Monthly Archives: December 2015

How to use the SDRPlay RSP as a panadapter

SDPlay-RSP

In this post, I will show you how to use an SDR as a panadapter for a commercial communications receiver. I’m using an Icom R72 and a SDRPlay RSP, but you can do it with nearly all receivers and SDRs.

The Icom R72 is a double conversion HF (0-30 MHz) communications receiver.

A panadapter lets you see the spectrum of your receiver (it gives you a broader, higher-level picture of what’s around your tuned frequency). After using it, you’ll wonder how you’ve been using your receiver without a spectrum display! 🙂

Almost all the radios we use are of superhetrodyne type. To connect a SDR to the radio, you should first find its 1st IF mixer output (if it has more than one Intermediate Frequency stage).

To find it, the best way is to consult the service manual. The first IF of Icom R72 is 70.4500 MHz, so we can use RTL-SDR dongles too.

Here’s a part of R72’s schematics, extracted from its service manual:

IC-R72-Schematic-Mehdi-Asgari

Look at the R82 resistor; it’s located at the output of first IF stage, so I soldered a connector to its pins (its other pin is connected to the ground)

Between the R82 resistor and the output, we’ve added a series 470-ohm resistor (to prevent loading the IF stage)

Click to enlarge.

The other side of this connector is connected to the antenna input of my SDRPlay RSP.

Now I can view my spectrum on a PC.

Here’s a screenshot of CubicSDR on Mac OS X (you can use other apps like HDSDR, SDR Console, etc.):

CubicSDR-Screenshot-Mehdi

Although this post was about the SDRPlay RSP and Icom R72, this procedure can be done for almost any combination of receivers and SDRs provided that your SDR covers the frequency of first IF stage.

Also, don’t forget that you should tune the SDR to the frequency of IF–in this case: 70.4500 MHz.

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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eBay find: Mullard Meteor 600A

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Mullard-Tube-Radio-Bakelite-1 Many thanks to SWLing Post reader, Monti, who knows that I have a serious affinity for 1940s era receivers. Monti writes from his home in Australia:

I had to send you this link Thomas. I’ve never seen this model before but what a stunning shape for a 40’s piece.

Look at this on eBay:
Mullard Meteor 600A Vintage Art Deco Bakelite Valve Radio c.1947

Lovely! While I could never pay $485.00 AUD for a non-working radio, I can certainly appreciate this gorgeous and unique design with radiating speaker grill louvres.

Check out this beautiful “meteor” dial:

Mullard-Tube-Radio-Bakelite-2

What a stunning radio!

Here are a few more pics I snatched from the eBay listing:

Mullard-Tube-Radio-Bakelite-3 Mullard-Tube-Radio-Bakelite-5

Mullard-Tube-Radio-Bakelite-4

Mullard-Tube-Radio-Bakelite-6

Thanks for sharing, Monti!

Any lucky SWLing Post readers in Australia or New Zealand own one of these Mullards?

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Phil’s initial impressions of the Degen DE27

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Degen-DE27

Many thanks to SWLing Post reader, Phil Ireland, who comments:

I’ve just received my Degen DE27 from China. Interesting little radio, I haven’t had a good chance to put it through its paces yet but my initial impressions are the radio seems well built and fairly intuitive to turn it on.

However, all the instructions are in Chinese so luckily there was someone in my office who could set the language to english otherwise, setting up the radio is a nightmare! I will have to take the radio outside to test its performance as the office environment is useless to listen in.

The box says the radio tunes from 3.2 mhz to 21.850 mhz however, I havent been able to work out how to make it tune out of the standard SW Broadcast Bands yet. Toggling between 10 khz and 9 khz steps for AM is easy as it setting the FM band coverage but I’m yet to determine the SW settings. It appears tuning is only in 5 khz as well on SW.

As for venturing into MP3 settings and recording, I’ll leave that, it seems too much of a challenge! The clock and calendar, sleep timer, alarms are all fairly straight forward but there is an “E-Book” setting which defies description! It has a USB flash disc function and inputs for a micro SD card. Charging the supplied Lithium battery is via a supplied USB cable.

The display is easy to read and attractive with excellent backlighting. I’m not expecting stellar performance on any band, after all, it was a cheap radio (about 40 AUD with free postage) but it is built around DSP architecture. Only a single bandwidth is available and there is no SSB capabilities. The radio hopefully will be ideal to throw onto a backpack or pocket as a travel portable.

If DEGEN read these comments, perhaps an English manual put online would be extremely helpful to allow users to get the most out of the DE27.

I’ll comment more on the performance later but for now, the radio shows promise.

Thanks so much for sharing your initial impressions, Phil! Please keep us informed as you discover more about this little radio!

This reminds me that I have yet to put my Degen DE221 through the paces. Stay tuned!

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Dave reviews the Yaesu FT1XD

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SWLing Post contributor, Dave Zantow (N9EWO), has completed a review of the Yaesu FT1XD (FT1XDR) “System Fusion” Digital-Analog Handheld Transceiver.

The FT1DX 2 meter/440 HT provides both analog and digital communications on both bands with up to 5 watts. It also has wideband receiver that covers from 500 kHz to 999 MHz (US version, less cellular) including the AM and FM broadcast band. It even has a built-in ferrite bar for mediumwave/AM reception.

What does Dave think?

Click here to read Dave’s full review.

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