If there's one thing for sure, it's that understanding propagation on 12m is poor because there are far too few stations using WSPR on that band.
Last evening, I started WSPR using my 3-ele LFA Yagi pointed at central Europe. I was amazed to hear - and be heard by - stations in Italy, Germany and the Netherlands. These weren't faint traces but full-on, band-wide-open strength signals - lasting up until local midnight!
There's been quite a lot of discussion about bands only being closed when you believe that they are. And I couldn't agree more. The internet and its many clusters has only made things worse, in that if the band is not being reported as open, others follow like sheep and go elsewhere.
Here's to more 12m WSPR stations opening up soon!
Monday, 18 July 2016
Friday, 15 July 2016
Keyboard RFI - WTF?
Having recently sorted out some LCD screen RFI by replacing a new model with an infinitely quieter, older one, the RFI problem has become a headache again!
You know the feeling: RFI and you really, really want to sort it out. After ages of getting nowhere, I started using a simple battery-powered AM radio to detect what was making noise.
This proved a very powerful system! Almost immediately, I could detect very strong RFI coming from a cheap HiPoint keyboard that I'd moved from my Raspberry Pi for use at the rig.
The sheer level of RFI this small keyboard produced, despite having a metal base that might have made it well earthed, was incredible!
Replacing the keyboard with a standard curvy Microsoft unit instantly resolved the problem, and restored radio-quietness to the station! There is now no materially significant RFI from the recent changes to an external microphone and external screen and keyboard.
So, next time you are desperate for an RFI solution - use an AM radio to first figure out where your efforts should be concentrated!
You know the feeling: RFI and you really, really want to sort it out. After ages of getting nowhere, I started using a simple battery-powered AM radio to detect what was making noise.
This proved a very powerful system! Almost immediately, I could detect very strong RFI coming from a cheap HiPoint keyboard that I'd moved from my Raspberry Pi for use at the rig.
 |
| The HiPoint Model KBHM-660 keyboard (often sold with a mouse), which produces truly monumental RFI levels. |
The sheer level of RFI this small keyboard produced, despite having a metal base that might have made it well earthed, was incredible!
Replacing the keyboard with a standard curvy Microsoft unit instantly resolved the problem, and restored radio-quietness to the station! There is now no materially significant RFI from the recent changes to an external microphone and external screen and keyboard.
So, next time you are desperate for an RFI solution - use an AM radio to first figure out where your efforts should be concentrated!
Wednesday, 13 July 2016
RSGB Planning - A New Start?
Over the past weeks, John Mattocks, a retired Planning Inspector and still-active consultant, with very many years' experience, has taken over as Planning Advisory Committee Chair at the RSGB.
From a couple of initial contacts with John, he seems a very sensible, polite chap with a lot to offer.
More than this, John appears quite keen to make Planning a central issue in RSGB activities, rather than being relegated to a single, very outdated advice sheet and the odd support letter from the MD.
By the former MD, Graham Coomber's own admission, the RSGB has lapsed long ago into a kind of lazy resignation that it can't change planning in favour of hams. Consequently, it had, at least until John Mattocks took over, stopped even trying.
This is what John had to say this week in personal correspondence:
"It is certainly my intention that the RSGB, through PAC should, in future, take a much more pro-active role in seeking to influence Government thinking in terms of planning law and practice/guidance as it might affect radio amateurs. It is of particular concern to me that planners in England have lost the very useful parts of the former PPG8 dealing with issues such as radio interference and making specific reference to the hobby. The RSGB should have lobbied on the draft NPPF. We will have to be vigilant of any similar move in the other constituent parts of the UK although, I understand, there was never any reference in the Scottish guidance."
This is really very encouraging indeed, and I hope John is successful in carrying the other bigwhigs at the RSGB with him.
John adds:
"I intend to call the Planning Advisory Committee together for the first time in years at the Newark Hamfest at the end of September. The scope for taking a greater role in planning policy matters will be one of the items on the agenda."
That, too is very good news.
From a couple of initial contacts with John, he seems a very sensible, polite chap with a lot to offer.
More than this, John appears quite keen to make Planning a central issue in RSGB activities, rather than being relegated to a single, very outdated advice sheet and the odd support letter from the MD.
By the former MD, Graham Coomber's own admission, the RSGB has lapsed long ago into a kind of lazy resignation that it can't change planning in favour of hams. Consequently, it had, at least until John Mattocks took over, stopped even trying.
This is what John had to say this week in personal correspondence:
"It is certainly my intention that the RSGB, through PAC should, in future, take a much more pro-active role in seeking to influence Government thinking in terms of planning law and practice/guidance as it might affect radio amateurs. It is of particular concern to me that planners in England have lost the very useful parts of the former PPG8 dealing with issues such as radio interference and making specific reference to the hobby. The RSGB should have lobbied on the draft NPPF. We will have to be vigilant of any similar move in the other constituent parts of the UK although, I understand, there was never any reference in the Scottish guidance."
This is really very encouraging indeed, and I hope John is successful in carrying the other bigwhigs at the RSGB with him.
John adds:
"I intend to call the Planning Advisory Committee together for the first time in years at the Newark Hamfest at the end of September. The scope for taking a greater role in planning policy matters will be one of the items on the agenda."
That, too is very good news.
Wednesday, 6 July 2016
VE3OCL Balloon Tracked!
The latest in a series of small balloon flights equipped with HF transmitters is making its way across the Atlantic.
I first picked up VE3OCL, flight S-13, with its tiny 20mW output, at tea time yesterday (05/07/16), where it had already made very good progress.
This morning, just as I was about to give up listening, the balloon's signal appeared on the decode screen at a good -22dB. It's now out at almost exactly half way across the Atlantic.
Over the next 24 hours, wind flows will take the balloon rapidly from its current mid-latitudes position to a much more northerly one, possibly becoming trapped in a deep low making its way towards the UK from SW Iceland.
I first picked up VE3OCL, flight S-13, with its tiny 20mW output, at tea time yesterday (05/07/16), where it had already made very good progress.
 |
| Receiving VE3OCL balloon clearly this (06/07/16) morning. |
This morning, just as I was about to give up listening, the balloon's signal appeared on the decode screen at a good -22dB. It's now out at almost exactly half way across the Atlantic.
Over the next 24 hours, wind flows will take the balloon rapidly from its current mid-latitudes position to a much more northerly one, possibly becoming trapped in a deep low making its way towards the UK from SW Iceland.
LED Screen RFI - Or is it?
Yesterday, in my continuing attempt to clear the kitchen table of radio clutter, I took delivery of an LG LED monitor. This was to allow a notebook (remember those?) to be taken off the table and permit easier reading for tired, ageing eyes. The Samsung notebook and its PSU, now five years old, has never caused a whisper of RFI.
Whilst my station now looks a bit like those 'big guns' on QRZ, with their screens in the air looking like a NASA control room, the LED screen initially looked like a major regressive step and a total waste of £91.
The reason? RFI, of course!
Grounding the almost impossible to access chassis of the screen by using one of the VESA mounting screws to make the connection reduced the RFI by a small amount. But it wasn't possible to reduce it further. It was difficult to identify the exact source of the RFI, but it seemed initially that the switch-mode PSU might not be the culprit.
I opened up the switch mode PSU to see if any components had been left out. It seemed the PSU, whilst as basic as they come, was nevertheless reasonably filtered. I wrapped the mains and outlet cables around ferrite cores, but this didn't make any noticeable difference.
I read online that VGA cables, even when they have ferrites at both ends, can be powerful emitters of RFI when active. It was clear that, when there was no signal but the LED screen was nevertheless on (e.g. showing menu displays, etc.) , the RFI diminished drastically.
So, I took to wrapping my VGA cable in - wait for it - aluminium foil! I connected this to ground by means of an existing connection to the RF ground, keeping it in place with a simple cable tie.
Whilst this initially seemed to work spectacularly well, with no RFI resulting, that RFI soon came back.
The problem turns out to be related to the display resolution. If the native laptop resolution is used, the RFI is diminished. Or, rather, it shifts along in frequency such that the RFI might then occur outside of your current operating band. It doesn't disappear altogether.
The wrapping of the power line to the monitor, nearest to the screen itself, through a large ferrite collar several times made a drastic reduction in intensity of the RFI. But, again, it doesn't remove it altogether, and it can be strong on some frequencies.
I don't know why this problem occurs, so if you have more technical expertise or insight than me - and, let's face it, that isn't difficult - then please submit a reply to this post.
As a final precaution, I kept the monitor chassis grounded. I also soldered a small wire to the shield of the VGA cable and connected this to the station RF ground. I doubt it makes any difference at all, given the coaxial nature of the cable, and that the chassis ground should be taking care of the whole system.
After a few days, I decided, though, that this monitor produced far too much RFI for a situation where there was previously none. I switched the monitor for a 10-year old HP w22 monitor, which looks to be well shielded internally. Other than one or two very weak peaks on 12m, this monitor is RFI-quiet, and entirely acceptable. It also has a pleasing screen ratio, unlike today's letterbox screens!
So, out with the new, in with the old!
Update: Even the HP monitor produces too much RFI in a station where there is hardly any man-made noise. So, I'm back to the old laptop, which has no detectable interference issues.
Whilst my station now looks a bit like those 'big guns' on QRZ, with their screens in the air looking like a NASA control room, the LED screen initially looked like a major regressive step and a total waste of £91.
The reason? RFI, of course!
 |
| A clear table and easier viewing. But the RFI is bad...initially. |
Grounding the almost impossible to access chassis of the screen by using one of the VESA mounting screws to make the connection reduced the RFI by a small amount. But it wasn't possible to reduce it further. It was difficult to identify the exact source of the RFI, but it seemed initially that the switch-mode PSU might not be the culprit.
I opened up the switch mode PSU to see if any components had been left out. It seemed the PSU, whilst as basic as they come, was nevertheless reasonably filtered. I wrapped the mains and outlet cables around ferrite cores, but this didn't make any noticeable difference.
 |
| Just add foam! Whilst it doesn't fill me with confidence, this 19V, 2A SMPSU seems to be very well filtered. |
I read online that VGA cables, even when they have ferrites at both ends, can be powerful emitters of RFI when active. It was clear that, when there was no signal but the LED screen was nevertheless on (e.g. showing menu displays, etc.) , the RFI diminished drastically.
So, I took to wrapping my VGA cable in - wait for it - aluminium foil! I connected this to ground by means of an existing connection to the RF ground, keeping it in place with a simple cable tie.
Whilst this initially seemed to work spectacularly well, with no RFI resulting, that RFI soon came back.
The problem turns out to be related to the display resolution. If the native laptop resolution is used, the RFI is diminished. Or, rather, it shifts along in frequency such that the RFI might then occur outside of your current operating band. It doesn't disappear altogether.
The wrapping of the power line to the monitor, nearest to the screen itself, through a large ferrite collar several times made a drastic reduction in intensity of the RFI. But, again, it doesn't remove it altogether, and it can be strong on some frequencies.
I don't know why this problem occurs, so if you have more technical expertise or insight than me - and, let's face it, that isn't difficult - then please submit a reply to this post.
As a final precaution, I kept the monitor chassis grounded. I also soldered a small wire to the shield of the VGA cable and connected this to the station RF ground. I doubt it makes any difference at all, given the coaxial nature of the cable, and that the chassis ground should be taking care of the whole system.
After a few days, I decided, though, that this monitor produced far too much RFI for a situation where there was previously none. I switched the monitor for a 10-year old HP w22 monitor, which looks to be well shielded internally. Other than one or two very weak peaks on 12m, this monitor is RFI-quiet, and entirely acceptable. It also has a pleasing screen ratio, unlike today's letterbox screens!
So, out with the new, in with the old!
Update: Even the HP monitor produces too much RFI in a station where there is hardly any man-made noise. So, I'm back to the old laptop, which has no detectable interference issues.
Saturday, 2 July 2016
Kevlar Antenna Wire - Revised Perspective.
A couple of years ago, I wrote about the benefits of Kevlar-cored wire for antennas.
I concluded at the time that the relatively high price of Kevlar was worth it, principally due to it being three times lighter per unit length than Flexweave.
It won't be too long before I have to replace my 20m delta loop wire again. Despite the Kevlar core, the braid of tinned copper that is wrapped around it eventually suffers metal fatigue, and an open circuit develops.
Kevlar-cored wire's strength is in tension, not lateral flexing. Millions of movements over the years due to wind for a vertical delta made of this wire leads to the aforementioned metal fatigue. So, I find that Kevlar cored wire is best used in situations like dipoles, end-feds, verticals, and so on.
Having recently re-wired the house with DC from a solar installation, I came to thinking that, seeing as Flexweave may well actually outlast Kevlar-cored wire in that it is less prone to fatigue (as suggested by my 17m delta, which is made of Flexweave), I ought to use some of the DC wire (which is the same as medium speaker wire), which is also, of course PVC coated.
Sticking two identical lengths of Kevlar-cored and DC wire on a kitchen balance, I was surprised to find the DC wire was a full gram lighter than the Kevlar wire. If you multiply this up to the full wave length of a 20m vertical delta loop, that's a saving of 56 grams on the support. That's much the same weight as two AA batteries - quite significant. The width of both wires is the same, so there is no change in the wind-catching area.
There is also a big benefit to ditching Kevlar, because it's a pain to solder and add lengths to. You need to remove the Kevlar fibres, otherwise they absorb heat and contaminate the joint. This is important for repairs in windy winter weather. You are also compelled to use spade or similar connectors, because the copper braid of Kevlar-cored wire has no strength at all. With DC wire, soldering is simple, clean and strong.
Price-wise, Kevlar wire in its standard diameter is selling (mid-2016) for 90p per metre on a 100m drum. The DC wire is selling for 52p per metre, handily in 25m lengths (for a 14MHz antenna), almost half the price!
Once again, I'm happy to be saving you money, without any loss in electrical or mechanical performance.
I concluded at the time that the relatively high price of Kevlar was worth it, principally due to it being three times lighter per unit length than Flexweave.
It won't be too long before I have to replace my 20m delta loop wire again. Despite the Kevlar core, the braid of tinned copper that is wrapped around it eventually suffers metal fatigue, and an open circuit develops.
Kevlar-cored wire's strength is in tension, not lateral flexing. Millions of movements over the years due to wind for a vertical delta made of this wire leads to the aforementioned metal fatigue. So, I find that Kevlar cored wire is best used in situations like dipoles, end-feds, verticals, and so on.
Having recently re-wired the house with DC from a solar installation, I came to thinking that, seeing as Flexweave may well actually outlast Kevlar-cored wire in that it is less prone to fatigue (as suggested by my 17m delta, which is made of Flexweave), I ought to use some of the DC wire (which is the same as medium speaker wire), which is also, of course PVC coated.
Sticking two identical lengths of Kevlar-cored and DC wire on a kitchen balance, I was surprised to find the DC wire was a full gram lighter than the Kevlar wire. If you multiply this up to the full wave length of a 20m vertical delta loop, that's a saving of 56 grams on the support. That's much the same weight as two AA batteries - quite significant. The width of both wires is the same, so there is no change in the wind-catching area.
There is also a big benefit to ditching Kevlar, because it's a pain to solder and add lengths to. You need to remove the Kevlar fibres, otherwise they absorb heat and contaminate the joint. This is important for repairs in windy winter weather. You are also compelled to use spade or similar connectors, because the copper braid of Kevlar-cored wire has no strength at all. With DC wire, soldering is simple, clean and strong.
Price-wise, Kevlar wire in its standard diameter is selling (mid-2016) for 90p per metre on a 100m drum. The DC wire is selling for 52p per metre, handily in 25m lengths (for a 14MHz antenna), almost half the price!
Once again, I'm happy to be saving you money, without any loss in electrical or mechanical performance.
Friday, 1 July 2016
LED and EMC control - From ARRL.
Let's hope we see some better controls in the EU (and UK!)
------------------------------------------------------------
SB QST @ ARL $ARLB022 ARLB022 FCC's OET Clarifies Emissions Compliance Testing for RF LED Lighting Devices ZCZC AG22 QST de W1AW ARRL Bulletin 22 ARLB022 From ARRL Headquarters Newington CT June 30, 2016 To all radio amateurs SB QST ARL ARLB022 ARLB022 FCC's OET Clarifies Emissions Compliance Testing for RF LED Lighting Devices The FCC's Office of Engineering and Technology (OET) has clarified that all RF LED lighting devices falling under Part 15 rules as "unintentional radiators" must meet conducted and radiated emissions limits set forth in those rules. "Operation of Part 15 unintentional radiators is subject to the condition that no harmful interference is caused," the OET reminded, in a knowledge database paper released on June 17. "Manufacturers and users should therefore note that lighting devices are required to cease operation, if harmful interference occurs." The OET said radiated emissions measurements must be performed at least from 30 MHz to 1000 MHz to adequately demonstrate compliance with Part 15 (15.109). Its guidance, the OET continued, applies to RF LED lighting devices that, in the past, have been considered to operate on frequencies below 1.705 MHz. Previously, devices operating between 9 kHz and 1705 kHz had to be tested only for radiated emissions up to 30 MHz, where no specified radiated emissions limits exist, and were exempt from testing from 30 MHz to 1000 MHz. The OET said it recognizes that routine radiated emissions measurements are needed under Part 15, based on the highest frequency generated or used in the device. "[W]e have found that emissions from RF LED lighting devices are non-periodic, broadband in nature, and are produced as a byproduct of the internal driver circuitry within the RF LED lighting device," the OET "knowledge database" paper said. "These types of emissions have adequate energy and potential to generate radiated emissions well above 30 MHz." The ARRL Lab's Electromagnetic Compatibility Engineer Mike Gruber, W1MG, said he was pleased to see the FCC's OET clarify the test measurement requirements. He said ARRL is generally hearing more RFI complaints stemming from RF LED bulbs. "Not only are the emissions limits higher for Part 15 LED bulbs - as opposed to Part 18 fluorescent and CFL bulbs, they seem to be winning out in terms of consumer popularity," Gruber said. "Higher limits and more bulbs probably make for more complaints." Gruber said the Lab has seen LED lighting devices causing problems in the 2 meter band. "Since conducted emissions limits do not apply above 30 MHz, radiated emissions limits can be the first line of defense against RFI at these higher frequencies." Gruber pointed out that noise generated by street and traffic lighting can be widespread. In such instances, he suggested that Part 15b limits for residential areas should apply. "These limits are lower than Part 15a limits, which are intended only for commercial and industrial environments," he explained. "This is especially critical in cases where a pole transformer connected to the lighting device also feeds a home or residence. The 240 V split-phase secondary system can conduct RF into a residence through the service entrance panel." He suggested that the lower limits may benefit mobile users. The OET noted that the ANSI Accredited Standards Committee C63-EMC is drafting measurement procedures for lighting devices. "When complete, we expect it will address in greater detail the measurement procedures and configurations to be used in determining compliance," the OET said.
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