Tag Archives: Mehdi Asgari

What is the cheapest radio?

I assume people who read this blog have so many things in common, one of them is a love for gadgets, especially radios and SDRs. To others, a radio is a radio, but not to us. We invest so much money and time to obtain and play and experiment with different tools and compare them. I have had so many SDRs and some traditional radios (not as much as Thomas, though) and I really get the best that I can afford for my needs.

But one day walking in a local electronics shop in Berlin/Germany, a small radio caught my eye, not because it was any special or different than other pocket-sized radios, but because of its price tag. It was the first time I had seen a single digit price for a radio!

I bought it without hesitation, for 9,99€ and later I realized it’s even cheaper in Austria: 6€ !

I’m talking about “ok. ORF 110”, an AM/FM radio running on two AAA batteries and using analog knobs and no display. Nothing special can be found on this little device; It has power on/off button, AM/FM band switch, volume knob, analog frequency knob, earphone socket and an internal telescopic antenna with a maximum 18cm length. And it does even come with 2 years of warranty.

The first thing that I did was compare it with my beloved portable radio: the Sony ICF-SW100, and I must say that I’m amazed. This little radio is on-par with Sony on FM; Unfortunately I can’t receive any AM signals from my apartment, so there wasn’t much that I could test there. But overall I’m really satisfied with the reception and audio quality. This can be a good companion for anyone who wants to have a cheap backup radio.

Here’s the link to the product: https://de.ok-online.com/de/radios/radios/orf-110.html

I wonder if you know of anything even cheaper? I would love to see and try what would be the cheapest (I haven’t searched the Chinese websites though. I was looking for something that I can buy here in Europe without spending on shipping or customs).

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Ham Radio Friedrichshafen 2018 Flea Market Photos

Many thanks to SWLing Post contributor, Mehdi Asgari (DF2HF / NM9A), who shares photos from the 2018 Friedrichshafen ham radio convention flea market. Be sure to also check out photos we posted yesterday of Friedrichshafen vendors. Thank you, Mehdi!


Ham Radio Friedrichshafen 2018 Fea Market Photos

by Mehdi Asgari (DF2HF)

Mehdi is a software engineer and SDR lover working in Berlin. He’s a licensed ham (DF2HF & NM9A) and also a member of EP2C club.

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Ham Radio Friedrichshafen 2018 Vendor Photos

Many thanks to SWLing Post contributor, Mehdi Asgari (DF2HF / NM9A), who shares photos from the Friedrichshafen ham radio convention this year. Tomorrow, we’ll post his photos of the flea market area!


Ham Radio Friedrichshafen 2018

by Mehdi Asgari (DF2HF)

Mehdi is a software engineer and SDR lover working in Berlin. He’s a licensed ham (DF2HF & NM9A) and also a member of EP2C club.

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Photos from an EP2C field event

EP2C-photo_2016-07-17_18-28-59

Many thanks to SWLing Post contributor, Mehdi Asgari, who writes with news from his amateur radio club (EP2C):

EP2C-photo_2016-07-17_18-29-10

We had a one-day [amateur radio] program on July 16, 2016.

EP2C-photo_2016-07-17_18-28-32

Our club organized an activity from 5:00 AM local time to 8:30 PM (local time) in Karaj’s heights (50 km of Tehran).

EP2C-photo_2016-07-17_18-29-48

We had a vertical for 15 and 20m, an Inverted-Vee for 15 and 20m and a Magnetic loop (can be tuned from 10 to 22 MHz).

EP2C-photo_2016-07-17_18-29-14

We operated two bands (mainly 20m and some 15m), both SSB and CW.

EP2C-photo_2016-07-17_18-29-25

Propagation was not very good but we managed some good DX contacts (East of USA: Michigan, New Jersey, Ohio, etc, Japan, Canada, …).

EP2C-photo_2016-07-17_18-28-47

EP2c-photo_2016-07-17_18-28-43

Antennas were made by us and we used two rigs (Icom 735 for CW and Elecraft K3 for SSB).
It was also an educational program for enthusiasts and beginners.

Cheers
Mehdi

EP2C-photo_2016-07-17_18-28-52

Thank you so much, Mehdi, for sharing EP2C special event!

I imagine your field station attracted a lot of attention on the DX Clusters and I bet you were on “the other end” of more than one pile-up despite the bad propagation.

Your club also used two great field radios: the benchmark Elecraft K3 and  the Icom IC-735. Two radios from two completely different eras! I imagine the age gap between the two was pushing three decades. The IC-735 was my first ham radio transceiver. Though it’s an older rig, it holds its own in the field and has proven itself reliable (the ‘735 also had one of the better general coverage receivers of the era). Of course, the Elecraft K3 has become the DXpeditioner’s choice transceiver due to its performance, versatility and efficiency.

Thanks again for sharing your event with us, Mehdi.  I hope to hear EP2C on the air again very soon!

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First Iranian ham radio contest

Iran-Map

To celebrate 37th anniversary of Iranian Islamic revolution, the first Iranian ham contest is going to be held on February 1st, 2016 and will last for 10 days.

Objective: To encourage and increase contacts (especially DX ones) with Iranian radio amateurs.

Dates:

Contest Period: 10 days (Feb 01, 00:00 UTC – Feb 11, 23:59 UTC)

All modes (CW, SSB, RTTY) can be used on this period.

Bands:

40, 20, 15 and 10 meters

Note: On 20m, the upper limit is 14.250 MHZ

Contact information:

For contest information and any sort of inquiries contact epcontest.2016@gmail.com

Certificates:

Certificates will be awarded to:

1- Top single operator (at least 30 contacts on all modes)

2- Top CW operator

3- Top SSB operator

4- Top RTTY operator

5- Any operator who contacts at least 3 Iranian hams

Getting QSL card:

If you need the printed certificate, you should send 5USD (or equivalent in your          currency) to this address: “P.O. Box 14185-736 , Tehran, Iran”

Please use registered mail to make sure it delivers without problems.

WebMoney and Bitcoin are also accepted. (Contact us for more information)

Misc:

Iranian amateurs will use “/contest” at the end of their call sign for this contest.

The deadline for contacting us for certificate is 3 months after the contest.

List of Iranian participants:

  1. EP2FM  : Abdollah Sajjadian
  2. EP3RB : Reza Batebi
  3. EP3AG  : Ali Ghanbari
  4. EP2FA   : Farman Aghdasi
  5. EP2CM : Jamshid Mansoori
  6. EP4HR  : Hamid-Reza Rahimi
  7. EP3MIR : Mohammad Mobini
  8. EP3CQ : Ali Solh-Joo
  9. EP2LMA : Mohammad Azimi
  10. EP2LSH: Saeed Shokrollahi
  11. EP2HZM : Hassan Zohoorian
  12. EP2HEK : Hekmatollah Rahimi
  13. EP5MKN : Majid Kiani Nejad
  14. EP5ABD : Bagher Mir-Abdolhagh
  15. EP7AHN : Hamed Nahrir
  16. EP4KHA : Amin Kharadmehr
  17. EP4MMM : Mohammad Mirab
  18. EP2MA : Mohammad Ameli
  19. EP2LSD : Sepehr Dalir
  20. EP3EEE: Ehsan Esteki

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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Icom IC-R72: a repair story

Icom-IC-R72-Front-Mehdi-AsgariIn this post I’m going to tell you how I repaired my Icom IC-R72 receiver. Although it’s about a specific device, the logic and methodology applies to all radios.

I bought an Icom R72 from a friend for about $200. At first, I just checked 7.0MHZ (40 meter band) and 21.0MHZ (15 meter band) and it was OK. After some time, I tried to listen to some ham radio on 20 meters (14.0MHZ) and it was deaf! I checked everything: antenna connectors, balun…everything.

With some trial and error, I found out that it was deaf from 11-15 MHz. With the help of the members of “Icom R72” Yahoo Group, I found one of the usual suspects: bandpass filters’ switching diodes.

I took a look at the service manual and apparently this radio uses multiple bandpass filters  for different  frequency ranges.

Schematic-Icom-R72-1

As you see in the above picture (grabbed from service manual), one of the bandpass filters is for 11-15 MHz range–that’s the range where my radio was deaf.

Note that there are multiple ways to test that a radio is deaf at a frequency. One of the simplest ways: connect an antenna or even a long wire to the antenna socket of radio. The noise level should increase; if not, there’s a problem.

Schematic-Icom-R72-2

After testing diodes with a multimeter, I found out that D31 is faulty. Almost all multimeters have a diode-test functionality.

I replaced it. The original diode was 1SS53, but I used a 1N4148 which is very common and found everywhere. Now I have a working radio! 🙂

If you have a radio that’s deaf at a frequency range, there is probably a problem in bandpass filters.

Here are some internal pictures of my Icom IC-R72:

IC-R72-Internal-IF-Stage-Mehdi IC-R72-Board-1 IC-R72-Board-2 Icom-IC-R72-Open

I should thank my friend and electronics mentor, Saeed (EP2LSH) who always helps me in my electronics adventures.

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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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)

IC-R72-Internal-IF-Stage-Mehdi

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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