Category Archives: Antennas

The Panasonic RF-B65: the legendary portable with a cult following amongst DXers

Hi there, back in 1990 I was given a Panasonic RF-B40 for my birthday (I think it was my birthday…1990 was a long time ago!). I found that radio to be very sensitive on shortwave, more so perhaps than my Sangean ATS-803A, but ultimately it didn’t really add much value to any serious DXing because it would only tune on shortwave in 5 kHz steps. This rather course tuning arrangement was very limiting in terms of tuning out adjacent noise and copying tropical band – and other signals that weren’t quite on-frequency etc. Frustrated, I lent my RF-B40 to my brother a few years ago and serves me right; following a house move, he managed to lose it! Quite a shame really because almost three decades later, I would have been very interested to put the RF-B40 through it’s paces on a DXpedition or two. You really don’t see them in action very often at all these days.

Above: the Panasonic RF-B40 (not mine – unfortunately) and the RF-B60, mid-DXpedition!

At that time, which was around the beginning of the 1990s, I read a review somewhere and it became clear that the better receiver was quite obviously the RF-B65. Upon it’s introduction into the market, the RF-B65 was immediately recognised as an excellent receiver, however, in the intervening years it’s reputation has continued to grow to the point today where it enjoys legendary status amongst DXers and bit of a cult following. There’s a lot of information on the RF-B65 to be found on the internet, so I won’t go into huge detail, but the obvious question is: what makes thsi receiver so special? Well, it’s a quite compact PPL double conversion receiver, covering 153 kHz to 29,999 kHz AM and 87.5 to 108 MHz, FM. It has a keypad for direct frequency input, although you have to press either the ‘FREQ’ or ‘METER’ buttons prior to punching in the numbers to define whether you wish to access a particular frequency, or band. I actually find that slightly annoying, but you easily learn to live with such trivial matters when using a radio of this quality and performance.

Furthermore, there’s an electronic signal strength meter, a DX/local attenuation switch, external antenna jack, SSB reception mode, 1 kHz tuning steps on shortwave (unlike it’s little brother the RF-B40) and fine tuning. The single bandwidth filter is 6 kHz wide and thus limits selectivity a little, although the SSB option and fine tune helps offset that somewhat. It would have been nice to have a couple more filtering options, particularly narrower for serious DXing in crowded bands, to combat adjacent channel QRM. Build quality is generally excellent as you would have expected from a high-end Panasonic portable and with a very compact form-factor – roughly the size of a paperback book and weighing in at just 1.4 Ibs, it is eminently more portable than a Sony ICF-SW77 or the iconic ICF-2001D/2010.

Ultimately, the RF-B65 continues to enjoy an excellent reputation today, nearly 30 years after it was introduced because it is a wonderfully sensitive receiver and arguably the best-ever performing shortwave portable in the paperback book size category – often touted as ‘travel portables’. I managed to acquire an example in as-new condition from eBay, although mind you, I paid through the nose for it lol – that cult following ensures prices remain very robust! I have tested my example against the equally legendary Sony ICF-2001D, still considered by many to be the benchmark for shortwave portables, and in my experience the Panasonic is right up there with it. There’s virtually no difference whatsoever in sensitivity. Where the Panasonic comes a little unstuck is the lack of bandwidth filtering and SYNC, leading to lower selectivity. However, clever use of SSB and fine tuning does provide quite good compensation for these shortcomings. Overall though, given it’s size, sensitivity, build quality and audio, as a complete package, in my opinion, the RF-B65 is equal to the ICF-2001D, and this is why today, it remains so highly sought after.

Below are embedded reception videos and text links to the Oxford Shortwave Log YouTube channel, with various DX catches on the RF-B65. Some of these are considered quite rare in Europe, for example EXPPM Radio Educación’s 1 kW signal from Mexico City, the now defunct ABC Northern Territories on 120 metres and Radio Bandeirantes from Sao Paolo, Brazil, amongst others. Please note; right at the bottom of this post is a link to some very recent comparisons with the brilliant Eton Satellit – one of the very best portables currently on the market today. The vintage Panasonic holds its own, despite 30 years of supposed technical innovation in electronics. Thanks for reading/watching/listening and I wish you all great DX.

Click here to view on Oxford Shortwave Log

Click here to view some comparison videos of the RF-B65 and Eton Satellit

Clint Gouveia is the author of this post and a regular contributor to the SWLing Post. Clint actively publishes videos of his shortwave radio excursions on his YouTube channel: Oxford Shortwave Log. Clint is based in Oxfordshire, England.

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Advice on cancelling locally generated noise

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An SWLing Post reader recently contacted me with the following question:

“What devices work well to cancel out local RFI? I’ve been told that both the Timewave ANC-4 and a number of BHI products are all worth considering.”

Unfortunately (or fortunately, for me) I’ve no experience with outboard DSP or noise cancelling devices because I live in such an RFI-free area.

I know this reader already has a Wellbrook Loop, but he’s looking for a way to even increase noise mitigation further at his home listening post.

Post Readers: Can you help guide him? Please comment with your experience. Is a product like the Timewave or BHI the next logical step? If not, what is?

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Using the Sony ICF-SW7600GR with external antennas

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Many thanks to SWLing Post contributor, Steven Crawford, who writes:

As the 7600GR supplies 6v DC to the external antenna jack to power their active loop antennas there seems to be a great deal of confusion on the web about whether one can or cannot use an external antenna such as a random length of wire attached to the center tip of a barrel connector.

I have been unable to locate the blog entry but I seem to remember you discussing this in one of your posts. In it you mentioned you had built a widget that killed the voltage and allowed you to use the external antenna of your choice. I would appreciate your thoughts on a random wire to center tip antenna and details of the widget you built when you have time.

Thank you for your question, Steven. I hope a reader can help point to the post you’ve mentioned. I believe I recall reading this in a guest post–I know I’ve never used a device to kill the 6V phantom load in the antenna out jack.

I suppose I’ve (incorrectly?) assumed the Sony would only push voltage out if connected to the Sony AN-LP1 (see right).

I know I’ve used a number of antennas with the ICF-SW7600GR: long wires, the PK Loop, The EF-SWL, the NASA PA 30, and even a rather large multi-band dipole when I recorded the final broadcast of RNW. I’ve never experienced a problem, nor damaged the antenna/receiver as of yet.

Can anyone shed some light on this? Please comment!

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The Bonito Boni whip: proving to be excellent portable antenna for DXing

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Hi there, if you’re a subscriber to the Oxford Shortwave Log YouTube channel, you will be aware that I have been using a Wellbrook ALA1530 H field antenna, for 15 months or so, with (at times) excellent results. A while back I was on the lookout for a second antenna, however at more than £250, I couldn’t justify purchasing a second Wellbrook. Ultimately I splashed out on the Bonito Boni whip E-field wideband active antenna (20 kHz to 300 MHz) and with a very compact form-factor suitable for DXpeditions/portable operation in general, the Boni whip definitely ticked all the boxes. Furthermore, with reasonable second and third order intercept points of +55 and +32.5 dBm respectively, the Boni whip, on paper at least, looked like a pretty good buy at around £100.

Initial testing at home confirmed, perhaps not surprisingly that the Boni whip could not match the SNR provided by the Wellbrook ALA1530 in a noisy, urban environment. However, less predictably, the Boni whip has proven to be a truly excellent antenna away from the ubiquitous blanket of ‘electrosmog’ at my QTH. Furthermore, it really is so compact, I simply leave it in the car in a small flight case, with a portable and connectors etc. for ad-hoc listening sessions. Since returning from my most recent trip to Brazil, I have had a chance to review my most recent catches with the Boni whip, some of which are realy pleasing and most definitely underline the excellent performance of this diminutive antenna. In particular, signals from Radio RB2 on 11935 kHz and Radio Aparecida on 11855 kHz, both low power Brazilian stations, are testament to how sensitive the Boni whip is in an electrically quiet environment. Check out also the quality of longwave signals from Poland and the Czech Republic – simply amazing for such a physically short antenna. Finally, there’s a personal first from Lusaka, Zambia, Voice of Hope Africa on 13680 kHz. All the more rewarding that this was actually copied in my work office!

I hope you found this article interesting. There are embedded reception videos below and text links for all, which will take you directly to the relevant video on the Oxford Shortwave Log YouTube channel. Thank you for reading/watching/listening and I wish you all excellent DX!

Click here to watch on YouTube

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Tony performs a quick LNA4ALL test

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Many thanks to SWLing Post contributor, Tony Roper, who shares the following guest post which originally appeared on his blog, Planes and Stuff:

Quick LNA4ALL test

by Tony Roper

Despite the best efforts of the Royal Mail service, I have been able to get my hands on a Low Noise Amplifier created by Adam at LNA4ALL. The Royal Mail showed just how useless it is, when the parcel arrived here in the UK in just 11 hours from Croatia on February the 14th, but then not getting delivered to me until March the 14th – yes, one month! There is no surprise that courier companies such as DPD and Hermes are getting more business than the Royal Mail – they are bloody useless.

Anyway, the reason for the purchase is for a later review on an AIS dongle that I will be testing, but which has unfortunately been possibly damaged before getting to me.

So, as I had some time to spare I thought I’d run a quick test on how the LNA performs against the claims that is shown on the LNA4ALL website. For the test I used a quickly built 12v to 5v PSU that was connected to a Maplin bench PSU and also a Rigol DP711 Linear DC PSU where I could ensure a precise power input. As it was, it was good that I used the DP711 because my quick PSU was only chucking out 1.2v at connection to the LNA4ALL, despite an unconnected output of 5v – some work needed there I think.

Despite this lower power the LNA4ALL still worked with just the 1.2v input, though the results where not as good.

Other equipment used were a Rigol DSG815 Signal Generator and a Rigol DSA1030 Spectrum Analyser (no longer available), along with various Mini-Circuits shielded test cables. The Rigol equipment I purchased from Telonic Instruments Ltd last year.

Below then is a table that contains all the relevant data. As you’ll see the Gain claim is pretty much spot on with some being over. Just a couple of frequencies are below that which is claimed, especially at 28 MHz.

LNA4ALL Frequency data

A couple of things to note.

Firstly, somehow I managed to miss testing 1296 MHz. I obviously didn’t put it in the table in Excel before I started ? Also, the DSG815 only goes up to 1.5 GHz so I couldn’t test above that.

Secondly I ran a test for the AIS centre frequency of 162 MHz, for which there was no comparison to the LNA4ALL data. A gain of over 24dB though shows that the LNA would be perfect for those of you with AIS receivers that may want to get better reception. To prove the theory I compared the LNA reception against data without it connected to the NASA Engine AIS receiver that I currently use. In ShipPlotter I average a max range of around 15nm without the LNA, but with it connected this increased to around 22nm. The number of messages received also tripled as it was able to dig out the weaker signals.

The NASA Engine isn’t a bad receiver, but it is a frequency hopper rather than a dual monitor, and so it changes between the two AIS frequencies every 30 seconds (161.975 MHz and 162.025 MHz). I suspect a dual monitor would give better message numbers and range.

Below is a graph made using the excellent software by Neal Arundale – NMEA AIS Router. As you can see the message numbers (or sentences) for over an hour are pretty good – well, it is a vast improvement on what I used to get with my current “temporary” set-up, with 419 messages received in an hour. The software is available at his website, for free, along with various other programs that you can use with AIS. If you’d rather not use ShipPlotter he has created his own AIS Decoder which can be linked into Google Earth and such like. Visit his website for more information.

My antenna isn’t exactly top-notch. It is at a height of just 4 metres AGL in the extension loft, and it is made from galvanised steel angle bead used by plasterers to strengthen corners prior to skimming – this I cut down as a dipole for a target of 162 MHz. As usual with my trimming of antennas, I cut just too much off and ended up with it cut to 161.167 MHz. It gives a VSWR of 1.018 and Return loss of 40.82dB, with 162 MHz being approx. 30dB Return loss which equates to 1.075 VSWR – that will do.

Also, as I live right on the coast, about 50 metres from the sea, I’m practically at sea level, which doesn’t help much with range and signal reception either. Despite this the antenna produces great results, though it is just temporary until I can get a new homebuild up on the roof.

VSWR reading for the homebrew loft AIS Antenna

The LNA4ALL retails at various prices depending on what option you go for. I went for the aluminium box version so it was around £54 including the delivery. I had looked at a Mini-circuits equivalent, and when it looked like the LNA4ALL was lost I did actually order one. But this was nearly twice the price, and seeing as the LNA4ALL contains many components from Mini-Circuit I doubt it is any different really.

All in all the LNA4ALL is all you need to boost your weak signals – couldn’t get any more all’s in ?.

Many thanks for sharing your quick test of the LNA4ALL, Tony! Post Readers: if you’d like to read more of Tony’s work, check out his blog, Planes and Stuff.

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Daytime DX: Gary compares Terk Advantage with homebrew FSL Loop

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Many thanks to SWLing Post contributor, Gary DeBock, who shares the following:

Daytime DX Shootout– a new-design 4.7 inch FSL antenna ($62 construction cost) goes up against the Terk Advantage AM commercial loop ($58 on eBay) in the daytime DX reception of 650-CISL (10 kW at 160 miles, in Vancouver, B.C.).

The first 20 seconds are on the Terk Advantage, and the final 24 seconds are on the new 4.7 inch FSL (using 27 of the commonly available 62mm Russian surplus ferrite bars).

Signal strength is roughly equal, but the FSL’s lower noise advantage gives it the edge.

Click here to download MP3.

Thank you for sharing this comparison, Gary. You’re right: the FSL provides lower noise and a more stable signal to boot. Still, I’m impressed the Terk was able to compete! In terms of commercially-produced loops, the Terk Advantage is certainly a good one.

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Gary’s mediumwave DX FSL antenna phasing experiment

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Many thanks to SWling Post contributor, Gary DeBock, who shares the following note about his latest FSL antenna experiment:

Medium wave DX FSL antenna phasing experiment– 1593-CNR1 (Changzhou, China, in Mandarin) boosted up to strong (S9) peaks by two 5 inch “Frequent Flyer” FSL’s at 1435 UTC on February 25th in my frozen back yard in Puyallup.

Unlike other high gain MW antennas, the FSL’s can provide cumulative gain at very close inductive coupling ranges.