home 4X4XM Personal Bio


Doron is my name. Karmiel, Israel, is where I call home.

I've always been fascinated by radio.

From 1963 to 1992 I was an active amateur radio operator. See my Vintage Rig.

After a 28-year break I returned to amateur radio in June 2020.

Now I'm looking forward to ragchew with both old and new friends.

My present rig is fairly basic. Everything is SDR and QRP in tiny.

Due to the recent 25th solar cycle, I've been thinking about how the Sun affects HF radio propagation.

Thankfully, advances in Space technology, SDR (Software Designed Radio), as well as the internet
have enabled us to study wave propagation in ways I never imagined possible.

As planned, I'm compiling data on HF Propagation Forecasting, doing research, and assessing the findings.

This project is frequently updated. See the table of contents.



Doron Tal is the name that I use today. Before 1969, my surname was Tirkel.

I Started Radio Hamming as a kid in the late 1950's, licensed in 1964 (Novice), and 1965 (General).

Due to a busy life, I was forced to be QRT in 1992 and returned back to amateur radio in 2020, this time to forecast propagation of skywaves.

Current rig:
  1. Malachite DSP v3 Receiver
    50KHz-2GHz DSP; 3.5" touch screen
  2. Belka 0.1-31 MHz pocket SDR
    developed by Alexander Buevsky, EU1ME
  4. Tecsun PL-330 digital RX / Scanner
    LW, MW, SW(SSB), FM
conected to K-180WLA

Magnetic Loop Antenna 70cm diameter
Battery Powered 20 dB amplifier
Frequency range 0.1-180 MHz

I plan to set up effective HF transmitting antennas
that comply with the restrictions imposed by my community.

Meanwhile, I'm a casual FT8 reporter who also enjoys playing with a 10 band QRP uSDX transceiver.

Until recently I was QRV for voice RoIP meetings, Hebrew ragchewing:
   at EchoLink daily 04:30-05:00 UTC
and Peanut Hebrew Room: Tuesday & Thursday 14:00-14:45 UTC.

Due to the security situation in Israel, I am temporarily unavailable at the times specified.

QTH History:
1963-1975  KM72LT - Haifa, Israel
1972           JO21RK - Eindhoven, Holland  (PA9UV)
1975-1984  KM72MU - Q.Yam, Israel
1984-1990  KM72PW - Karmiel, Israel
1990-1992  FN20QH - NJ, USA    (4X4XM/W2) see the rig
 after 1992  KM72PW - Karmiel, Israel

↑      Amateur Radio Activity:

  • 1957 - The movie that changed my life. At the age of 10 years, I became SWL following the French movie
    "Si tous les gars du monde" youtube, wiki, English title: "If All the Guys in the World" Google, wiki.
  • 1964  Novice; within 6 months worked 870 stations in 83 countries, limited to 7065-85kHz; 5W CW homemade rig
  • 1965-1970 CW / AM CW / AM homebrew and modified rig, active on 80, 40, 20, 15, 10 and 2 meters
  • 1966 The first 2m AM QSO from downtown Haifa, Israel to Larnaka, Cyprus, TX: 15W into 16dBi pseudo-Horn Aerial
  • 1970-1972 CW, SSB - All Bands HF, CW, AM, NFM - VHF (2m); unique homemade aerials
  • 1972 July-August  PA9UV - SSB @ Evoluon (Philips), Eindhoven, Netherland
  • 1973-1990 CW, SSB, RTTY, Packet radio, NFM / All Bands - HF, VHF TCP/IP. Developed unique RDF and Gadgets
  • 1981-1983 Co-author of the book, "Fundamentals of Electronics and Communication for Hobbyists" 1983, Israel.
  • 1983 Developed the first CW decoder written in Basic for Commodore 64, TRS-80, Acorn Atom, and ZX Spectrum
  • 1990-1992 operating 4X4XM/W2 from NJ, USA (mainly HF SSB), while on Sabbatical Leave
  • 1992-1997 UHF and SHF experiments
  • 1994- ongoing INterNuT-Radio
  • 2020- Comeback:
↑      My First Homemade QSL 1965
The first homemade QSL of 4X4XM in 1965
Vintage Rig:

↑    Until 1965, my entire rig was homebrew. After 1966, I began modifying vintage and surplus equipment.
See the list below for the gear I've preferred over other gadgets I've collected and used over the years.

Hallicrafters SX-110
In 1966 (age 17) I bought my first commercial receiver, a Hallicrafters SX-110. It was a single conversion (455 kHz IF) general coverage receiver in four bands ranging from 535 to 34000 kHz. First, I added a Product Detector and improved the Noise Blanker. Second, I built an external Xtal-controlled front end that converted the higher HF and VHF bands to 3.5, 7, or 10.7 MHz with 50Hz stability and image rejection of more than 75dB. It was considered a remarkable achievement at the time.

Subsequently I fixed a broken Hallicrafter S-37, 130-210 MHz VHF receiver that I had discovered in a junkyard. This was a true gem that allowed me to search for spurious signals and listen to amateur radio broadcasts, aircraft, ships, and police.
S-37 VHF Receiver

In addition, I refurbished and modified the SCR-522 WWII transceiver,
originally covering 100-156 Mhz in 4 preselected channels.

This antenna was constructed from an expanded aluminum mesh in the shape of two isoscale triangles attached to a rectangular wood pyramid.
The transmitter BC625A and receiver BC624A were Xtal controlled.
I added a 10.7 MHz output to the VHF receiver after the conversion stage, which was injected into the SX-110. This configuration enabled easy tuning within the 2 meters amateur band and stable clear reception of CW, and SSB modes.

In 1966 the late Erik Friedman MD, 4X4WF (SP5WF), lent me Bandmaster Delux TBS-50D Transmitter (Harvey Radio Laboratories, Brookline, Southbridge, MA, USA) covering 80m through 2m.

I have added a homebrew VFO.

Using this transmitter I made thousands of CW and AM QSOs.

16dBi pseudo-Horn Aerial for 2m that was erected in 1966,
enabled S9+ QSOs from downtown Haifa, Israel to Larnaca, Cyprus ~270 Km
This antenna was constructed from an expanded aluminum mesh in the shape of two isoscale triangles attached to a rectangular wood pyramid. The pyrmid's base and the triangles' sides measure 2450 mm. The mesh triangles are aligned at a 60-degree angle.

In 1975 I bought a second-hand Yaesu FT200. It was an SSB/CW transceiver that covered the pre-WARC amateur bands from 80m to 10m and provided up to 180 watts PEP. I added improvements and used it until 1990.

In 1977, I purchased ICOM IC-240, a two-meter FM transceiver, and modified it to double the number of channels by adding two diodes. It was my favorite "Taxi Radio" that I'd ever used; it was simple, cute, and durable.

In 1982, I won a raffle for a broken Siemens E311 receiver. I restored it until it operated like new and used it as a high-quality receiver for eight years in my shack, with an accuracy of 100 Hz and stability of 20 Hz over 24 hours.

While on Sabbatical Leave (1990-1992) in Plainsboro, NJ - the late Sid Gogel, W2FUR (1919-2015) lent me a vintage rig:

This Collins 51S-1 receiver enabled me to listen in New Jersey USA, to the Voice of Israel on HF, and more.
Operating this Swan-350 I kept in contact with Israel during that Sabbatical Leave 1990-1992.

↑ Education: 1977 MSc. Physics (Molecular Physics, Physical Chem., Electro-Optics, Sys Eng.)

Specialties: Scientific R&D, Sys Eng. & Analysis, Management, Planning, Audit, Arbitration, Expert Witness

↑     Professions:

  • R&D Physics 1973-1997 (Laser Systems, Combustion, Night Vision, RDF, IDFF, Artificial Soldier)
  • System Engineering 1982-1997 (Advanced Physical Systems)
  • Project Manager 1987-1990 (Airborne Night Vision)
  • Expert Witness 1997-2014 Speed Enforcement by Lidar & RADAR (SHF)
  • Control Boards - Volunteer member of Audit Committees (NGOs) from 2006 until today

↑      Interests:

↑     Websites:

↑     Public Networks:

↑    Last but not least:

The world is changing as the radio amateur spectrum is being sold off to commercial users since few amateurs operate SHF and above.

If you have comments, questions or requests please e-mail me.

73 de Doron

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