4-First
Information for topics discussed on the local 4M nets
The 4m net discussions cover a wide range of topics of interest to the participants, and some of the supporting material and links will be provided here.
Colour on a monochome television
It's hard to believe, but the eye can be tricked into seeing colour in a monochrome (black and white display). This is caused by an optical illusion and one of the 4m net regulars remembers it being used in an Oxo advert. The video shown is from BBC Tomorrow's World.
Practical Television Magazine "Argus" Television Receiver
A number of members remember seeing examples of this project, that was published in March1952, for the Argus televisor, or television receiver. It used a number of war surplus parts, including a VCR97 CRT, used in wartime radar sets. Yes, it did have a green screen, and was small! A PDF document, describing the project in detail, by Dr. Hugo Holden is available for download here. A scan of the first page of the article in Practical Television is here.
Old Science Fiction
Often, we talk about old and new science fiction. Recently, Quatermass and the Pit has been a popular subject for discussion. Here's a treat for you...
Old maps and history in the Solent area
This has come up a few times in discussion on the net. Ordinance Survey maps usually contain much more detail than google maps. Items have a habit of appearing and disappearing, particularly those related to historic or military activities. "Site of ancient settlement" and "Battlefield" can be interesting, particularly in our local area. There are many shipwreck sites on the Hamble river, for example. A few maps show them, but most do not. There was a lot of interest in one of Henry VIII's ships, the Grace Dieu, which lies to the north of Bursledon bridge. More details on the Historic England site.
Power Supply Faults
There has been a lot of discussion around these. One problem is that when power supplies are switched on and off, they heat up and cool down. This constant heating and cooling may result in a dry joint. There is a good article on power supply fault-finding here, although it is aimed at computer power supplies.
Adhesives
Many of us use the UV-curing adhesives, but they have problems. The UV light has to penetrate the area to be glued together. Many of use use Gorilla glue, which uses a reaction with water to form a bond - useful for the cheap aluminium telescopic masts where the brass bush comes out of the collar. Epoxy resins are probably the best. One of the strongest is Marine Weld by JB Weld. It's available here (a small commission is paid if you buy from this link)
Radio, Radar amd Electronics Museums
Some museums that have been mentioned included Bletchley (of course), Beaulieu, Croome (National Trust in Worcestershire) and RAF Henlow. Some others are:
Amberley Museum & Heritage Centre, West Sussex
Royal Signals Museum, Blandford, Dorset
and here's a real gem in Kidderminster, here
The Internet and Routers
Everyone talks about this. Which is the best provider? Remember, there are only two infrastructure providers Virgin (part of Liberty Global, a US company) and BT Openreach. It's easy to switch providers using Openreach, but more complicated switching to and from Virgin.
Routers supplied by the internet service provider and usually not as good as the well-known brands. There is a good article here.
Meshtastic
Meshtastic® is a project that enables you to use inexpensive LoRa radios as a long range off-grid communication platform in areas without existing or reliable communications infrastructure. This project is 100% community driven and open source.
Features:
Long range (254km record by kboxlabs)
No phone required for mesh communication
Decentralized communication - no dedicated router required
Encrypted communication
Excellent battery life
Send and receive text messages between members of the mesh
Optional GPS based location features
And more!
How it works
The underlying technology, LoRa, is a long range radio protocol available to most regions without requiring additional licensing or certification, like radio amateur operators.
The radios automatically rebroadcast messages they receive in order to create a mesh network so that everyone in the group can receive messages - even from the furthest member. Depending on settings used, the Meshtastic mesh can sustain up to 80 device nodes.
Meshtastic radios can be paired to a single phone so that your friends and family are able to address a message to your specific radio. Each device supports a connection from a single user at a time.
There are two frequency bands used - 433MHz, where "ham mode" can be enabled, and 868Mhz in Europe. Most people in the UK are using 868Mhz.
More details at https://meshtastic.org/docs/introduction