4X4XM^QRZ, Doron

Thank you for visiting this website.   I hope you enjoy reading it and benefit from the resources given.

Topics: * Preface * Current Rig * Ham Activities * 1965 QSL * Vintage Rig * Education * Professions * Interests * Websites * Networks

Being a radio amateur involves creating connections and friendships with individuals you may never meet otherwise. This hobby inspired me to learn about science, technology and social issues through study and experience. Following my retirement, I try to give back to the hobby.

In light of the current 25th solar cycle, I've been thinking about forecasting skywave propagation. Space technology, Software-Designed Radio (SDR), and the internet have aided my study.

Since July 2022, I've been posting new chapters covering HF skywave propagation. The visitor's inquiries fueled my motivation to continue learning and updating this project. See the evolving table of contents.

Name: Doron.   QTH: Karmiel, Israel. My current rig (2020-24) is fairly basic. Everything is SDR and QRP in tiny. (See Vintage Rig) Malachite SDR2 v2.4 Receiver 10KHz-2GHz DSP 3.5" touch screen Malachite SDR v1.3 Receiver 50KHz-2GHz DSP 3.5" touch screen Belka 0.1-31 MHz pocket SDR developed by Alexander Buevsky, EU1ME connected to Magnetic Loop Antenna K-180WLA 70cm diameter Battery Powered 20 dB amplifier Frequency range 0.1-180 MHz   Tecsun PL-330 RX LW, MW, SW(SSB), FM Specifications  Meanwhile, I am a casual FT8 reporter, playing with a 11-band QRP uSDX Transceiver 160, 80, 60, 40, 30, 20, 17, 15, 12, 10 and 6 m. I plan to erect efficient transmission antennas above my home that meet the restrictions imposed by my community. Due to the current security situation in Israel (since October 7, 2023), I am no longer available for a scheduled QSO. As a child, I was fascinated by the "radio miracle" after hearing about radio amateurs wishing to save lives or assist society. My curiosity grew after watching the movie "If All the Guys in the World"; French: "Si tous les gars du monde" A French fishing boat crew in the North Sea eats contaminated food, making them unable to continue their duties. The story focuses on the attempts of a global group of amateur radio operators to deliver an antidote. A few years later I got the desired operating license, Novice in 1964 and General in 1965. 4X4XM enjoying a field day in 1967 Rig: Drake R-4A HF RX attached to SCR522 VHF TRX In 1992, I took a break due to my family's needs, and returned to ham radio in June 2020, after a 28-year absence.

My First Homemade QSL 1965 My birth surname was Tirkel rather Türkel. I changed it to Tal in 1969. back side of the QSL card

  Vintage Rig:

Until 1964 (age 17), my entire rig was homebrew. Then 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.

In 1964, I bought a second-hand commercial receiver, a Hallicrafters SX-110. It was a single conversion (I.F. 455 kHz) general coverage receiver in four bands ranging from 535 to 34000 kHz. I have added a Product Detector (ECH81) and replaced the Noise Limiter with a Noise Blanker US 3,195,052 patent. A year later, I added an external Xtal-controlled front-end that converted the higher HF and VHF bands, down to 3.5, 7, or 10.7 MHz with 50Hz stability and image rejection greater than 75 dB. It was considered a remarkable achievement at the time.

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.

In the same year (1966) I fixed a 19 years old broken Hallicrafter S-37, 130-210 MHz Single Conversion VHF receiver (I.F. 18 MHz) found in a junkyard. This was a true gem that enabled me to search for spurious signals, listen to (audio of) TV channels (from Israel, Cyprus, Lebanon, Jordan, and Egypt), 2m ham radio, civil and military aircrafts, ships, and police. I have operated this amazing receiver from 1966 to 1970.

At the same time I refurbished and modified a ground based SCR-522 WWII transceiver, originally covering 100-156 Mhz in 4 preselected channels. Related versions: UK Airbourne Transceiver; USS Pampanito. General Instructions: 1944 handbook SCR-522 WWII transceiver Assembly in Rack The BC625A transmitter and BC624A receiver were both Xtal controlled. The VHF front-end receiver was fed into any HF receiver that operated on 10.7 MHz. This configuration allowed easy tuning, clear and stable reception of CW and SSB modes on the 2 meter band. The following picture shows such operation during a field day in 1967. The I.F. output of the VHF front-end (BC624A) was fed into the HF receiver (Drake R-4A).

A 16dBi pseudo-horn antenna enabled S9+ AM QSOs on the 2 m band between Haifa, Israel, and Larnaca, Cyprus, spanning 270 kilometers across the Mediterranean Sea. This antenna was constructed from an aluminum expanded 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 were aligned at a 60-degree angle.

The next decade 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. Modification were added to improve operations. Various wire antennas allowed flexibility in 5-band HF operation around the clock. 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. Antenas used: Classic GP, Ringo Ranger, and 2-el Quad at home; 5/8 mobile. 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 to the Voice of Israel on HF every day from New Jersey, USA.

While operating this Swan-350 living in Plainsboro, New Jersey, USA, I kept contacts with Israel using camouflaged vertical antenna. Fortunately, cycle 22 of the sunspots was at its peak at that period.

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:

• Since 1960: have engaged in amateur radio, focusing on learning and experience.
• 1964-1975: operated CW short QSOs and phone ragchews on technical issues.
• 1975-1988: provided phone patches to Israeli radio amateurs who were abroad on duty to allow them to keep in touch with their families back home.
• 1983-1990: operated Packet Radio, HF/VHF X.25 (later AX.25).
• Since 1988: Investigating the increased mortality in amateur radio operators; published in 1988.
  Three of my friends, Yossi 4X4NE (1935-1976), David 4X6JQ (1936-1983), Tzvi 4X1KT (1938-1993), have passed away due to RF overexposure.
• Since 2004: - specialized on EM Radiation Hazards^Hebrew, Environmental Protection, and Public Health.
  1. What does radiation do to our body? ^Hebrew Google translation from Hebrew into English
  2. RF Radiation and EMF Safety (ARRL since 2010)
  3. Safety in the Shack (RSGB since 2014)
  4. Indirect RF Hazards (AF5NP 2018)
• In June 2020, I made a comeback and learned new theoretical material, focusing on SDR, WebSDR, and new topics about HF propagation conditions, forecasting, and simulation.
• In July 2021, I started researching: How does solar activity affect HF propagation?
• In May 2022, I focused on forecasting HF propagation.
• In April 2023, I started chats with AI bots: ChatGPT learned about forecasting tools for radio amateurs.
• Since April 2024, I have been upgrading this site, which focuses on understanding HF propagation.

Interests NOT related to Radio Amateur

• Family: Married to Ilana since 1974, raising four children and seven grandchildren.
• Social Justice, Political Correctness since 1994, Focus on the Abuse of Power
• Genealogy: Searching family roots; since 1997 using internet resources.
• Cooperation and Regulation of Israeli Civil NGOs since 2007
• Israeli Singing Groups since 2012

     Websites NOT related to Radio Amateur:

• Stop The Abuse of Power, since 1994 (an emphasis on IARC [Hebrew: אגודת חובבי הרדיו בישראל Google Translate])
• PEACE & TOLERANCE. since 1997
• The Turkel Tribe website traces family roots more than 350 years ago.
• Voluntary activity aimed to improve our society; see Doron Tal's Homepage

     Public Networks:

• Youtube playlists some relevant to our hobby: Radio Amateur, Solar Physics (Heliophysics), uSDX, and HAARP
• Facebook focus on Radio Amateurs
• Linkedin - login is required to view

    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

Visits since 17 August 2022