rinioth: (weeme)
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!
rinioth: (weeme)
At 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.
rinioth: (radio)
I 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.
rinioth: (weeme)
Can you spot me? This was taken in 1959 when several of my cousins were visiting for the day!


Apr. 14th, 2017 08:50 am
rinioth: (radio)
stuck SCAMAfter 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).
rinioth: (Default)
Since 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.
rinioth: (radio)
About 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.

switchable EFHW unit

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.


Mar. 14th, 2017 02:56 pm
rinioth: (radio)
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.

Mains Choke
rinioth: (radio)
My 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:


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.

RF Ammeter

366 / 366

Dec. 12th, 2016 11:32 am
rinioth: (weeme)
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!
rinioth: (plane)
Last weekend was the G-QRP Club Convention weekend in Rishworth, Yorkshire.

The G-QRP Club is the British low power Ham radio club, each year they meet up for a weekend for a time of socialising, building a project and attending a flea market type rally with a couple of lectures thrown in. I've been for the last 4 years and always enjoy myself.

This year the buildathon project was a Solar powered 80m CW transmitter with an output power of 20mW (yes, 20 milliwatts!).

The solar panels are from garden Led lights and provide just enough power to charge the batteries during the day for an evening of operation. The transmitter is very simple, just one transistor in a Pierce oscillator circuit followed by a low pass filter.
rinioth: (radio)
A few weeks ago I was reading one of the Vintage Wireless Forums that I look into occasionally and someone was talking about the "Heath Robinson" radio he had built from junk parts he had laying about in his workshop. The idea appealed to me and after a brief rummage through various boxes I came up with enough parts to build this:

Heath Robinson AM Rx

Even the base board is a piece of scrap peg board. The valve (tube for you USians) is a double triode of which I'm only using one half. The power transformer is about 10 times the size it needs to be - but it was in the junk box so I used it. The yellow socket in the middle of the coil is where the antenna plugs in and it quite happily pulls in a number of AM Medium wave radio stations. The basic circuit is a simple regenerative one with the minimum number of parts. From left to right the parts are: The power transformer, the rectifier and smoothing capacitor for the HT, the Headphone socket, the ECC81 valve, the main tuning capacitor, the coil with the (blue) regenerative winding over one half and finally the regenerative variable capacitor. There are a couple of small parts that are not visible in the photo.
rinioth: (radio)
One of the Ham Radio related things I do is to act as a QSL (confirmation) card sub-manager for a small group of UK callsigns. This means that 3 or 4 times a year I get sent a box of cards which have to be sorted into callsign order. The owners of the calls provide me with pre-stamped envelopes and when an envelope is full I send it back to them.

A box of cards turned up this morning and I've done the initial sort into 12 alphabet groups for the bigger series I deal with and a single pile, visible at the back, for the smaller series.

Over the weekend I'll re-sort each pile and merge it with any cards I already hold which are either awaiting the arrival of envelopes or for calls where the envelope wasn't full.

The whole purpose of the 'bureau' system as it's known is to make it much cheaper to send the confirmation cards around the world since the system batches them up, it's almost entirely run by volunteers.
rinioth: (plane)
Martha is now just over a year old, so it's time for more photos!

Books are one of her favourites!

and so it seems are hats

and more interested in the lights than the actual ride it seems
rinioth: (plane)
I've made a start on replacing the capacitors in the Sobell Radio. The original electrolytic ones were in aluminium cans and by carefully cutting the can open around it's seam and removing the failed innards it's possible to fit a modern replacement inside. This is helped by the replacements being considerably physically smaller due to advances in technology during the last 70 years!

rinioth: (plane)
The radio is sort of working. After powering it up using a variac to very slowly bring the mains power up to the nominal voltage the radio actually produces sounds from various medium and long wave radio stations. The short wave side of it doesn't appear to work yet though.

Things are not right in some areas, most notably some things are running warm/hot that shouldn't be. This is almost certainly due to leaky capacitors. I've decided to spend at least a little more time on it so the next job is to source replacement capacitors for the faulty ones.
rinioth: (plane)
The Sobell chassis is now out of the cabinet and has had a thorough clean with the vacuum cleaner, a damp cloth and an old toothbrush. I've also cleaned the cabinet up a bit although it will need more work.

The chassis doesn't look too bad on top, but the underside shows a lot of evidence of a very hard life. There are several very blackened components, caused by overheating and some very suspect looking replacement wiring in the HT part of the power supply.

Before I go too much further I will have to evaluate what represents a reasonable level of restoration. The sets are not rare and even working ones are not very valuable (maybe £20) so unless I want to use it as a deep restoration learning exercise it's probably only going to be a "get it safely working" project.
rinioth: (plane)

I've been doing a lot of radio related restoration work recently. This was due to helping the relatives with the clearance of equipment from a deceased radio ham's house.

Most of the cleared equipment has been, or is being, sold with the proceeds being given by the family to the local radio club.

They expressly asked that as little as possible of the equipment was 'skipped' they would prefer it to go to a good home as a gift instead.

One of the items is a 1945 era mains powered radio by the small radio company "Sobell". Their Model 615 radio was a mistake, it is technically fairly standard for the immediate post war era but they built it into a very large (22" x 16") 1930s style wooden cabinet which turned out to be overly ostentatious for post war austerity.

None of the local radio hams was interested and so I've been working on it myself. Under 70 years of dirt and dust it's in reasonable condition, there were some valves missing, but I've replaced them from my stash.

The back cover is missing, the original would have been made from 'hardboard' so fabricating a replacement will not be difficult.

The mains power lead has crumbling rubber insulation and looks lethal and so that will have to be replaced before I start testing. The set also appears to have been "got at" a little, which is inevitable for one owned by a Radio Ham but nothing that isn't fixable.

It is surprisingly easy to find the technical data and circuit diagrams for domestic equipment from that era and equivalent parts to replace failed components are not difficult to source.
rinioth: (radio)
On the 23rd of April I took part in International Marconi day. This is held each year on the Saturday closest to his birthday (25 April 1874) to celebrate the huge part Guglielmo Marconi played in the invention of radio.

There is an award certificate, based on an original Marconi Stock Certificate Circa 1901, for those who manage to contact 15 or more of the special stations that are on the air for the event. I spent several short periods on the radio during the day and managed to work 20 of the stations.

I posted off my contact log and my certificate arrived in the post today.

IMD Cert
rinioth: (weeme)
This morning there was a heavy frost.

Now the garden is white again this time with hail.


rinioth: (Default)

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