Antennas start to come down and wi-fi range tests

Today marked the beginning of the end for amateur radio at the present QTH. We've lived very happily here for 37 years, bringing up our 2 boys and welcoming our 4 grandchildren. Now we are just a few weeks away from our move to the bungalow 300m away up on our local "hill" next to the windmill, the latter currently undergoing a £417k refubishment courtesy of a National Lottery grant. The new home is a nice place and we are looking forward to the move, but it won't be without a few sad moments: closing a chapter in our lives but also opening a new one. The last time we moved, the removal van cost just £11 - it was a LONG time ago, HI.

Today I removed the first part of the antenna system: my 20m spaced earth-electrode wire running in the back garden. Next to come down will be the coax feed from my workshop to the upstairs shack where I operate. The V2000 vertical and the Par 10/20/40 end fed will come down in a few weeks time. I also de-cluttered the bedroom shack to some extent, clearing out all manner of the "I may need this some day" rubbish that fills drawers and cupboards. It is just unbelievable how many SMPSU wall blocks I have that belonged to equipment like routers and scanners long gone. The worst is always the stuff you've kept because, "I may need this one day".  I am trying to be ruthless and give it to a local charity store, recycle centre or the dump if it has not been used, read, looked at for several years. For certain something that goes will be needed next week.

I did a test at the new bungalow tonight on the internet wi-fi coverage: I took my Virgin Media wireless super-hub and set it up (locally, no internet connection) and walked around the new home with my iPod Touch 4g to see how strong the signal was in the shack, bedrooms and garden. Results were promising: I think I may get away without a range extender.

WonderLoop antenna

If you have just bought a copy of the August 2013 copy of Practical Wireless you may have noticed that in the next edition (September) I'm doing a review of the WonderLoop antenna, although the editors managed to give me a new callsign by mistake in the "Coming next month" column on p77, HI.

Confidentiality prevents me saying anything yet until the edition is published, but I much enjoyed carrying out my tests.  I have absolutely no affiliation with the manufacturer or supplier. As a keen blogger I find it hard not to blog about something radio related that I have played with!

The Wonderwand page is at http://www.wonder-wand.co.uk/WonderWand/WW_Homepage.html .

If you are interested in reading my review, please buy the Sept 2013 copy of PW on sale August 8th.

Birdlip in the Cotswolds

The distant Malvern Hills from near Birdlip

There have been no posts for a few days as my wife and I have been away from home staying a couple of nights on the western edge of the Cotswolds at Birdlip. The occasion was a gathering with cousins I'd not seen for around 50 years. The gathering was excellent. We stayed at the Royal George Hotel (3 star rating) which was superbly located right next to the Cotswold Way path with good rooms, large gardens and excellent value meals.  I am please to report that everyone had a great time and got along fine!

This part of the Cotswolds would make an excellent VHF-microwave location with the Cotswold escarpment meaning the ground falls away dramatically towards Wales and the west. I didn't take any radio gear, but will do so if I stay there again. The hotel was a good find.

472kHz in Canada - getting closer

From Joe VO1NA:

Dear Group,
Last week, Industry Canada published its Proposed Revisions to the Canadian Table of Frequency Allocations. It includes the 630m band for the amateur service.  So we wait with much anticipation...
73
Joe VO1NA

VHF/UHF QRP DXing with weak signal digital modes?

When there is a decent contest with some portable stations with decent antennas about, it is surprising how far can be covered with QRP kit on 2m and 70cm. This makes me wonder just what sort of ranges could be covered with QRP and modest antennas on these bands using WSJT digital modes.

Going from SSB to one of the more effective weak signal modes is like gaining another 30dB, i.e. far more that the antenna gain of a big contest station, suggesting that ranges of 200-300km should be ALWAYS possible on 70cms with quite modest QRP stations with small yagis or colinear vertical antennas in flat band conditions.

I am speculating what sort of ranges should be possible under flat conditions (no lifts) with 5W and a small omni or broad beam yagi such as a Moxon or HB9CV.  When I move to the new QTH I think some 70cm skeds are called for with stations out to 300-400km using WSJT modes using 5W or less.

70cm VHF NFD with a simple QRP station

4 ele 70cm yagi on car

Just for a little fun in the sunshine I took my FT817 and "coathanger" 4 el yagi onto a local high spot (actually nothing is high here in East Anglia!) to try just over an hour of operating on 70cm SSB during VHF NFD. Conditions were average, but I heard EI, F, GM and PA and worked 12 stations in just 70 minutes of casual operation with the best DX 262km.  Power output was either 2.5W or 5W.

The 4 el yagi is mounted on a 22mm PVC pipe mast that is simply wedged in the car rear window and manually rotated. The whole set-up can be erected and taken down in about 2 minutes: I don't take contests THAT seriously you see :-)  The map shows the stations worked before going back home for tea.

70cms QSOs in 70 minutes with 5W to a 4el yagi

After tea I parked the car outside my new QTH and erected the 4 el as shown in the photo. Signal strengths from DX stations (PA0 and a station in SW England) were very similar to those on my local /P site, suggesting the new QTH, on a local bump, is promising for VHF/UHF/microwaves.

70cm is a great band and sadly under-used these days on SSB. It is also sad that there are so few 70cms beacons on the air in the UK now. I believe the Bristol 70cms beacon - it was a good conditions indicator here in East Anglia - has recently gone QRT too?

30 line TV

It is a long time since the Baird 30 line TV system was replaced by 405 line and then 625 line TV here in the UK. However, there are still enthusiasts building mechanical 30 line TV systems and getting respectable results. At one time I joined the NBTV group (does it still exist?) who promote(d) hobby activity with 30 line TVs, particularly mechanical versions with scanning discs etc. Bandwidths needed for such systems are very narrow (audio) so the signal can be transmitted using a standard voice transmitter. These days it is possible to produce 30 line TV using a PC, but this not quite the idea: one can after all communicate worldwide by Skype video or FaceTime.

 This video (linked from its original location on You Tube) gives some idea of what is possible.

Wellbrook LF RX Loop

http://www.wellbrook.uk.com/antennashop/image/cache/looponfence-250x250.jpg

A Wellbrook ALA1530 loop antenna for VLF-HF reception is now in my plans for the new QTH. This is not a low cost antenna - currently around £200 in the UK - but its performance is excellent judging by reports from people I know and reviews. It looks like the very best choice of RX antennas for the 136kHz and 472kHz bands where local noise can be a real issue. It does not need to be mounted high, just about 5m from the house. The photo above (linked from the Wellbrook site) shows the antenna mounted on a fence.

The technical specification speaks for itself: truly excellent OIP2 (+90dBm) and OIP3 (+49dBm) figures and a 1dB compression point of +28dBm in the Medium Wave band. It can stand a local field strength as high as 400V/m. As a loop, this antenna has a figure of eight pattern, so local noise sources can be nulled in many cases. It covers from 20kHz to 30MHz.

This looks like a good investment before the LF DX season.

VLF kit at PA3CPM

Henny PA3CPM has been continuing his 8.270kHz VLF transmissions, on and off, for some weeks now and is getting reports from several stations in western Europe despite his modest antenna. Paul Nicholson in Todmorden and Eddie G3ZJO regularly receive his signals using integration over several hours and extremely narrow bandwidths to dig the signal out of the VLF noise.

8.270kHz VLF loading coil at PA3CPM

This is a photo of Henny's huge loading coil used to bring his 40m sloper to resonance on 8.270kHz. The loading coil uses a LOT of wire (several kms) and building such a VLF loading coil is not for the faint hearted! I suspect that a large wire loop may be an easier TX solution?

PA3CPM's VLF PA unit

Henny is using a 200W PA and this is shown here. Note the fans to cool the unit.

To radiate an amateur signal at VLF requires special dedication, yet Henny has shown that even a modest 40m antenna can get a signal hundreds of km on VLF with quite modest powers. It is indeed a new and exciting area of the hobby.

Analysis of the PA0RDT E-field probe RX antenna

Image of miniwhip on VK1OD's website

VK1OD has done an interesting analysis of the PA0RDT E-field probe miniwhip receiving antenna. This is very popular as an effective antenna from 8.9kHz right through to the HF bands. I have used my own versions on the VLF, LF and MF bands with great success, but I commend the PA0RDT design to you. His design uses readily available semiconductors to give excellent IP2 and IP3 figures. You may be surprised how something this tiny and simple can work so well if mounted away from the house on a small pole. Remember, you do NOT need big antennas to receive on the lower bands: it is S/N that matters not very low noise figures. VK1OD's analysis is somewhat harsh: in my view it works as a true E-field probe should, even at VLF.