AmateurRadio.com

New Turnstile Antenna / WWV - 25MHz

Last week's ARRL announcement regarding WWV's new circular polarized Turnstile antenna tests on their 25MHz transmitter quickly garnered my interest.




Their 25MHz signal used to be heard world-wide on F2 until it was dropped in 1977, but somewhat surprisingly, was resurrected in 2014.

I recall hearing its 2nd harmonic on sporadic-E very routinely on 50.000MHz when I first became active on 6m back in the late 60's. Back then it was also not uncommon to hear the 3rd and 4th harmonics of ship CW stations operating on 12 and 16MHz, at the very low end of 6m and just below the band edge on 49MHz.

6m Prop Indicator From The 70's!

They were often heard calling or working maritime land stations in Hawaii or Japan and the reception of these signals meant that the band was open out to the Pacific somewhere ... but of course there was no way of knowing just how far out they were and there were never any amateur signals to be heard.

Having not listened for WWV's 25MHz signal for several decades, I set up yesterday to see if it could be heard here in mid-summer. Using my Perseus SDR and my LF/MF inverted-L, self-resonant in the middle of the broadcast-band (gosh knows what the pattern looks like up on 25MHz!), I started monitoring just after lunch. I could detect their carrier which was very weak but steady, probably arriving on ionospheric scatter via the e-layer.

A few hours later I re-checked after hearing a few Colorado signals on 6m Es and sure enough, there they were with a fairly robust signal. It too, was no doubt arriving via sporadic-E as it was again today during another widespread Es opening from the PNW to as far south as Puerto Rico.

Here is a recording of the 25MHz signal made this morning with my Perseus SDR along with a comparison recording of their 20MHz signal, made about 30 seconds later.


There is not a lot of difference between the two and both run similar powers ... 2.5kW on 20MHz and 2kW on 25MHz. The 20MHz system uses a half-wave vertical on a 7.5m tower while the 25MHz outlet uses the crossed-dipole circular polarized Turnstile shown at the top of the blog.

Reception reports of their 25MHz signal are being sought and can be e-mailed to WWV at this address.

A posting yesterday in the Yahoo MW DXer's Group pointed to a new article at RadioWorld.com, re the new urgency within the broadcast field to address the growing noise floor.


The article "Noise Inquiry Spurs Recommendations" discusses the fallout from last year's FCC Technical Advisory Council's (TAC) Inquiry ET-16-191, seeking public comments on the rapid increase in "man-made RF noise issues".

As radio amateurs have known for decades already, there is a huge problem when it comes to spectrum noise levels. They were even complaining about this way back in 1932's Short Wave Craft ... "The reasons for this extraordinary amount of noise which we have to contend with at the present time are manifold." If only they knew how quiet it really was!

Now that noise is beginning to have severe affects on profit margins when it comes to AM, FM, TV and Wi-Fi connected devices, it seems that there may now be a larger appetite for some resolution.

"Other industries using RF wireless technologies report growing noise trouble as well. A recent IEEE Spectrum article was subtitled “Electronic Noise Is Drowning Out the Internet of Things.” Designers of IoT devices are not getting the range they expect due to unexpectedly high background noise, it reported."

Comments to the enquiry pointed out the usual offenders, all well-known to hams, such as noisy powerlines, switching power supplies, noisy motors etc and emphasized the fact that none of these offenders should cause interference if properly designed.

The TAC Working Group recommended some steps that it thought the FCC should take with the key one being an FCC Notice of Proposed Rulemaking to "resolve unanswered questions and take corrective action".

According to a recent meeting between The Association of Federal Communications Consulting Engineers and FCC officials, it was pointed out that:

• there had been no official RF noise studies done in over 40 years. 
• some manufacturers are deliberately cheating to skirt emission requirements.
• those in charge of enforcement (FCC) need to be more diligent. 

Much can be said for the same conditions here in Canada where our ISED has failed to properly safeguard spectrum noise pollution.
Other somewhat "telling" recommendations were also put forward and can be viewed in the Radioworld article here.

If you're one of the hundreds (thousands?) struggling with a new mystery noise source, perhaps you can identify the noise signature from one of these two sites:

http://www.arrl.org/sounds-of-rfi

http://www.rfiservices.com/sound.htm

It is reported that the new FCC Chairman seemed receptive to the concerns presented but so far there has been no official action. Hopefully he will soon tackle this with the same gusto shown for chasing down illegal broadcasters. With recent FCC cutbacks and proposed budget slashing from Washington, one wonders if this problem will be given the attention that it needs before it is truly too late to reverse.

A posting yesterday in the Yahoo MW DXer's Group pointed to a new article at RadioWorld.com, re the new urgency within the broadcast field to address the growing noise floor.


The article "Noise Inquiry Spurs Recommendations" discusses the fallout from last year's FCC Technical Advisory Council's (TAC) Inquiry ET-16-191, seeking public comments on the rapid increase in "man-made RF noise issues".

As radio amateurs have known for decades already, there is a huge problem when it comes to spectrum noise levels. They were even complaining about this way back in 1932's Short Wave Craft ... "The reasons for this extraordinary amount of noise which we have to contend with at the present time are manifold." If only they knew how quiet it really was!

Now that noise is beginning to have severe affects on profit margins when it comes to AM, FM, TV and Wi-Fi connected devices, it seems that there may now be a larger appetite for some resolution.

"Other industries using RF wireless technologies report growing noise trouble as well. A recent IEEE Spectrum article was subtitled “Electronic Noise Is Drowning Out the Internet of Things.” Designers of IoT devices are not getting the range they expect due to unexpectedly high background noise, it reported."

Comments to the enquiry pointed out the usual offenders, all well-known to hams, such as noisy powerlines, switching power supplies, noisy motors etc and emphasized the fact that none of these offenders should cause interference if properly designed.

The TAC Working Group recommended some steps that it thought the FCC should take with the key one being an FCC Notice of Proposed Rulemaking to "resolve unanswered questions and take corrective action".

According to a recent meeting between The Association of Federal Communications Consulting Engineers and FCC officials, it was pointed out that:

• there had been no official RF noise studies done in over 40 years. 
• some manufacturers are deliberately cheating to skirt emission requirements.
• those in charge of enforcement (FCC) need to be more diligent. 

Much can be said for the same conditions here in Canada where our ISED has failed to properly safeguard spectrum noise pollution.
Other somewhat "telling" recommendations were also put forward and can be viewed in the Radioworld article here.

If you're one of the hundreds (thousands?) struggling with a new mystery noise source, perhaps you can identify the noise signature from one of these two sites:

http://www.arrl.org/sounds-of-rfi

http://www.rfiservices.com/sound.htm

It is reported that the new FCC Chairman seemed receptive to the concerns presented but so far there has been no official action. Hopefully he will soon tackle this with the same gusto shown for chasing down illegal broadcasters. With recent FCC cutbacks and proposed budget slashing from Washington, one wonders if this problem will be given the attention that it needs before it is truly too late to reverse.

Last week's favorable northern declination of the Moon allowed me two days of activity, once my moonrises had lagged far enough behind the early sunrises.

With fixed elevation and not having the ability to track the moon as it rises, I can only operate for about two hours before the moon gets too high. The highest elevation that I am able to work seems to stop near 20 degrees.

With QSLs from earlier sessions still arriving, I noted last week's activity was down somewhat from the previous month ... summertime activities usually take priority over EME for most moonbouncers.








During my two mornings of moon time I worked five stations which included two new DXCC countries, bringing my 2m DXCC total to 30. Stations worked at the end of June were:

                    ON4AOI #106 (new country)
                    OH3AWW #107 (new country)
                    I2RV second QSO
                    DK9WI #108
                    IK6CAK #109

ON4AOI - 4 X 14V / 14H array

OH3AWW - 4 X 9el array

IK6CAK - 9H / 6V 8el LFA array more

Interestingly, all of the stations answered one of my CQs, with one CQ having three different callers at one time ... pretty exciting and something that I don't think has occurred here before! But that wasn't the only excitement of the week.

In the middle of a CQ following my QSO with IK6CAK, I heard a faint 'crack' sound from my amplifier, an aging RF Concepts 2-135, followed by the unmistakable whiff of a 'too hot' electronic component ... every ham is familiar with this always unwelcome odor and it usually spells trouble.



During the next CQ, I saw a trace of smoke coming out of the amp's back corner vent holes, at which point I reluctantly shut things down in the middle of some superb EME conditions.

After tearing into the amplifier, the only thing that looked stressed was a small inductor (L14 below), part of the output filtering / impedance matching circuitry.


It looked a little darker and somewhat stressed and as I gave it a poke with a screwdriver blade, it immediately disintegrated into what you see below.


It was a small (1.2uH) encapsulated RFC which appeared to be wire-wound on a core material that I did not recognize and likely suitable for VHF. I surmised that after several years of 100% duty-cycle JT65 operation, the inductor had been over-stressed to the point of failure ... helping to filter all of those nasty high frequency harmonics can't be an easy job!

After a search of my RFC collection (see below), salvaged mostly from junked TVs, monitors, VCRs and other electronic cast-offs temporarily 'borrowed' for stripping from our local recycle center here on Mayne Island, I settled on a 1.2uH choke that I hoped would be a suitable replacement. It had just a few turns so I assumed it was wound on some sort of powdered iron or ferrite form. Whether or not it would behave at 144MHz was another question.


After reassembling the amplifier the following morning, I keyed up at full power during the EME window but halfway through my initial CQ I saw smoke and then flames coming from the inside of the case ... yikes! Shutting down immediately killed the fire and after tearing into the amp yet again, I saw that this time, the output coupling capacitor (C51) had completely destroyed itself.


The new inductor (L14) appeared a little heated, but I assumed it was only smoke-damaged from the nearby flameout of the capacitor. I replaced C51, an 820pF silver mica, with a higher rated one of the same value and, once again, gave it the smoke test ... literally.

After a few seconds, a whiff of smoke appeared from the back of the amp, followed by the SWR trip-out kicking in and shutting the amp down.

This time it appeared that the inductor was definitely complicit in the destruction of the capacitor as it was charred and black. I surmised that whatever core material the little inductor was wound upon, definitely was not suitable at 144MHz and had caused the little inductor to either change value or to saturate ... whatever it was doing had created a highly reactive condition in the output circuit, changing the output load impedance and sending the SWR sky-high.

This time I replaced the inductor with a homebrew one, wound on a plain phenolic former, hoping to avoid any ferro-magnetic / frequency compatibility issues. After reassembling the amplifier, it seemed to be happy once again and ran nicely for several 60 second JT65B sequences at full power with no smoke or component heating!

By this time I had run out of favorable EME windows as my moonrises were now too far to the south to keep me away from the neighbour's trees ... I'll just have to be patient and wait until the end of the month for the next definitive test. Let's hope there's no more smoke.

Last week's favorable northern declination of the Moon allowed me two days of activity, once my moonrises had lagged far enough behind the early sunrises.

With fixed elevation and not having the ability to track the moon as it rises, I can only operate for about two hours before the moon gets too high. The highest elevation that I am able to work seems to stop near 20 degrees.

With QSLs from earlier sessions still arriving, I noted last week's activity was down somewhat from the previous month ... summertime activities usually take priority over EME for most moonbouncers.








During my two mornings of moon time I worked five stations which included two new DXCC countries, bringing my 2m DXCC total to 30. Stations worked at the end of June were:

                    ON4AOI #106 (new country)
                    OH3AWW #107 (new country)
                    I2RV second QSO
                    DK9WI #108
                    IK6CAK #109

ON4AOI - 4 X 14V / 14H array

OH3AWW - 4 X 9el array

IK6CAK - 9H / 6V 8el LFA array more

Interestingly, all of the stations answered one of my CQs, with one CQ having three different callers at one time ... pretty exciting and something that I don't think has occurred here before! But that wasn't the only excitement of the week.

In the middle of a CQ following my QSO with IK6CAK, I heard a faint 'crack' sound from my amplifier, an aging RF Concepts 2-135, followed by the unmistakable whiff of a 'too hot' electronic component ... every ham is familiar with this always unwelcome odor and it usually spells trouble.



During the next CQ, I saw a trace of smoke coming out of the amp's back corner vent holes, at which point I reluctantly shut things down in the middle of some superb EME conditions.

After tearing into the amplifier, the only thing that looked stressed was a small inductor (L14 below), part of the output filtering / impedance matching circuitry.


It looked a little darker and somewhat stressed and as I gave it a poke with a screwdriver blade, it immediately disintegrated into what you see below.


It was a small (1.2uH) encapsulated RFC which appeared to be wire-wound on a core material that I did not recognize and likely suitable for VHF. I surmised that after several years of 100% duty-cycle JT65 operation, the inductor had been over-stressed to the point of failure ... helping to filter all of those nasty high frequency harmonics can't be an easy job!

After a search of my RFC collection (see below), salvaged mostly from junked TVs, monitors, VCRs and other electronic cast-offs temporarily 'borrowed' for stripping from our local recycle center here on Mayne Island, I settled on a 1.2uH choke that I hoped would be a suitable replacement. It had just a few turns so I assumed it was wound on some sort of powdered iron or ferrite form. Whether or not it would behave at 144MHz was another question.


After reassembling the amplifier the following morning, I keyed up at full power during the EME window but halfway through my initial CQ I saw smoke and then flames coming from the inside of the case ... yikes! Shutting down immediately killed the fire and after tearing into the amp yet again, I saw that this time, the output coupling capacitor (C51) had completely destroyed itself.


The new inductor (L14) appeared a little heated, but I assumed it was only smoke-damaged from the nearby flameout of the capacitor. I replaced C51, an 820pF silver mica, with a higher rated one of the same value and, once again, gave it the smoke test ... literally.

After a few seconds, a whiff of smoke appeared from the back of the amp, followed by the SWR trip-out kicking in and shutting the amp down.

This time it appeared that the inductor was definitely complicit in the destruction of the capacitor as it was charred and black. I surmised that whatever core material the little inductor was wound upon, definitely was not suitable at 144MHz and had caused the little inductor to either change value or to saturate ... whatever it was doing had created a highly reactive condition in the output circuit, changing the output load impedance and sending the SWR sky-high.

This time I replaced the inductor with a homebrew one, wound on a plain phenolic former, hoping to avoid any ferro-magnetic / frequency compatibility issues. After reassembling the amplifier, it seemed to be happy once again and ran nicely for several 60 second JT65B sequences at full power with no smoke or component heating!

By this time I had run out of favorable EME windows as my moonrises were now too far to the south to keep me away from the neighbour's trees ... I'll just have to be patient and wait until the end of the month for the next definitive test. Let's hope there's no more smoke.