Killing Top Band Noise

Here in the “noisy neighbor suburbs” the name of the Top Band RX game is steering the nulls towards noise sources using the rotators, THEN using the NCC-2 to electrically steer the antennas toward the signal source! I use the P3 to “see” how I can break up the noise. The noise pattern becomes “dispersed” and as it breaks up, I hear more signal and less noise. Even 5 dB less noise means I can hear and work DX that otherwise would have been buried in the noise.

I play a little game when I leave work to see where the two loops ended up direction wise. For OA4TT, one was about 130 degrees, the other 180 degrees. They were “close enough” because their patterns – when phased with the NCC-2 – present a directional cardiod azimuthal beamwidth. Some days I am surprised at the directions, but because I live in a hilly area, it’s hard to know exactly how signals arrive at these antennas.

Listening to OA4TT again today (whom I worked yesterday on 160M for #94), I have been playing around with the rotators.

OA4TT’s signal is best just after his sunrise – at least yesterday and today

The name of the game is to steer the antennas so the nulls point at the noise sources, and at my QTH, the direction of the man made noise is different today than last night! This might mean that there is actually “noise propagation”. Think about it – the noise is pretty low frequency and is for sure ground wave. It can be caused by any neighbor up to some distance – I don’t know exactly what the drop off is, but from walking around with a portable AM radio, I have found that even rain gutters can pick up noise. Pardon the goofy rotator control box positions, but I am just waiting to work 3Y0Z and get that over with so I can tweak my shack (an ongoing process it seems). After 3Y0Z, I will:

  1. Take down the 17M EDZ and 20M two element yagi
  2. Put up the 30/40M Cushcraft D40 at 60′ with the 30M mod
  3. Replace the MFJ-1886 and MW550P with the new Wellbrook ALA1530LNP loop (my second one of these)
  4. Replace the SPE amp with the Elecraft KPA-500 and KAT-500
  5. Sell the AT2K , MFJ-1886 and MW550P

I will be a dyed in the wool 160 – 30M Low Bander. I would much rather have an antenna for 30 and 40M up 60′ than a 20M two element yagi up 40′ for the duration of the bottom of Cycle 24 – which I know we will start this year – probably in the second half of the year. All of the high bands will start becoming “anemic”. 160M has already started “turning” – the solar disturbances had their last hurrah last Fall, and 80M has been great lately, although its my least favorite band. 40M – as always – is the best band year round and solar cycle round.

We are going to eeek out the last drops of 15, 17 and 20M during 3Y0Z.

Im already looking forward to my post 3Y0Z plans, and their ship hasn’t even left yet – hi hi

Spring Has Sprung!

We have had a beautiful Winter here near San Francisco. Just enough rain and temperatures that hit 60 degrees F every day. It has been just perfect “antenna weather”.

The very first shrubs and trees are starting to bloom, and this will build for months.

We do need more snow in the Sierra’s though, so I’m hoping we reach a normal level. Last year was an extremely wet Winter.

How to Make the DX Engineering NCC-2 “Sing”

The NCC-2 has been an “elusive beast”. On Top Band, from a small suburban lot, the trickiest antenna effort I have ever had has been finding something that combats the man made noise and lets you hear very weak signal DX. I tried just about everything in the ON4UN Lowband DX Book, and have had what best could be described as a “meandering path”. Then one day, I accidentally had my DXE DV-40-P switched in on 160M – and Holy Moly Batman – it was like magic. That antenna became the one to beat.

I had some false starts. At one point the K9AY Loops were great. Then my neighbor did “something”, and they were swamped with noise – they became useless. I also tried several passive loops, and some had some success, but again, noise, noise noise.

Enter the Wellbrook ALA1530LNP. It has an amplifier that I seriously doubt ANY other loop can beat. But to make the NCC-2 sing, the best solution I have come up with is TWO Wellbrook ALA1530LNP Loops and the NCC-2.

Not only can I electrically steer the nulls, I can also physically rotate each antenna. Sometimes its for maximum gain, sometimes minimum noise, most of the time its both.

Here’s the funny thing – sometimes noise comes in from all kinds of weird directions here on my suburban lot. The rotators directions sometimes seems crazy, so I don’t care where they are pointed as much as I rotate until I get the best signal to noise ratio.

This is also why I like the loops way more than say two verticals. With verticals you can only electrically steer them. I can tell you from experience, when you also add in physical totation using cheapie rotators, then its like having 3D instead of 2D. Its a geometric imporvement for sure.

When testing the NCC-2 controls during the day, the most amazing test is at 1700 khz, where the Oakland International Airport is about 7 miles away as the crow flies, and where I can get the NCC-2 Phasing knob to select either the Oakland Airports 10 watt TSA station, or a high powered ESPN sports station in San Diego. To do this – one antenna is pointed South by Southwest and the other is actually more South by Southeast. Its the coolest thing. That test then leads to better DXing on 160M, like working OA4TT today. The S/N was quite a bit better than the DV-40-P, so I have hit a new milestone in my quest for the best RX antenna.

I would be surprised if I will ever beat this arrangement at this particular QTH. I just moved the rotators, and noise entered in. SO the physical rotation on top of electrical phasing in the NCC-2 just seems like something even better than anything else I can do.

Andy Ikin at Wellbrook is an expert in low noise high gain RX pre-amps, and the only way to make this better IMHO – is to follow Andy’s continual progress with his product development.

160M #94: OA4TT

That sure was easy. The phased loops through the NCC-2 ARE better than the DXE DV-40-P. It was easier to hear with this new set up. So I have stepped up my Top Band Receive – YAY!

What a great way to wake up. I still have these South American entities to go:

  • Chile
  • Guyana
  • French Guyana
  • The Falklands
  • San Felix
  • St. Peter and Paul rocks
  • Trinidad and Tobago
  • Juan Fernandez
  • Ducie
  • Fernando de Noronha
  • Trindade and Martim Vaz

In Central America, I still need:

  • Nicaragua
  • Panama
  • Guatemala

In the Caribbean:

  • St. Lucia
  • Dominica
  • St. Kitts and Nevis
  • Dominican Republic
  • Haiti
  • Navassa
  • Desecheo

Quite a few in OC-PAC and AS

So I have plenty of “easy” one’s to get to – so I will have fun on Top Band LONG after I reach Top of Honor Roll. Basically, 160M will be the only place I bother chasing DX seriously after Glorioso – and it won’t be for DXCC, it will just be to get my 160M total number higher.

That really sounds sweet to me because what I love about 160M the most is early morning coffee and DX. This has always been the “relaxing” side of DXing. No big deal if you don’t work them – but a nice little buzz if you do.

3Y0Z West Coast Watch: The Big Flip!

OK, today I very clearly saw what I couldn’t all week because I literally got home from work just after 20M closed. That was a theory, and my idea about the “Cross Quarter Days” does in fact make a big difference.

Right now, the days in the Northern Hemisphere are getting longer, and at an accelerating pace. 

What I noticed is that TODAY, 20M had a superb peak that lasted up to 2 hours before the “official” sunset for my latitude. Then there was an almost instantaneous switch over to 40M where it was even stronger than the 20M opening. I suspect 30M also was in that change over, but there were no stations to prove that out.

My next theory is that over the next two weeks, as the team is en route, we pick up 1/2 hour sunlight. And we then pick up another half hour while they are there 

This means I expect that the West Coast will enjoy a better pre sunset 20M opening.

I also stick with my idea that 40 and 30M will be the best bands for the West Coast.

“Emulating” a Wellbrook ALA1530LNP w/MFJ-1886 + MW550P

I just happen to have a Palstar MW550P Preamp Tuner for SWL and AM BCB DXing. I figure I would try it with the “anemic” MFJ-1886 loop.

The Wellbrook ALA1530LNP has TWO preamps – one at the antenna (P1) and one in the controller (P2).

I was able to “emulate” the Wellbrook using the MFJ-1886 and the Palstar MW550P. P1 is the MFJ-1886 antenna based preamp, and P2 is the MW550P Tuner / Preamp.

How does it play?

I brought the MFJ-1886 loop up to the same level as the Wellbrook. The great thing about this is that I can now see that the Wellbrook has less noise, but the “kludge” will be “good enough” until I receive my second Wellbrook loop in February. It is way more acceptable than having just the MFJ-1886 alone. With the P3 panadapter, I can clearly see that the MFJ-1886 plus MW550P is about 10 dB noisier, but that indeed it is at the same level – which is really important when you want to phase antennas using the NCC-2. So I do look forward to swapping the MFJ-1886 for the new Wellbrook.

Take Aways

  1. Don’t try to go cheap on your receive antennas. Buy the best, and I am sure the Wellbrook ALA1530LNP is one of if not THE best
  2. Use twp of the same antennas. This is even more important than I had expected

For me, the adventure in DX-ing and ham radio is learning along the way. I get just as much of a “buzz” thinking about solutions to problems and then trying them – both receive and transmit. Constantly striving to improve your station – or just trying new things can keep one interested for many years, if not a lifetime.

 

The Wellbrook ALA1530LNP Loop vs. The MFJ-1886 Loop

The hands down winner – the Wellbrook ALA1530LNP

I mentioned that I was very pleased with the MFJ-1886 loop – mainly because I was able to get an open box item at HRO Oakland, and none of it had been used. It was going to be a store display model, but they never went ahead and put it up. The store had several other loops on display – but they were all transmit loops.

Anyway, I had a chat with Andy Ikin at Wellbrook, and told him what I was going to do and it just turns out he did a technical evaluation of the MFJ-1886. Here is what he found:

Mechanically the antenna is very sturdy. Performance wise, it is disappointing when one compares to the established ALA1530. The MW gain is low i.e. 10-15dB below the ALA1530. Overall the HF gain is approx. 5dB lower. The MW IOP2 is approx. +50dBm and IOP3 is +28dBm

The poor IOP2 is mainly due to the absence of a balanced input transformer. The amplifier uses 2 x MIMICs in a pseudo balanced configuration i.e. it uses the output transformer to achieve a balanced input. Hence, by using  50 Ohm input z MIMICs in anti-phase gives an input z of approx. 200 Ohms.

The measured Input z over most of the design bandwidth is quite high at approx. 144 Ohms. Also the input has a 290 Ohm resistor to ground on each Amp. input. Hence, the input z is a combination of the 200 Ohm MIMICs loaded with two 290 Ohm resistors. The amp.  is only matched to the loop in the mid HF band. Normally a 500kHz to 30MHz wideband loop would have a nominal input z of approx. 15 Ohms. Therefore, there is a considerable loop/amp. mis-match at MF plus input attenuation in this frequency range.

Considering that MIMIC amps afford a high noise figure at MF plus an increase in NF due to the low z  loop shunting the amp. I would expect overall NF between 15 to 20dB . This is not going to bode well for NDB listerning.

The Amp. gain at 1MHz is 9dB increasing to a max. of 18dB at 10MHz. I have added 1dB to take into consideration 50 to 144 Ohm mismatch.

The low MW gain appears to compensate for the poor IMD performance.

On the air I haven’t been able to get past the fact that when I phase the Wellbrook ALA1530LNP against the MFJ-1886 that there is no contest. The MFJ loop seems to have half the output that the Wellbrook does, so after two days of testing, I’ve decided that the MFJ is what I said it is – an entry level loop that is well made and I would further that by saying its fine for general purpose HF SWL, but its NOT a great loop for 160M. You do get what you pay for – that’s for sure, and MFJ has a great “low cost option”. The problem is – on 160M, that’s not a great deal after all – the extra couple hundred dollars is much better invested in the Wellbrook Loop.

So – one way or another, I hope to have two Wellbrook loops phased and powered by the NCC-2.