Category Archives: Accessories

HRO consignment deal: HEROS technology VLF-LF up-converter

Many thanks to SWLing Post contributor, Ron, who is a fan of longwave DX and notes that HRO has a Heros Technology VLF/LF up-converter on consignment/used. Ron mentions that the $140 price tag is quite a bargain for customers in the US market. Ron notes::

Here is a Link to the User Manual with pix of inside and some very cool videos of it in action:
https://www.herostechnology.co.uk/pages/VLF_LF_Converter.html

https://vimeo.com/119645116

And here is a Link to the one at Ham Radio Outlet:
http://www.hamradio.com/detail.cfm?pid=91-004203

New ones are $235 delivered to your door from London-no U.S. source.

Thanks, Ron!

Click here to view at HRO.

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The W6LVP magnetic loop antenna

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Many thanks to SWLing Post contributor, Troy Riedel, who asks:

Just curious if you or anyone you know have any experience with Magnetic Loops from W6LVP? […]Here’s his eBay page – 458 feedbacks and 100%.

Thank, Troy! I’ve never used the W6LVP loop, but the price–in comparison with other wideband mag loop receive antennas–is very attractive.

W6LVP currently offers two models of loop antennas:

Here’s the product description of the Mag Loop with Power Inserter from the W6LVP website (where orders can also be made–pricing identical to eBay):

The Wellbrook Model ALA1530LN-2 and DX Engineering (Pixel/Inlogis) Model RF PRO-1B magnetic loops are both good amplified receive antennas. However, they are both expensive. Shipping the Wellbrook antenna from the UK to the US adds another $100.

Extensive side-by-side testing of the Wellbrook, DX Engineering, and W6LVP receive loops was compiled using simultaneous WSPR signal-to-noise reception reports on all LF, MF, and HF amateur bands. In addition, extensive laboratory bench tests measuring gain, signal-to-noise ratio, and IMD were also performed. Signal-to-noise ratio is important to pull weak signals out of the noise and IMD is important to reject distortion caused by nearby strong transmitters such as AM broadcast stations. In both test regimens, all three antennas performed very well and without significant difference.

The antenna version listed here includes a power inserter for use with receivers or with transceivers that have a separate receive antenna input. If your rig doesn’t have a receive antenna input, check out my antenna with a transmit/receive switch.

If you live in the shadow of one or more high-power AM broadcast transmitters, contact me about a special version just for you. Please contact me at [email protected].

W6LVP amplified receive-only magnetic loop antenna (boy is that mouthful):

The W6LVP mag loop is a complete receive antenna system delivering top-of-the-line performance to amateur radio operators and SWLs – particularly for those with space and/or budget limitations. It is a great complement to vertical or wire transmit antennas. You have a knob to turn up the power but don’t have one to turn up the received S/N.

Ten foot circumference (approximately 1 meter diameter) loop. Small size yields a natural stealth for HOA challenges. The loop is rigid enough to maintain its shape but flexible for portable transport or attic installation.

Includes a low-noise, broadband amplifier covering 2200 (135 kHz) through 10 meters (30 MHz) with no tuning or adjustment. Perfect match for continuous tuning SDR receivers. Great for contesters to quickly check all bands. Greater coverage is possible at reduced performance.

Light-weight antenna structure fabricated from furniture-grade PVC yields a strong but very light antenna weighing only 2 pounds (not including power inserter or power adapter). Great for both portable/camping as well as fixed installations. Light weight and small size make for lower shipping cost – particularly compared to shipping from the UK.

Directly compatible with a low-cost speaker tripod stand (not included) for portable operation.

Compatible with light-duty rotator (recommended) for fixed operation. Loop can be rotated to null interference by up to 30 dB or enhance desired signals.

Includes low-noise linear AC power adapter to generate clean 12 volts for the loop amplifier. Unlike the DX Engineering antenna which requires 24 VAC, power can be easily supplied by 12 volt batteries during portable operation. Reverse polarity and short circuit protection provided by automatically resettable fuse.

Eham reviews are very positive–so far, 5 stars on all six reviews.

I also discovered this short video of W9OY comparing the W6LVP loop to a full size 80 meter vertical (verticals are much more susceptible to noise than loops):

Click here to view on YouTube.

I am very curious if any SWLing Post readers have ever compared the W6LVP loop to the Wellbrook or Pixel Loop antennas.

I actually own the Pixel Loop and might very well purchase, review and compare the W6LVP loop later this year (if time allows).

If you own the W6LVP loop and/or have compared it with the Pixel or Wellbrook, please comment!

Click here to view W6LVP antennas on eBay.

Click here to view the W6LVP website.

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New RX7300 adds receive-only antenna port to Icom IC-7300

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(Source: Southgate ARC)

New receive antenna socket for IC 7300

IHSG and Vibroplex/INRAD announce the release of a new accessory product for the Icom IC-7300 which provides a receive antenna socket on the rear of the radio.

The INRAD model RX7300 allows the user to add a receive-only antenna jack to the Icom IC-7300. This easy to install plug-in modification requires no soldering and is simple to install and easily reversible. The RX7300 can also be used for the insertion of accessory items into the receiver chain on the IC-7300 like receive-only bandpass filters, low noise preamps, etc.

When installed, the transceiver will use the SO-239 antenna connector on transmit, and one RCA phono jack on the RX7300 for receive. To use the transceiver in normal operation via the SO239, leave the RG-174 coax loop installed between the 2 phono sockets.

The RX7300 retails for £49.95 or £99.95 fitted and is only available through HIS group affiliated stores. Customers who purchased their IC-7300s via an IHSG store will receive a £5.00 discount from the supply only price and £15.00 discount from the installed price.

For more information contact [email protected]

www.nevadaradio.co.uk
www.hamradiostore.co.uk
www.inrad.net

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FM Notch Filter for SDRPlay RSP1

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RF filters are used (as the name implies) to filter/remove the frequencies you are not interested in and/or let frequencies you want pass . They come in lots of types. For example a band-pass filter lets the signals in a frequency range to pass through it and rejects/attenuates other frequencies. The opposite of band-pass filter is a band-reject or band-stop filter (also called a notch filter) which rejects/attenuates signals in a specific range and lets other frequencies get through the filter. Lots of different filters are used in SDRs and traditional radios. For example AM low-pass filters (only let frequencies lower than 1.7MHZ or so pass) or band-pass filters for various ham radio bands.

One of the popular use cases for a notch filter is in the FM broadcast range (88-108 MHZ in most parts of the world)

When you live near a powerful transmitter, it can affect the operation of your receiver in other near frequencies (or overload your receiver’s front-end), but I didn’t want the notch filter for this reason. I’ve got a SDRPlay RSP1 (among many other SDRs) which due to its architecture, has some images of FM band in the UHF range (for example in 330-350 MHZ). In fact they’re the images of the product of LO harmonics and FM frequencies.

You can temporarily move/shift the frequency by changing the LO frequency which does not remove them, but moves them around.

Another method to remove these images is using a band-stop filter.

This is the filter I’m using (Thanks to my friend Amirhosein Hasanpur who designed and built it):

Here you can see the effect of using a FM notch filter on my SDRPlay RSP1:

FM, without filter:

FM, with filter:

UHF (images) without filter:

UHF (images) with filter:

Here’s a link to a Zip file containing the PCB (in Protel), schematics (pdf) and S Parameters (pdf):

https://www.dropbox.com/s/l98kylrofohgqxf/SWLing.zip?dl=0

Note: Like any other SDR test/review, the results depend on lots of different parameters (various gain values, LNA, antenna, software, etc). These pictures are captured with the same conditions just to show the effectiveness of this filter and your milage will definitely vary, but expect a similar outcome. If you live close to a powerful transmitter or use LNAs, you will receive some signals, even when using the filter.

Final note: this issue is solved in the newer version of SDRPlay (RSP2) : it has software-selectable notch filters for FM and MW broadcast frequencies.

Mehdi Asgari, the author of this post, is a regular contributor to the SWLing Post. Mehdi lives in Tehran and is an active member of the EP2C amateur radio club.

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Panasonic RF-2200: Mario spots the model RD-9820 matching coupler

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Many thanks to SWLing Post contributor, Mario Filippi (N2HUN), who writes:

This antenna coupler was the companion for the RF-2200, they come up once in a while on eBay. Just some radio memorabilia/trivia to store away in the SWL file of brain hihi.

Click here to view on eBay.

Thank you, Mario! Until last year or so, I wasn’t aware the RF-220 had a matching coupler. I’m sure radio collectors would jump on one of these in good condition. It’s a lot to pay for a simple coupler, though this seller appears to accept best offers.

The great thing about eBay is if you’re looking for something rare and are willing to pay for it, the world is your oyster.

On the other hand, there’s exactly what Mario implies: many of us find eBay to be an amazing resource for discovering rare radio items, tucking them away in the dark recesses of our radio brains, which then helps us spot them when they pop up at local hamfests, swap meets, yard sales or thrift stores!

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Southgate ARC: What Is a Balun and How to Make One Cheaply

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(Source: Southgate ARC)

Ham Radio – What Is a Balun and How to Make One Cheaply

A Balun is a transformer which allows coaxial cable, which is an unbalanced lead to be connected to a balanced load, for example a resonant aerial.

The 1:1 balun is often called a choke balun, it works by eliminating Radio Frequency currents flowing on the outside of your coaxial cable, this is important because it prevents the pattern of the dipole becoming distorted and prevents the braid of the coaxial cable radiating.

Connecting coax to your resonant dipole which can be configured in a V shape or in a sloping fashion, however serious power loss and feeder radiation can occur without the use of a balun transformer. No one wants to induce Radio Frequency currents into Television receivers or Broadcast equipment as it may result in disputes with neighbours and could possibly lead to your station having to close down. Try to keep the centre of your aerial away from buildings as it may induce Radio currents into the mains wiring.

Building a choke is not difficult all you need is some plastic pipe available from many Do It Yourself outlets and warehouses. I use a length of about 1 foot of plastic pipe and 21 feet of coaxial cable, the length of the pipe and diameter is chosen because it works well if using R-G-5-8 coax the ends of the pipe can be sealed after placing a SO-239 connector for your coaxial lead. I use two bolts and solder tags at the other end of the pipe to connect the ends of the dipole to the choke.

When wrapping your coax around the pipe don’t use too much force as it may damage the inner braid and space the turns away from each other by a millimetre or two. R-G-2-1-3 coax around 21 feet used with 5 inch pipe will handle 400 watts pf power. Wire ties can be used to hold the turns together along the length of the pipe. Using these measurements your choke will cover all of the ham radio bands from 1.8 Megahertz through to 28 Megahertz and will keep the radiation pattern.

Using a dummy load connected to the choke and transmitting 100 watts from my transmitter indicated an S.W.R. readings of around 1.5 to 1 at 3.5 Megahertz when testing 28 Megahertz the S.W.R. reading came down to 1.1 to 1 which is an excellent match. Using the choke as it should be at the feed point of a dipole cut for 40 metres give an S.W.R. reading of 1.2 to 1. The highest reading was 1.5 to 1 when using 18 Megahertz but the rest of the High frequency bands gave me very acceptable matching.

By
John Allsopp G4YDM
https://g4ydm.blogspot.co.uk/

Article Source:
http://EzineArticles.com/expert/John_Allsopp/1925417

Article Source:
http://EzineArticles.com/9615600