought it might be a Bee Orchid (Ophrys apifera). Apparently they wild seed easily and they like the local chalky soil.I very carefully avoided it when cutting the grass, it would be a mistake to call it a 'lawn', and looked at it occasionally noting that it was getting bigger and then that it appeared to have flower buds.
I was away last weekend and when I got back the flower buds had started to open. Today I took some pictures, the best of which is on the right. It's called a Bee Orchid because the flowers look as if a Bee is feeding on the nectar, this attracts actual bees to pollinate the plant!
Visiting Family
May. 23rd, 2017 07:31 pmAt the weekend I visited my daughter and her family. The main reason being to see my Granddaughter M who is nearly two. She has grown quite a bit in the months since I last saw her and is now talking quite well too! She really likes books, if you sit down then she will bring you one to read.
She is definitely not a "Pink Princess" sort of girl, she much prefers playing with her Duplo and tractor or out in the garden on her small climbing frame and slide!
Here she is in her one Dad-power tractor at a local Garden Centre, she hasn't quite got the hang of the steering yet!
and here in another of her favourites.
She is definitely not a "Pink Princess" sort of girl, she much prefers playing with her Duplo and tractor or out in the garden on her small climbing frame and slide!
Here she is in her one Dad-power tractor at a local Garden Centre, she hasn't quite got the hang of the steering yet!
and here in another of her favourites.A couple of days of SOTA activations
May. 23rd, 2017 06:27 pmI spent some of Thursday and Friday of last week doing four Summit on the Air (SOTA) activations. They were only one point summits and it was more an exercise in completeness than anything else. They were all close to Cardiff and Newport in south Wales and the longest walk from the car was only about a mile each way. I used a mixture of techniques for the activations including FM on VHF and SSB and CW on HF.
There was an impressive array of antennas on one of the summits, making my own setup seem quite small by comparison.
There was an impressive array of antennas on one of the summits, making my own setup seem quite small by comparison.Time Travel Photos
May. 10th, 2017 07:28 pmCan you spot me? This was taken in 1959 when several of my cousins were visiting for the day!
After spending some time on the radio yesterday evening I went outside to lower my antenna mast. After releasing all the clamps I watched it slowly descend...Except that it didn't lower completely. I coaxed it a bit to try and get it all the way down, but in the dark I couldn't do much so I left it.
This morning it's still in the same position. I'll investigate a bit later (because it's a public holiday and I don't want to run the rather noisy air compressor this early).
Hedging my Bets
Apr. 7th, 2017 05:48 pmSince it seems to be popular at the moment I've created a Dreamwidth account and set it for cross posting to LJ as well.
If I've got things right then this message should appear on both sites.
If you are on DW with a different user name from LJ then please comment so that I can add you.
If I've got things right then this message should appear on both sites.
If you are on DW with a different user name from LJ then please comment so that I can add you.
More construction, 60m EFHW Mk. II
Apr. 3rd, 2017 11:12 amAbout three and a half years ago I constructed a 60m EFHW antenna for my home amateur radio station, see here and here.
The antenna has worked extremely well since then and using it I've worked stations on the 60m band as far away as the north cape of Norway and the Alicante region of south east Spain.
However the antenna, in common with all End Fed Half Wave antennas, has one drawback it has a very narrow bandwidth. To some extent the Antenna Tuning Unit (ATU) in my radio overcomes this but with the antenna set up to be resonant in the middle of the 60m amateur allocation the ATU struggles at the extreme edges of the band.
The answer is to have two antennas, one for the lower portion of the band and one for the upper. Well, not quite, I've rebuilt the feed-point impedance matching unit so that it is switchable using a relay to add some extra capacitance. The relay will be operated from the operators position at the radio using a multi channel remote antenna control system I've designed and built. This will switch between the two antennas, 60m and 80m, that share the same feeder coaxial cable and will also operate the tuning relays on both antennas.
The relay is in the lower right corner of the box with the small 10pF capacitor that it switches in and out of circuit just above it in the photo. The resistor and wire between the antenna and counterpoise terminals is part of the testing set-up to get the unit roughly tuned to the correct frequency.
The antenna has worked extremely well since then and using it I've worked stations on the 60m band as far away as the north cape of Norway and the Alicante region of south east Spain.
However the antenna, in common with all End Fed Half Wave antennas, has one drawback it has a very narrow bandwidth. To some extent the Antenna Tuning Unit (ATU) in my radio overcomes this but with the antenna set up to be resonant in the middle of the 60m amateur allocation the ATU struggles at the extreme edges of the band.
The answer is to have two antennas, one for the lower portion of the band and one for the upper. Well, not quite, I've rebuilt the feed-point impedance matching unit so that it is switchable using a relay to add some extra capacitance. The relay will be operated from the operators position at the radio using a multi channel remote antenna control system I've designed and built. This will switch between the two antennas, 60m and 80m, that share the same feeder coaxial cable and will also operate the tuning relays on both antennas.
The relay is in the lower right corner of the box with the small 10pF capacitor that it switches in and out of circuit just above it in the photo. The resistor and wire between the antenna and counterpoise terminals is part of the testing set-up to get the unit roughly tuned to the correct frequency.
For some time I've been meaning to place a barrier to unwanted RF (Radio Frequency) energy in the mains power supply to my Amateur Radio station. The object of the exercise is to prevent RF noise generated by local consumer electronics from getting into my receivers and masking the signals I'm trying to listen to. Also it should prevent stray RF signals from my transmitters being carried by the power wiring and causing problems.
A few weeks ago I actually bought the ferrite cores needed to do this and today I finally managed to build the choke into the power lead.
A few weeks ago I actually bought the ferrite cores needed to do this and today I finally managed to build the choke into the power lead.
Latest construction project
Feb. 15th, 2017 07:44 pmMy most recent construction project was the result of getting distracted from a distraction.
As a result I needed to be able to measure the, undesirable, common mode RF currents flowing on the outside of the coaxial feeder to my antennas.
I ended up building the meter described in:
http://www.ifwtech.co.uk/g3sek/clamp-on/clamp-on.htm
Here is the end result, in use you pass the antenna cable through the ferrite ring and the meter reads the magnitude of any current flowing on the outside of the cable.
As a result I needed to be able to measure the, undesirable, common mode RF currents flowing on the outside of the coaxial feeder to my antennas.
I ended up building the meter described in:
http://www.ifwtech.co.uk/g3sek/clamp-on/clamp-on.htm
Here is the end result, in use you pass the antenna cable through the ferrite ring and the meter reads the magnitude of any current flowing on the outside of the cable.
I found my first Geocache on 25th July 2002, today I found my 986th cache so I'm closing in on the magic 1000.
However, today was the day I completed my Geocaching calendar grid, I've now found at least one geocache on each of the 366 possible days of the year!
However, today was the day I completed my Geocaching calendar grid, I've now found at least one geocache on each of the 366 possible days of the year!
