VDSL QRM – Not Just an obscure problem!

After reading the May 2020 and September issues of RadCom, it became clear that almost all radio amateurs have been suffering QRM from VDSL, some without knowing it! The problem is that the transmission type is broadband and not the sort of QRM you can readily identify. It just raises the noise floor and obscures weak signals! However, help is at hand. To this date Ofcom has not done much about the problem because there have not been many complaints from radio amateurs. The May issue of RadCom is a Call to Arms!

The article details software (free from the RSGB) called Lelantos that has been developed to identify and measure the relative strengths and spectrum of VDSL2 RFI.

While some amateurs might be reluctant to learn to use the software and don’t have the necessary SDR at hand, one of our club members has the software and the SDR ready to use and can come to your QTH to make the VDSL check for you! These recordings can be made from your driveway or front of your house without connections to your house or shack.

The results will be passed on to you with the info necessary to make your own submission to OFCOM. This service will be free to all members and even other radio amateurs in our catchment area! Look out for an email coming your way to let you know how to contact the person making the measurements. The actual operation only takes about ten minutes of your time and could help save Amateur Radio for now and the future.

You can read the entire story in depth here: http://rsgb.org/main/files/2018/10/vdsl-RFI-Impact-interim-report.pdf

While it looks like the RSGB is doing lots of work on this, OFCOM will only be moved by reports from more than a few radio amateurs.

Due to Covid 19 and the attendant problems facing gatherings, especially by older persons. Our club meetings have been suspended until further notice.  Please check your email weekly or more often for updates.

During the Club’s shutdown, each Thursday there will be a club net on 2 Metres at 20.00 BST Starting on 145.50 and moving to an empty channel.  In addition, there may be  a 160m ‘Top Band’ informal  meeting  each Mondays at 19.00 BST on 1.985, SSB

All members and visitors are welcome.

Brian began with a short biography of founder Frank Winfield Woolworth born 13 April, 1852 in New York. In 1879 Woolworth borrowed $300 and opened the first five-cent store in Utica, NY, Unfortunately, it failed within weeks!  His second venture was in April of that same year when he opened another store in Lancaster Pennsylvania where he expanded the concept to include merchandise priced at ten cents.

Frank expanded into the UK market by opening his first UK store in Liverpool, the date was 1908. Brian detailed significant points in the company’s progress by playing records that were on sale at the time, starting with an acoustic recording supplied on a five inch disc which sold for six pence. Through the years many recording companies served the Woolworth market with records by ‘not so popular’ artists sounding like the records at the top of the Hit Parade. They were still selling at a marked down price.

The company survived most of the problems faced during the years, but lost out during the 2008 banking crisis, and with falling sales the company went into administration.

The discussion included Wi-Fi as well as HF radio communications. Types of aerials and modes, old and new were topics for discussions while tea and biscuits were served.

This evening the members watched a video from the RSGB 2018 Convention Lectures  series. It can be found on the RSGB website (or YouTube). Just search “an introduction to 3D printing for the radio amateur  by James Patterson, M1DST”

While the technique isn’t new, it’s not a field many of our members have ventured into. A copy of the wrench that was printed on board the Space Station was passed around for inspection.  The files needed to produce this and many other items are on the internet for general use without charge.

Members arraigned the chairs in a circle around some tables and had a general discussion.

While free tea and biscuits were served, members discussed various topics including propagation, wind loading on masts in strong winds and computer problems.

First up was Rob, M0IXM. This was his first entry into our contest with his Capacitive Touch CW key. The original design was published by M0UKD on his website.  The board is rather small and uses surface mount components. The board details were published on the website and Rob sent the Gerber files to China (where else!) and had several boards made. Using a hot air paint stripper, Rob was able to solder the parts on to the board, however, he found that too much air blew the parts off the board and resulted in starting over. He also found that trying to find the pin one on the ICs needed more power than his magnifying glass could provide, so he resorted to a stereo microscope, which worked fine. Rob was able to demonstrate the key’s use when connected to Alan’s QCX CW transceiver,

The winner of our Kit Class was Alan, G4PSO who built the QCX 5W CW transceiver. This is a one band unit and Alan chose to use 20M. Alan explained he bought the kit two years ago but didn’t make a start in building it, mainly because he spent a good while last year visiting New Zealand. He started by downloading the instructions from the internet, all 141 pages of it!  Rather than printing it out, he opted to read it on his tablet.  He did show a digital video version to members to show how much detail there is on offer to the builder. Alan explained the finished board can be used as a volt meter to measure various points on the board to confirm proper operation. The board also contains a Signal Generator, a CW reader and a method of measuring power out. Lot’s on offer from such a small board.

Don, G4LOO won the Weekend Special with a project that seemed more than a week end’s work. It was a Test Jig to enable testing the pin in and out of the Racal amp control boards he wanted to make use of in his 23cm 500W linear amplifier.  He had several surplus boards and wanted to test to find one that actually worked.  The end product ended up in Don’s Major Project winner. This project started life as an ex TV YD1336 cavity, modified as per Dubus article by G4DZU.  It was said to tune 70/23cm. Included was a valve with a slightly bent anode cooler, which proved to be unusable due to cracks in the ceramic base. The cavity was supplied without fan, chassis or circuits. Don provided the main case and everything needed to support the cavity. The finished project required a fan capable of producing much more air flow than usual,  2.5 cubic meters per second, to be exact!  The required control, monitoring and reporting is carried out using Arduino boards and the results are displayed on the separate control box.

This evening’s programme was meant to follow the live demo of FT8, however, since the person giving the demo was called away, the demo will be moved to another evening.  All of which means this evening’s planned programme needs to be held over till we have seen the demo. To that end, the assembled group of members decided to watch another video instead.

Unfortunately, the video which looked to be the most interesting, turned out to be less than expected. The presenter held up various items which we couldn’t make out and there was never a description.  Most of the presentation was two views side by side on the screen of which the view with the technical details were presented in lettering too small to read from the second row in the auditorium. There were some questions as to the validity of the earthing system being proposed as the best to use in the shack.  All in all, a bit of a disappointment.

It’s always amazing what members have been working on during the past year and enter in the Annual Construction Contest.  A good turnout for the evening provided the judging panel and the winners were:

Novice: (a class for any member’s first entry into this contest) was won by Rob, M0IXM with his submission of a touch sensitive CW key using surface mount components.

The Weekend Special: was won by Don, G4LOO who made a Test Jig to enable testing of the pin in and out of the Racal amp control boards he wanted use in another project.

The Kit class was won by Alan, G4PSO who submitted a QRP Lab QCX CW transceiver.

The Major Project was won by Don, G4LOO with a truly ‘Major’ project, A 500w 1296MHz Linear Amplifier.

The cups and plaques will be awarded at this year AGM on the 19th of March.

Since our speaker had been unexpectedly called away, the promised FT8 demo will be given at a later date. To help members know what they will be looking at, it was decided to have an evening introduction to finding and installing the programme, as well as a look at what is being displayed and how you might set it up.