Showing posts with label UHF. Show all posts
Showing posts with label UHF. Show all posts

Sunday, December 10, 2023

W5LUA gets first Worked All States award for the 903 MHz - 33cms band


Radio amateurs in the USA have access to an unusual band at 902 to 928 MHz which is known as the 33 cm band. Due to its unusual nature, much of the equipment for the band has to be home made or modified with transverters being a popular choice.

In November of 2023, Al W5LUA was awarded the very first Worked All States award from the ARRL. He started collecting the states shortly after the band opened in 1985 and his quest has taken 18-years.


As a band in the UHF region, most of the 'local' states would have been possible via tropospheric propagation but to work all 50 US states, signals had to be bounced off the moon. i.e. EME or moonbounce.

W5LUA's station consists of a 5-meter dish with 400 W of power obtained from two 300 W Motorola amplifiers in parallel. His feed is a dual polarity patch feed.


As recently as September of 2023, W5LUA was stuck on 32 states and still 18 short. Thanks to Peter, KA6U who went on a roving 25-state expedition, the last 18 states were worked.

W5LUA writes... "I am extremely grateful to Peter Van Horne, KA6U, for his EME [Earth-moon-Earth] efforts. I was able to work Wisconsin for my last state on the 33-centimeter band on October 21. At the end of September, I was sitting at 32 states confirmed with cards and/or the Logbook of The World (LoTW), when Van Horne went on a 25-state expedition providing my last 18 states.

W5LUA also notes that prior to that, recent expeditions by Brian, NX9O, and Jason, N1AV, also provided several states that were needed.

Background to the 33 cms band... In 1985, the FCC allocated the frequency band between 902 and 928 MHz to Part 18 industrial, scientific, and medical (ISM) equipment. In that proceeding, the band was also allocated to the Amateur Radio Service on a secondary basis, meaning amateurs could use the band if they accepted interference from and did not cause interference to primary users.



The list above from the North Texas Microwave Society gives an idea of what equipment is used on the band.

Links...
1) ARRL... The First Worked All States Certificate Awarded for the 33-Centimeter Band.
2) North Texas Microwave Society... 902 MHz Presentations (PDF)

Sunday, December 5, 2021

Guest Post: VHF & UHF operation... by Alan Johnson, VK3DXE

VK3DXE in Australia recently posted this article on his Facebook page and it is republished here with his kind permission to reach a wider audience. In it, he outlines what attracted him to the VHF bands.


I've been a member of a number of VHF/UHF Ham pages for a while, and keep seeing a lot of misconceptions and myths being picked up and quoted over and over by newcomers, and sadly a lot of not-so-newcomers who’ve brought their HF Game with them to the higher bands. 

I first became fascinated with VHF tropo propagation as a young kid living in the country, where we only had 2 TV channels, but occasionally we’d get the channels from the city suddenly appear when the conditions were right. You can imagine the excitement for a young kid way back then who's suddenly discovered some new TV channels! We had a neighbour up the hill who happened to be a Ham, and he explained to me how tropo worked. I was hooked, and from then on, whenever the weather forecast maps looked promising, and we got the right conditions, summer or winter, I’d start looking for the telltales that the city channels were going to pick up.

Fast forward 7 or 8 years, and I eventually got my Australian Novice license, quickly upgrading to the Advanced Call within a year when I was about 15 or 16. We were near the top of the sunspot cycle at the time, so I went nuts on HF for the next few years. But as the sunspots waned, I was drawn to the higher bands…..

As a youngster it was sometimes tough putting up a decent 2m yagi, but I always found a way of getting something in the air, and making the most of what I had available, even when living in rental housing. I just had to be creative, and sometimes a bit cheeky. The good thing about a 2m yagi though, was that even if anybody noticed it, they'd just figure it was a TV antenna.....  

You can build a small yagi like this in an afternoon with some simple tools.

I learned about aircraft enhancement in the days before we had all the funky tools we have today, before the widespread coming of the Internet. We managed to regularly make 2m SSB contacts of up to 700km (400+ miles) with smallish yagis and relatively low power - one path of 740km was quite good even with my portable station, with just a little 4 element yagi and Yaesu FT-290R II running only 2.5 watts!  

Living in inner city urban areas, I really began to appreciate low noise antenna designs (DL6WU & K1FO were the early leaders) and radio frontends that didn't collapse in the presence of strong out of band signals. I learned about GaAsFET LNAs (Low Noise Amplifiers, or preamps) too, and the importance of what was in front of the radio on RX. You have to think of your station as a system.

In the early 1990’s the Bible of VHF+ was published. The VHF/UHF DX Book very quickly became the must-have tome in every serious VHFer’s library. Although some of the chapters are now a bit dated, especially those relating to equipment, I strongly suggest everybody with even a fleeting interest in the higher bands downloads a copy and reads it. Hopefully it’ll help to undo some of the myths about VHF+ that have persisted in the hobby for far too long, things like the belief that troppo is only a summertime thing, and that troppo is the only worthwhile propagation mode on VHF+. Download it here: http://www.trpub.net/assets/applets/VHF-UHF_DX_Book.pdf

As the Internet came along and people developed all sorts of new tools, and we learnt about Forums, email reflectors, and then FaceBook pages, the opportunities to learn and collaborate grew amazingly.

Then the WSJT suite of software changed things overnight. All of a sudden, the little guys running just 100w to a 10 element yagi could successfully work stations on the other side of the world on 2m and above via EME, or Earth-Moon-Earth. I worked a dozen countries with just a single yagi and less than 200w at the antenna. 

Just last weekend, I was listening to HB9Q in Switzerland on 23cm for hours here in my /P shack while we're living in temporary accommodation, with a beautiful steady signal, often quite audible in the speaker, all on a tiny 60cm x 90cm gridpack antenna. 


Eventually, once I get my 2.4m dish in the air and find a suitable amplifier, I hope to be able to work him on 23cm SSB at home.... JT65 and Q65 will be an absolute walk in the park.

Lots of signals on 23cm with the gridpack.

In Australia, where we don’t have the population of Europe or North America, the Ham fraternity have embraced WSPR on 2m, and have demonstrated VHF paths of sometimes thousands of kilometres that no amount of listening to white noise for beacons or a coincidentally-timed CQ would find with the naked ear. Those paths are now being exploited regularly on digital modes, with people moving to SSB when conditions become strong enough. I've been around the hobby for a long time, but so too have the "old farts", some of whom vociferously decry the use of digital modes, but our experience here in Australia has really demonstrated how digital modes can be exploited to help get those SSB contacts that very probably would never have taken place otherwise. WSPR has been so successful that there are now WSPR beacons on Hawaii (often heard on West Coast USA), and in New Zealand, with a fantastic signal into East Coast Australia during the summer tropo season.

A little 4 element Cushcraft yagi. Even this is enough to decode some of the Big Guns off the Moon. I had many WSPR 2-ways with this one, out to 700km with Aircraft Enhancement

Next time you're asked by anybody (PARTICULARLY CHILDREN AND YOUNG PEOPLE) about the hobby, instead of trying to excite them with boring stories of talking on HF or FM repeaters, which they tend to equate with the equivalent of dialing random numbers on their cellphone to talk to old farts with bad combover hairstyles about their hemorrhoids, try telling them about stuff like all the space comms stuff we have access to, and can actively participate in, like using the repeater on the ISS, and all the other satellites we have access to. Tell them about Moonbounce, and how you can actually demonstrate the speed of light in action - you know exactly when the station on the other end has stopped transmitting, but can still see and hear his signal coming back at you for those additional 2 or 3 seconds it takes to travel all the way to the Moon and back. THAT gets young people more excited than listening to old farts! Try talking to them about meteor scatter, and how the military has used it for communication systems to counter the effects of comms satellites being wiped out in a conflict, or a dirty big EMP bomb wiping out HF. Tell them about aircraft enhancement, which is really bistatic radar, and how some clever dude worked out a way of using it to detect stealth aircraft by using commercial broadcasters behind enemy lines to illuminate the target. Tell them about all the really funky atmospheric and weather science they can learn just by playing with weak signals on VHF+. Tell them about the funky networking knowledge they can gain from modes like D-Star, IRLP, Echolink, etc. 

The /P shack while I'm away from home

Anyways, I've written this piece in response to a recent influx of newcomers and not-so-newcomers to the higher bands, possibly on the back of purchasing themselves a brand new IC-9700. I fully appreciate that everybody starts their learning journey from different places and has different interests, but some of the myths and misunderstandings I see are staggering. Unfortunately, so much of the Ham narrative has become very HF-centric, and that mindset often pervades discussions, and the marketing of the hobby, so this is just my little bit to try to counter some of that.  Remember to download the VHF/UHF DX Book from the link above, and jump onto some of the more technical pages and start learning. 

I'll be doing a bit of a write up soon on the importance of frequency accuracy and STABILITY on VHF+. Watch this space.

Enjoy!

de VK3DXE

Thursday, February 18, 2021

Video: Yagi Antenna talk by Kent, WA5VJB

Kent, WA5VJB recently gave a talk on Yagi antenna construction and designs for the UK Microwave Society and it is now on their YouTube page.

This talk should be of interest to anyone interested in building their own Yagi antennas for the VHF and UHF bands.

The talk lasts for about 38 minutes with a short 10 minute Q&A session after it.

WA5VJB also has his own website which has antennas and equipment for the microwave bands here... https://www.wa5vjb.com/index.html

Monday, February 8, 2021

Video: Unusual signals heard on the VHF & UHF bands with a radio scanner

 


As radio systems gradually migrate from analogue to digital technology, more and more unusual commercial and non-commercial signals can be heard on the VHF & UHF radio bands.

Lewis M3HHY in Manchester has a very popular YouTube channel where he puts up well scripted and presented videos about a wide range of radio related subjects. He recently put up two videos about some of the digital radio signals that can be heard on the VHF & UHF bands.

Video 1... 

Signals...

1) POCSAG ...Wide area paging.
2) MPT-1327 ...Trunk radio communication networks. 
3) Commercial DMR ...digital communications.
4) Car Key Transmitters
5) TETRA ...TErrestrial TRunked RAdio
6) Temporary Traffic Lights
7) Autocab ...Radio dispatch system
8) TPMS ...Tyre Pressure Monitoring Systems
9) Multitone Paging
10) dPMR ...Digital Private Mobile Radio (446 MHz)

Video 2...

Signals...

1) FLEX ...Flexible Wide Area Paging Protocol
2) VOR ...Very High Frequency Omnidirectional Range (108-118 MHz)
3) DAB Radio ...Digital Audio Broadcast
4) DSTAR ...Digital Smart Technology for Amateur Radio
5) NXDN ...Next Generation Digital Narrowband
6) Motorola Type II ... Paging Control Channel
7) Wi-Fi ...802.11N
8) System Fusion ...Yaesu Amateur Radio Digital Mode
9) LTE ...Long Term Evolution Network (4GLT / E-UTRA - Evolved Universal Terrestrial Radio Access). Mobile phone data.
10) AFSK ...Audio Frequency Shift Keying (Paging)

For additional information on unusual signals, visit this website... https://www.sigidwiki.com/wiki/Signal_Identification_Guide