Category Archives: Antennas

Tony’s homebrew mag loop antenna and amplifier

Fullscreen capture 10312015 115110 AM

Yesterday, Tony (K3DY), shared a video (via Twitter) demonstrating his new home brew loop antenna and amplifier.

This is actually a great demonstration of how even a relatively simple, inexpensive loop antenna can improve reception in locations with heavy radio interference. Tony includes the following notes with his video:

“Testing a new receiving loop antenna that I built today. It uses a pre amplifier based on deferential setup of two 2N5109 transistors. Loop is made out of coaxial cable, only the shield is connected to the circuit.

Quick demo on 31 meters, lots of stations at sunset time. No time for further testing but I observed a pronounced directivity below 7 MHz. 75 meters is so quiet that it makes me forget I live in a townhouse. As a comparison, my noise level on 75 meters is at S8 on an end fed [antenna].

https://www.youtube.com/watch?v=bq_gKNQSVeA

I will use this loop primarily for SWLing purposes but I may use it as a separate receiving antenna with my amateur radio equipment.

A lot of fun, loops are fascinating and efficient!

Indeed, Tony! And perhaps the icing on the cake is that loop antennas are so portable, low-profile and easy to deploy. They’re ideal for those living in restricted areas and with picky home owners’ associations.

Inspired by my buddy Vlado (N3CZ), I’ve actually been collecting the pieces to build my own mag loop antenna this winter. I doubt the parts for my loop will exceed ten dollars as I plan to use the shield of some heavy coax for the primary loop and a little PVC for support (much like Tony’s loop).

Tony’s video is inspiring me to go a step further and also build a simple amplifier. Any suggestions or schematics for doing so are most welcome!

Spread the radio love

Bill’s simple Sony SRF-59 passive loop antenna modification

Sony-SRF-59-AM-Loop-Antenna

In reference to our previous posts about the Sony SRF-59 ultralight receiver, SWLing Post reader, Bill Mead, writes:

“As someone who doesn’t normally open the backs of radios, this is my mod on my ultralight. All it takes is a bit of electrical tape to hold the belt clip on the loop.”

That is, indeed, a brilliant and simple mod. The SRF-59 inductively couples to the loop antenna, so no soldering is needed; simply tape the belt clip to the loop, making sure the position is convenient for tuning the SRF-59 and the loop’s capacitor.

You can find passive loop antennas ranging from $19 to $50 US. The Grundig AN-200 and the Terk AM Advantage are two models currently on the market. Here are a few places you can check prices:

Grundig AN-200:

Terk AM Advantage:

Spread the radio love

TASS: An Arduino-based antenna switch

TASS

Many thanks to SWLing Post reader, Stan (WA1LOU), who writes:

“Enjoy your blog. I have been reading it for years. [H]ere is something your readers might be interested in that I mentioned in my blog today:

http://www.horzepa.com/2015/09/computer-controlled-switch-system.html

Very cool! Goes to show that there are a countless number of applications for the Arduino system to be used with amateur and shortwave radio.

Click here to read Stan’s informative post, and here to order the TASS system from TAPR.

John Ackermann also produced this informative presentation/video about the system:

https://youtu.be/P-TUM2dOi4c

Spread the radio love

Ken’s low-profile, low-cost vertical antenna

Vertical1

Ken’s antenna “deployed” in his back yard.

SWLing Post reader, Ken Hansen (N2VIP), writes:

A few months ago I purchased a couple S9V18 18′ vertical antennas for $65 at cheapham.com, with the intention of deploying a quick HF aerial at my HOA-laden home for ham radio use. I found they work great for SWL.

The S9V18 antenna is made to slip over a 1″ o.d. pipe driven into the ground at least a foot, with 12″ of the pipe rising off the ground. You can pound a two foot pipe half-way into the ground, or do as I did and fill a bucket with cement and stick the pipe in that half-way.

This is a 'close-up' of the bucket. Note the plate the ground radials are attached to, it's from Home Depot, it's a bus bar designed to bond the ground wire for each circuit in a breaker box.

This is a ‘close-up’ of the bucket. Note the plate the ground radials are attached to–it’s from Home Depot, it’s a bus bar designed to bond the ground wire for each circuit in a breaker box.

After adding a reasonable ground plane of 8x 14 ga wire cut about 15′ long I hooked up a 4:1 balun and ran it to my Kenwood TS-570D.

What I found was the aerial not only worked well on 20 meters, it also made a great shortwave aerial! Stations were booming in here in Texas at night.

Vertical4

The antenna slides over the pipe sticking out of the concrete in the bucket. Here is a picture of the bucket before the antenna base is slipped over it.

My ‘discovery’ was that a nice, modest vertical antenna can really improve reception on SW bands…

Cheapham.com sells the S9V18 antenna on close out for $35/each, the 2′ pipe is a few dollars more, add in a bit of coax and a modest ground plane and you can really up your SWL ‘game’.

Antenna on closeout:

http://www.cheapham.com/s9-v18-18-vertical-antenna-closeout/

I suggest anyone buying this antenna seriously consider buying additional clamps at the same time, they are just a few dollars and will help extend the life of the antenna:

http://www.cheapham.com/products/S9V18-Replacement-Clamps.html

For shortwave broadcast listening a direct connection without balun would probably suffice, but I used an LDG 4:1 balun to support multi-band ham transmitting:

http://www.cheapham.com/rba-4-1-voltage-balun/

Just thought I’d share my ‘discovery’…

And we thank you for sharing your discovery, Ken! This is a great, simple solution for those who cannot erect a permanent “high-profile” antenna. I’m especially impressed with how budget-friendly your solution is, Ken.

Post Readers: If you have other suggestions for inexpensive low-profile antennas, please contact me or comment below!

Spread the radio love

Portable antennas: a review of the Par Electronics EF-SWL

Last August and part of September, I traveled through the US with the CommRadio CR-1 and a couple of portable antennas: the Par Electronics EF-SWL and  NASA PA-30. I had the opportunity to try both in the field, and took notes as I used them. Following is a short review of the Par Electronics EF-SWL.

The EF-SWL ready to deploy.

The EF-SWL ready to deploy with my Spec.-Ops. Brand “All Purpose Bag.”

Par Electronics EF-SWL 

At the Dayton Hamvention last year, I had the pleasure of speaking with representatives of the North Carolina-based LNR Precision Inc. LNR is a mom-and-pop company with a focus on providing antennas, keys, and transceivers for the ham radio and shortwave listener markets.  Indeed I have several SWL friends who use on a daily basis an antenna this company manufactures and retails: the Par Electronics EF-SWL. LNR asked if I would consider reviewing their antenna, and since I was planning a road trip with radios in tow–the perfect opportunity to test such an antenna–I agreed.

The Par Electronics EF-SWL is an end-fed shortwave antenna designed for 1-30 MHz reception. It’s a receive only-antenna–perfect for the SWL. The radiator is 45 feet of #14 black polyethylene coated Flex-Weave wire. When I first used the EF-SWL, I noted the quality of its construction: no doubt it can withstand many deployments in all weather conditions–and it’s manufactured here in the US.

With a 45′ radiator, the EF-SWL needs a little space, but offers more gain than the other portable antenna I packed, the NASA PA-30 (look for its review in the near future). I put the EF-SWL to use in New Mexico where several large trees were readily available. I hooked the EF-SWL up to the CommRadio CR-1 and simply hung the end of the radiator as high as I could in a nearby tree. Though not a picture-perfect installation, it nonetheless certainly did the trick! I didn’t bother with a ground connection as I wasn’t in an area with much radio noise (RFI).

In the past, when setting up portable ham radio and shortwave listening, I’ve typically built my own antenna either for the specific meter band I hoped to use, or brought along a portable antenna tuner. It was quite nice having an antenna designed to be resonant on the broadcast bands.

Par-EF-SWL

Though I didn’t do this, I did noticed that the EF-SWL’s radiator is attached via a stainless stud–Par Electronics did this so you can remove the radiator and replace it with a different wire length. With the stock 45′ radiator, I still find the EF-SWL quite portable, especially when compared with most of the portable amateur radio antennas I use, which tend to take a dipole or delta loop configuration.

After returning from my trip, I decided to hook up the EF-SWL at my home base for longer-term evaluation. These past months I’ve had it on the air as an auxiliary antenna, and I’ve been impressed with its performance. In truth, it’s not in an optimal location hanging off the corner of my house, but I think this may actually represent with some accuracy the installation most SWLs will likewise be able to provide–in other words, placement that must factor in antenna restrictions or limited space. Of course, for any permanent installation, you will need to ground the EF-SWL for lower noise reception.

And yet, even in these suboptimal conditions, the antenna performs remarkably well.

As with any exterior antenna, of course, take precautions against lightening if you live in an area with thunder storms. If nothing else, at least disconnect the antenna when not in use.

Moving forward, I will plan to relocate the EF-SWL to a more ideal permanent location and most likely purchase another to keep in my antenna bag. I hope to use this antenna in a DXpedition I’ve planned later this year.

The EF-SWL retails for $75 US directly from LNR Pecision or $72 US from Universal Radio.

Note that LNR also sells a number of QRP field-portable transceivers: the LD-5, FX-4a and Mountain TopperClick here for more details.

Spread the radio love

Bonito adds new products

The Bonito MegaLoop ML200

The Bonito MegaLoop ML200

I’ve just heard from German manufacturer, Bonito, who has added several new products to their product line:

MegaLoop ML200: The MegaLoop is a 5 meter active stainless steel loop antenna that can be used outdoors. The MegaLoop ML200 ships with a Dual Power power supply (including the ability to power via USB).

Bonito notes that the Megaloop ML200 is currently available for a special price of 279,00€ (incl. 19% VAT)  at HamradioShop.net.

megactiv-83

The MegActiv 305

MegActiv 305: The MegActiv 305 is a compact antenna designed for low-noise reception between 9 kHz and 300 MHz. It has a radiating element of 18cm and can be powered with 5-15 VDC (max.120mA) or with the supplied Dual Power unit CPI 1000DP via USB.

The MegActiv 305 will be available for purchase end of April for an introductory offer of 174,99€ (incl. 19% VAT).

Fenu at fenu-radio.ch will review a sample of the MegActiv 305 in the near future.

OVP1000 Over Voltage Protector: The OVP1000 is an in-line over voltage protector for your receiver. It’s designed to dissipate current pulses caused by nearby thunderstorms. The OVP 1000 protects against high power surges in three ways:

The OVP1000

The OVP1000

  • A gas discharge tube with 60V firing voltage, max. pulse leakage current 1kA (8/20µs)
  • An ultra-fast ESD diode (30KV; max. pulse power 350W (8/20µs)
  • Blocking DC voltages (up to max. 100V) at the input and output.

The OVP1000 is available now for 59,00€ at Hamradioshop.net.

For full details about these new products, please visit Bonito’s blog.

And many thanks to Bonito who is a proud sponsor of the SWLing Post!

Spread the radio love

Eton Traveler III/AN200 bundle at Universal Radio

The Eton Traveler III

The Eton Traveler III

This morning, I noticed that Universal Radio is now bundling that AN200 medium wave loop with the purchase of a Eton Traveler III.

TecsunAN200I’ve had an AN200 for years and it does make quite a different when inductively coupled with portable radios. You simply set the AN200 next to your portable radio, tune your radio to a station, then adjust the AN200 tuning knob for maximum gain. It’s pretty impressive, especially when used with radios hat lack a good ferrite bar antenna.

Gary DeBock gave the Eton Traveler III high marks for medium wave reception (less for shortwave, though) in his recent Ultralight Shootout.

Click here to view this deal on Universal Radio’s website.

Spread the radio love