A recent posting on the Yahoo ndblist Group page, by veteran LF/MW DXer and front-end guru, Steve Ratzlaff (AA7U) in Oregon, described his thoughts on LF/MW antennas and his experience with phasers:


Some years back at the other place, I experimented with phasers, trying
all the various ones I could find or build. I had a long term loan of
the DXE NCC phaser as well. I compared them mostly at MW where a phaser is generally most useful; but also at LF and HF. In all cases and all
frequencies, without exception, the Dallas Lankford "MW Phaser #2" was
significantly better. I have placed that article in the ndblist Files,
under "Aerials and Technical Files" section should you have an interest
in looking at that article.


For LF use I never found any reason to use a phaser for trying to
optimize the level of a signal. Usually LF signals are short-lived and
often you only have a short time to catch an ident before it fades away.
You can easily waste 30 seconds or more just trying to optimize the
phaser; by that time the signal is usually gone. For those with a local
noise problem from a single general direction a phaser could be useful
in nulling out that noise, though of course you would lose the signals
from that direction too.

I also had room for antenna experiments, being able to compare them with
my longwire antennas. For those with the room, I believe it's hard to
beat an elevated longwire of approx. 400 feet or longer. I was very
fortunate to be able to string two E/W 1600 foot longwires, on either
side of the property about 400 feet apart and roughly parallel; and a
much shorter 400 foot N/S longwire. But even the N/S short one enabled
me to log a number of Greenland beacons (of course this was back when LF
conditions were still excellent, not like now).

Some folks have good results with the K9AY type antenna--Doug in TX has
good results using that antenna. But it's a ground-dependent antenna and
many areas don't have ground characteristics that support such antennas.
My area was one of those--the K9AY never worked very well for me. But an
elevated vertical loop worked very well, using the Wellbrook ALA100
preamp. 

I had several rectangular loops up at one time, 120-150 foot
circumference using the ALA100, about 10 vertical feet distance between
the top and bottom wires to give a good capture area. These were very
sensitive at LF and a couple of times I was able to (barely) hear
distant South Pacific beacons that I was also hearing on the 1600 E/W
longwire. And of course the loop antenna is ground-independent so can be
used anywhere. It's bidirectional so can help in nulling noise too. And
such a loop doesn't take up much room as long as you can get it away
from local AC noise (which is true for all LF antennas, especially for
active whips).

Mark Connelly is a prominent east coast MW DXer and has a lot of info on
antennas and phasing on his webpage here.  All his applications are primarily for MW DXing but the principles apply equally
well to LF.

The Dallas Lankford phaser article described by Steve, can also be downloaded from here.

LNV phaser, John Bellini in Colorado, also chimed-in with some additional thoughts based upon his own experience:


Steve McDonald, VE7SL, is a regular contributor to AmateurRadio.com and writes from British Columbia, Canada. Contact him at [email protected].

A refurbishment of the shack is long overdue, and some advanced birthday money prompted me to take up one of ML&S recent deals. I had been looking at various Linear power supplies to feed the new layout, and the MP-304mkII would fit the requirement of servicing the array of rigs I have to feed.



Ordering was quick which I did over over the phone,  as normal with Martin Lynch & Sons, the faultless delivery was on time! Infact so quick! I had forgotten to tell the XYL, so she was surprised by the delivery.

The MP304 is sold as a 30A supply, that does 15A continuous, and 20A for 15minutes @13.8V. Supplied with a mains voltage of 230V 50Hz.

There are various output connections on the front, including a handy Cigar lighter socket that can supply 10A.

The supply is variable by an adjustable pot on the front panel, which is biased in the middle of its range to set the supply at the nominal 13.8V. The output is adjustable between 1.5V & 15V DC. With a sliding scale of V/I) (Don't expect 15A Max at 5V as this works out at about 7A)

The large easy to read analogue Meter is switchable either to Volts or Amps.  

Supply regulation is better than 1% and a noise figure <10mV is quoted.

We will see how this performs when I will load it up and do a few measurements in the next day or so.

A short form manual is supplied, a circuit diagram would of been useful for servicing in the future. (I have not seen one on the web?)

First looks are good, and not bad for the money of £99!



Steve, G1KQH, is a regular contributor to AmateurRadio.com and writes from England. Contact him at [email protected].

Well, I was delighted, honoured and surprised, to get a nice letter from the RSGB today. In it, it said I’d been awarded the Wortley-Talbot trophy for my experimental work on over the horizon work at 481THz and the article on this published in RadCom last year.

Sadly my continued ill health means I’ll be unable to pick up the award at the RSGB’s AGM in London in April.  I just wish my health was better so I could do some field work again soon! Both VLF and optical field work are on hold until I feel better. This year I really really hope I’ll manage it.

To be honest this award came as a complete surprise, but I’d happily trade these lovely awards to be back to my old healthy self.

Roger Lapthorn, G3XBM, is a regular contributor to AmateurRadio.com and writes from Cambridge, England.

Without much (if any) advertising the Google+ ‘Chinese Ham Radio Equipment‘ community reached a 1000 members today. I intentionally made the community public, so there’s no need for a Google account in order to read there.

The downside of a community becoming larger is spam. Some of it is captured by Google itself and kept in a moderation queue, but some of it slips through and has to be deleted by the moderators. Because the moderators live in different time zones, spam never lives long.

What I still miss a bit there is the interactive part. If the community would be just another URL with the same content, it’s basically pointless. Questions about Chinese ham radio? Ask there, there’s a lot of knowledge and experience there.

Also nice: a carton box.

The carton box didn’t waste much time to cover the distance between the USA and Europe, but took almost the same amount of time to travel from Amsterdam Schiphol airport to my QTH — a one hour drive under the most challenging traffic conditions. Customs took their time…

Hans, PD0AC, is a regular contributor to AmateurRadio.com and writes from Almere, The Netherlands. Contact him at [email protected].

We will be producing episode 76 of AmateurLogic This Friday night, March 6th at 7:00 CST, 0100 UTC.

You can watch us shoot it live at www.live.amateurlogic.tv, or download the edited version a couple of days later.

George Thomas, W5JDX, is co-host of AmateurLogic.TV, an original amateur radio video program hosted by George Thomas (W5JDX), Tommy Martin (N5ZNO), Peter Berrett (VK3PB), and Emile Diodene (KE5QKR). Contact him at [email protected].

First, I apologize for this cut-and-paste from QRZ.com. I won’t usually do that, but I spent a lot of time writing this, and I want to spread it around. They moderate, I’ve been “pre-approved” here on AR.com, so you’ll see it first. So I guess I “cut and pasted” from here to there. OK, I can live with that…

HamRadioNow Episode 193: DV is Exploding

David Rowe VK5DGR updates CODEC2 and FreeDV,
introduces a FreeDV “Speaker-Mic”, and is developing a
disruptive DV system for VHF/UHF

David Rowe VK5DGR is the ham who developed CODEC2*, and CODEC2 changes everything. So, is this a click-bait title, or a valid prediction?

In this program, David talks to me about the SM-1000 “speaker-mic”, a little box he’s developed to let hams use FreeDV digital voice without a computer. The box does all the processing and has all the input/output connections, so you can run digital voice over your SSB radio with no computer attached. The SM-1000 will be available soon for about $200.

We also talk about improvements to FreeDV and CODEC2 that David expects will make digital voice work as well as, and maybe a little better than SSB with weak signals or noisy HF conditions. Today, SSB can be copied below the level that a DV signal drops out, but it’s somewhat rough listening. Yesterday, you needed a lot more signal for DV. Tomorrow: parity with SSB, or maybe advantage: DV. Yes, there are plenty of issues left. Voice quality (many hams don’t like the ‘robotic’ sound or the fidelity). Contest/DX pileups. David readily admits that SSB has been around for so long on HF because it works great in that hostile environment. He sees it as a challenge.

Finally, David tells me about a VHF/UHF project he’s working that, at my first look, has the potential to disrupt everything in repeaters. It won’t happen overnight, and given ham’s investment in analog FM and even the newer DV modes from D-STAR to DMR and Fusion, it might not really happen at all. But here’s what David is aiming at:

• Signal to Noise that’s better than FM by 10 dB
• 5 kHz bandwidth
• TDMA “time-slice” modulation that will allow for “on-channel” repeaters.

By “on-channel” I mean repeaters that don’t need an “input” channel. As David described it, the repeater receives you for about 40 milliseconds, then retransmits what it just received. When you’re transmitting, your radio transmits for the 40 ms that the repeater is receiving, then stops while the repeater transmits. When you’re receiving, the software smooths it all out so it sounds like a continuous transmission. David didn’t say this, but I suppose it would allow you to monitor your signal thru the repeater in real time. This also means that a repeater works without a duplexer, and without some of the shielding needed to allow a high-power transmitter to operate right next to a sensitive receiver.

The disruptive part, though, is the 5 kHz bandwidth and no separate receive frequency. Cheaper, better repeaters that use far less spectrum will allow for dozens more repeaters to go unused everywhere. OK, that’s a snarky reference to the common complaint about unused repeaters in ham radio, but in commercial and public safety, where spectrum is in extreme demand, it really could change everything. And they have money.

David says that he needs to develop hardware for this because current hardware won’t handle the DV signal to make this work. His time-frame for a working prototype: end of this year. And his vision is a repeater that’s as simple as “an HT you stick up on the hill.” You might want something a bit more robust for your full-time repeater, but for fast emergency use… wow. On the other hand, I can see every DV mobile and HT having a “repeater” mode built-in. I see equal potential for utility and chaos on our VHF/UHF bands! Would we be up to the challenge?

Yes, DMR/MotoTRBO uses TDMA. They don’t use it for on-channel repeaters. They use it to allow two simultaneous conversations to occupy a single RF channel, but it still needs an input and an output frequency (and a duplexer), and occupies 12.5 kHz of RF bandwidth.

So, watch the show, and see the future…

*CODEC2 is the open-source software that digitizes speech into a very narrow, or slow, stream of data. The result: a highly useful, if a bit “robotic” sounding version of your voice that can be sent over a typical SSB transmitter, but using about half the RF bandwidth of typical SSB speech (2.5 kHz for SSB, 1.2 kHz for the DV). David’s been working on it for about 5 years, and he’s far from done. It works very well today. It’ll work even better tomorrow. Did I mention it’s open-source? Yes, there are proprietary codecs that do this. The AMBE codecs used by D-STAR, DMR and Fusion are the most common today. Is CODEC2 better? I’ll leave the technical arguments to those with the chops to make them. None of them are done. They’re all being improved. CODEC2 is free, and the hardware that uses it, typically SDR like FlexRadio, can be updated as new versions are released.

Links:

David’s Blog (details on FreeDV/CODEC2 development):
http://www.rowetel.com/blog/

Interview with David on “Linux in the Ham Shack”
http://lhspodcast.info/2015/01/lhs-episode-138-being-david-rowe/

David’s 2011 talk on CODEC2 at the ARRL/TAPR DCC:
http://youtu.be/bLb7stxOqmI

The 2011 DCC’s banquet talk – “The Village Telco” – David’s project to provide extremely low cost telephone service in East Timore, Africa.
http://youtu.be/1H1OVH1FwTQ

Gary Pearce, KN4AQ, is the host of HamRadioNow.tv. If you enjoy this and other HamRadioNow programs, help keep them 'on the air' with a contribution. Contact him at [email protected].

MW DXer, John Bellini in Colorado, has recently posted another interesting set of YouTube videos describing the mechanical construction and operation of his cool, and somewhat stealthy, Low Noise Vertical (LNV) as well as his phaser in action against some IBOC and local blowtorch signals.

  His use of the phaser is particulary interesting. Here he demonstrates what two LNV's can do when phased correctly. The second antenna being used is one of his wire LNV's located further back in the yard.

The first video shows phasing against local IBOC crud.



The second video shows the phaser in use to knock down the sideband hash from a strong local (KOA) signal, 25 miles away.


For those that like to DX in real time (unlike those using SDR overnight samplings), the phaser has much to offer.

The one being used in the videos is the Quantum Phaser and more information about it may be found here.

More on phasers next time.
Steve McDonald, VE7SL, is a regular contributor to AmateurRadio.com and writes from British Columbia, Canada. Contact him at [email protected].