Noises Off!

Radio frequency interference (RFI) is the bane of a lot of amateur radio operators. Sadly it is becoming a real issue at my QTH.

RFI is referred to as QRM or QRN and I am learning the difference.

QRM means “I being interfered with” and is interference coming from someone using radio equipment. This covers deliberate jamming, people tuning up or just normal operations on a crowded band that causes QRM.

QRN means “I am troubled by static” and technically means interference from a natural noises but has come to refer to interference coming from anything that is not an intentional radio emission and interferes with reception of transmissions. So now covers atmospheric noise, static or the noise generated by electronic devices.

Noise isn’t a new issue here as I have posted before. It has tended to be sporadic and bearable but since becoming licensed I have become more sensitised to it. Until now I have tended to focus on the VHF/UHF side mainly contesting venturing only briefly onto HF.

My HF set up is limited at the moment with just a single antenna which isn’t optimal for the lower bands. Due to the day job I am largely restricted to evening/night time operation when the upper bands have largely been closed anyway so haven’t really attacked HF with much enthusiasm apart from data modes such as JT65 and WSPR which have immunity to noise.

When I have got the chance for some early morning daytime operation or at the weekend I have struggled with noise.  Recent weekends have seen some special event stations operating for the Museums On The Air and the GB1JSS Summer Solstice which have been predominately on the 40M band but I just cannot hear anything on that band due to noise.

I am aware the Sun has been particular active recently producing a number of large flares and CMEs that have caused a number of radio blackouts, but this noise isn’t due to atmospherics I am certain it is man made by one of neighbours.

I made this video last weekend

and this video was from the weekend before that

This weekend was the 50MHz Trophy Contest which I was looking forward to, sadly it was also to become a victim of the QRN as this screenshot from my SDR will confirm, for much of the time I was operating I was just listening to noise.

I wasn’t operating constantly, just grabbing a few minutes here and there and I did manage to make some decent contacts when the QRN subsided even catching some of the sporadic E opening to get EF7X in Spain.

I have ruled out any noise being generated by myself by powering everything off and running on battery. This leaves me in a bit of a quandary I could go around and locate and confront the culprit or even contact OFCOM but at the same time I don’t want to antagonise anyone who could then object to any antennas I might want to put up in the garden.

Rotating the 6M Moxon around at the weekend during the contest as at least pointed me in the direction of one strong noise source. I am also convince that much of my problem is due to an evil PLT device in an adjacent property.

Following on from the weekend last night was the UKAC 50MHz contest and yet again I was troubled with noise leading to mostly local contacts.

I have been looking at some of the noise cancellers that are available from MFJ and others. I have heard conflicting options on their effectiveness but I am willing to try one if I can obtain one cheaply, or even home-brew one from the numerous designs available.

These devices work by using a second antenna which receives just the noise which is then mixed out of phase with the main antenna signal hence nullifying the noise. By all accounts they are tricky to use and often  need constant adjustment but may be my only viable solution at present.

Using the Ultimate3

I have dusted off the Ultimate3 QRSS beacon kit that I built earlier in the year while a foundation licensee. Having progressed to a intermediate licence I can now operate something I’ve constructed.

Until now it has been attached it to a dummy load with the FUNCube Dongle Pro+ SDR in close proximity as a receiver for experimental purposes.

One unresolved issue was it being consistently off frequency. The DDS modules used are prone to temperature fluctuations and component variances so the Ultimate 3 has the option of using a GPS module to provide both an accurate time source and an accurate 1PPS input which can be used to self calibrate. Except in my case it had proved to be unreliable.

I am using one of the inexpensive GY-GPS6MV2 modules containing the U-Blox chipset I posted about previously with the additional tap off to provide the 1PPS TTL signal.

Initially the GPS module was connected in close proximity to the Ultimate3 but struggled to maintain lock probably due to interference from the DDS module. Even when lock was achieved the calibration never seemed to work. I posted a question on the yahoo support group and from the answers I verified the calibration setting were correct so the only likely culprit was the quality of the 1PPS signal.

The serial NMEA sentences and the 1PPS signal from the GPS are likely to be required in other planned projects, such as an ‘shack clock’ and a GPS disciplined frequency standard. So I decided to put the GPS module  into a waterproof housing that can fitted on the shack roof in clear view of the sky and away from any potential interference. A multi-cored cable supplies power and the TTL RX/1PPS signals being fed back to the bench.

Sourcing an inexpensive weatherproof enclosure (£2) and waterproof cable gland were straightforward enough. I mounted the GPS module on a piece of strip board and replaced the on board LED with one mounted in the enclosure so I easily determine if the GPS had achieved lock, since it only flashes when it has. The LED is sealed with epoxy resin. It should be noted that the outputs of the U-BLOX chip are only rated at 10mA so bear it mind when selecting an LED and calculating the current limiting resistor. The connecting cable is some surplus unscreened alarm cable fitted with a couple of ferrite clamps.

The GPS now has no trouble achieving lock and quickly sets the Ultimate3 clock. Researching the 1PPS problem I hadn’t come up with anything definite, as the signal looked okay on the oscilloscope. But I decided to fit a 10K resistor pull up resistor between the 1PPS output and the 3.3V supply on the GPS module. If this actually made the difference I have no idea but the Ulimate3 now successfully calibrates the DDS using the GPS.

At the moment I have configured the beacon to run WSPR and I have been spotted by other operators. Initially I wasn’t getting much RF out of the device and it turned out to be a combination of poor connection caused by me not removing the enamel properly on a toroid winding and an iffy antenna connector. Both have been corrected and now get a measurable deflection on the SWR/Power meter. With the additional of a second power amplifier FET it is around 200-250mW.

I purchased the Ultimate3 with a low pass filter for the 40M band and while I have had some European spots the results have been a little disappointing. 40M has turned out to be almost unusable at my QTH due to QRN/M so not sure if that is having an effect, also the antenna I have isn’t naturally resonant on 40M so is going through a tuner which will certainly be introducing some losses, without the tuner the FETs get very warm!

With this in mind I have purchased some additional LPFs for the 30M and 20M bands and the LPF relay switching board for the Ultimate 3 so can try/run multiple bands.

144MHz Backpackers Contest

I had a great time today competing in the 2nd RSGB 144MHz Backpackers contest. I entered the 10W Hill Toppers (10H) section since I could operate from the comfort of the car and I could use the FT857 as the Hill Toppers section in the RSGB contest allow operation up to 10W.

The Backpacker (3B) section and the concurrent Practical Wireless 144MHz QRP Contest are limited to just 3W. Normally the FT857 can only be lowered to 5W but by applying a negative voltage to the transceivers ALC line via the accessory socket the transmitters output can be lowered. This method is detailed here it is a simple circuit and I will make one up in due course, I didn’t have the parts to make one in time.

Anyway I digress, firstly I had to find a suitable hill top that wasn’t too far from home. I wanted somewhere quiet and minimised the risk of any confrontation with societies undesirables. A quick look on the local Ordnance Survey map and I spotted a viewpoint symbol.

1:50,000
1:25,000

It isn’t exactly a mountain at just 82m above sea level but is nearby and seemed quiet when I drove out to inspect it. It is the Maplebeck View Point and has a metal plate highlighting hills and structures that can be seen from the ‘summit’ sadly the overgrown hedges did limit the view but it did seem a decent spot with an off road parking area and picnic tables.

The viewpoint
The information plate on the viewpoint

I now needed to sort out the equipment. Operation from a motor vehicle is permitted but all equipment used during the contest must be battery, wind or solar powered. So I made a trip to grab the spare leisure battery from our caravan and the cast iron parasol stand to act as a base for my pole, the antenna would be the Sandpiper 3 element Delta Beam I used in the Lake District.

battery wedged behind drivers seat
Parasol stand and painter’s telescopic pole
Operating from the passenger seat, FT857 on dashboard
Antenna up

I had the FT857 on the dashboard and sat in the front passenger seat, the pole was within easy reach out the window and I had fitted a small pointer on the pole so I knew which way the antenna was pointing, so could turn it by hand.

I was initially quite nervous setting up as it turned out the road was actually quite busy and I was getting a lot of quizzical looks from passersby, but once I got going I just ignored them and enjoyed the contest a lot. A number of walkers asked what I was up to and it seemed the viewpoint was a stop off on a MG owner’s outing this morning.

I made a reasonable amount of contacts, given most people were operating QRP with some decent distances. I did suffer one brain fade and missed another potential locator square when the other station repeated my report back and I blindly wrote it down and then lost them before I was able to correct it.

At one point I thought I would have to pack up as I was getting huge static crackles and pops which were due I think to some nearby high tension electricity pylons and what appeared to be a gathering storm, there was some brief rain but it quickly dissipated.

Next month I am looking forward to the VHF National Field Day and the 3rd Backpackers Contest as a number of members of the South Kestevan ARS are keen to have a serious attempt.

Planning some more /P and /A

All too quickly and the holiday is over

Apart from the UKAC on the Tuesday night I didn’t do anything else with the radio, I did have the HF antenna up but the trapped nerve in my back meant I was in a lot of discomfort after being out and about during the day and so rested and zonked out on painkillers rather than struggling to set up the rig.

I must sort out a proper portable station that I can just open it up and start operating, I am impressed with Charlie’s M0PZT porta-pack frame idea being an excellent solution especially for back packing.

In the past the wife and I used to be keen walkers, tackling many of the peaks in Cumbria, Snowdonia, the Peak District and elsewhere. We completed the Coast-To-Coast Walk back in 1991 and The Cleveland Way the following year.

Dipping my boots at Robin Hood’s Bay in 1991 at end of the Coast-To-Coast

Sadly I am too overweight now to be a serious Summits On The Air (SOTA) operator but I plan on getting back to a reasonable level of fitness. As it happens if I’d been more prepared our walk of Latrigg last week could have been my first Wainwright On The Air (WOTA) activation.

Next month we are off to the Isle of Skye. We are staying in a self-catering cottage with plenty of room so rather than being /P portable I can be /A alternative and will be able to set up the rig in the cottage so can use it as and when I want.

I’ve already mentioned the holiday coincides with the 50MHz/6 Meter UKAC and am currently toying with the antenna choice, one advantage of being so far North is I won’t need to rotate it as pointing it South South East should cover most of the UK. From the photographs of seen the cottage is reasonably elevated with clear views across Loch Bay in that direction. There are mountains ranges to contend with but who knows with propagation? I’ll be in the rare IO67 locator square so might even have to contend with a pile up!

I will almost certainly operate as 2E0NRD rather than M6GTG for that week as using just 10W might be a bit optimistic.

IO67 Locator Square

I got somewhat excited last week when I received an email announcing the RSGB First 50MHz Contest results I was down in 35 place in the SF section but with a rosette next to my callsign? Wow I’d got an award! Pleased with myself I jumped on twitter to spread the news…

Gobsmacked.. pic.twitter.com/sGDI4jDh1W
— Andrew Garratt M6GTG (@nerdsville) June 7, 2014

Perhaps I shouldn’t have been quite as quick to brag as it appears I was the only Foundation Level entrant!

Still I managed 4 verified QSOs on what by all accounts was a very difficult contest, with low activity and poor conditions. In fact I almost missed the contest altogether and was only alerted to the contest by a tweet by Robert @G1ZJP and was late starting as I needed to get the antenna up. I actually made 5 QSOs but one was broken because I mistakenly put 59 in as the serial number.. Doh!

This weekend is the 2nd RSGB 144MHz Backpackers contest and the Practical Wireless 144MHz QRP Contest Unfortunately the FT857 is too powerful for the QRP contests as the limit is 3W but I could have a go at the Hill Toppers section in the RSGB contest which is limited to 10W and as luck would have it I am left to my own devices this weekend so might take a drive in the car..

M6GTG/P The results are in!

Last nights 144MHz UKAC Contest gave me the opportunity to try operating portable for the first time. Caravanning in the Lake District just outside the town of Keswick I had spent the previous evening preparing (see earlier post) and after a day out walking I set up the station in the awning.

I hoisted the 3-Element Delta Beam to full height and waited for the appointed time. The campsite was very quiet but I still attracted some strange looks as people wandered past!

In the end I struggled only making 6 contacts, I searched and pounced initially and then called CQ for a time with no response. The caravan site has a strict no-noise policy after 22:30 so shutdown and packed up just before 22:00 Despite the low number of QSOs I wasn’t disappointed, given my location and low power (10W) I was glad of any contacts.

Earlier in the day my wife and I took the dogs on a walk to the top of Latrigg which is just to the North of the campsite and is one of the lowest fells in the Lake District at 381m asl. From the summit we could clearly see the campsite below at just 218m.  So perhaps not the best spot to be operating from, being surrounded on all sides by mountains.

Next month I am away to the Isle of Skye for the UKAC 6m contest, encouraged by the Delta Beam I might have a go at constructed one for then (if the wife agrees)

In the meantime I have got the magitenna up for HF but haven’t used it yet after all I am here on holiday and have to spend time with the wife and dogs!

Just a correction in my earlier post about passing my intermediate I neglected to acknowledge the help of Nigel (M0CVO) and SKARS for the assessments and organising the exam.

First time working portable

Have taken one further step up the amateur radio licensing ladder, passing the Intermediate exam and assessments. A big thank you to Grantham ARC and Alan and Keith for invigilating and congratulations to my fellow candidate Mark Orbell who also passed.

My new callsign is 2E0NRD

Current QTH

I am currently writing this blog entry while on holiday sitting in the caravan watching the sun rise over the Lake District. I have brought the rig along with a M0CVO magitenna for HF and not wanting to miss out on the 144MHz UKAC tonight have a Sandpiper 3-Element Delta Quad.

It has already caused some strange looks on the campsite while I built it up and tested it last night and I hope I won’t have any RFI issues as caravans are often fitted with wideband TV amplifiers! Thankfully the site is currently very quiet as the school holidays have finished.

Testing the Delta Quad last night

Initially was going to make a Moxon for 2m but I messed up my first attempt and ran out of time to make another so at the last minute ordered the Delta Quad from Sandpiper. It is a well built antenna I just had to cut the three loops and solder them up, the instructions were very clear. It is easily dismantled and seems ideal for portable work so is an investment for the future.  I hope to use it during July’s VHF NFD.

The antenna has an excellent VSWR match and when testing I clearly heard a cw/jt65 beacon around 144.480MHz which must have been GB3NGI on the Slieve Anorra Mountain in County Antrim, Northern Ireland (IO65VB)

I will be operating as M6GTG/P tonight as don’t want to upset my UKAC scores and I am not really sure what to expect as surrounded by mountains in most directions here but should be fun. I might even rope in Boris to give me a hand

Boris not looking too impressed

Last Tuesday (27 May) was the 50MHz UKAC. I had intended to do some operating over previous Bank Holiday weekend and with reports of Sporadic E propagation picking up on 6m I had put my homebrew Moxon back up on the pole with the new rotator. Unfortunately the operating was curtailed due to the discomfort I am currently suffering due to a trapped nerve in my back.

That weekend saw some horrendous weather and it rained heavily for several days, indeed it had rained most of Tuesday, checking the VSWR in the evening before the start of the contest I was shocked to see it had risen from 1:1.5 to nearly 1:3!

I knew the bad weather was forecast before putting the antenna up so had made sure all the coax connectors and the feedpoint were properly sealed with self amalgamating tape so was somewhat perplexed. In the end I decided what I thought the issue was, the moxon frame was untreated softwood and in the bad weather had become very wet and damp and suspect it was affecting the resonance.

Despite this I decided to carry on as I was only running 10W and had a productive few hours despite some local noise.

I
27 May 2014 – M6GTG 50MHz UKAC QSO Map

Anyway time to put the kettle on and I will post an update about how I get on tonight.