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member-projects:g4klx-23cms-eme [2025/03/28 16:54] – g4klxmember-projects:g4klx-23cms-eme [2025/03/29 18:07] (current) – g4klx
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 Luckily I had bought one of these dish feeds already so I just needed to find it in my storage unit, which I managed to do. Luckily I had bought one of these dish feeds already so I just needed to find it in my storage unit, which I managed to do.
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 +{{:member-projects:img_2487.jpeg?200|}} {{:member-projects:img_3187.jpeg?200|}} {{:member-projects:img_3188.jpeg?200|}}
  
 ** The Power Amplifier ** ** The Power Amplifier **
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 This was purpose designed by Dave G0LBK. It is similar in design to the ones used to hold a satellite dish on flat roofs and weighed down with slabs. This one was designed to be much heavier duty and is fabricated out of 50mm steel scaffold pole and angle iron, and weighed down by almost 360 kg of concrete slabs. It is very stable. My wife painted it in green Hammerite. The mount is designed to be "temporary" with no permanent mounting into the ground for move to a later location, and maybe to help with planning permission issues should they arise. This was purpose designed by Dave G0LBK. It is similar in design to the ones used to hold a satellite dish on flat roofs and weighed down with slabs. This one was designed to be much heavier duty and is fabricated out of 50mm steel scaffold pole and angle iron, and weighed down by almost 360 kg of concrete slabs. It is very stable. My wife painted it in green Hammerite. The mount is designed to be "temporary" with no permanent mounting into the ground for move to a later location, and maybe to help with planning permission issues should they arise.
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 +{{:member-projects:35ff6dcd-f087-41ff-a2d8-48b82dd0cdd6.jpg?200|}}
  
 The dish feed is hung in front of the dish on the end of two glass fibre square section poles, and with ropes holding the end for stability. The dish feed is held firmly by cut and carved (!!) wooden blocks and lengths of M6 threaded rod. All of these threaded rods have been kept away from being a multiple of a quarter wave in length to remove any interaction with RF. Therefore the only bits of metal in the view of the dish are the Septum Feed and the co-ax, and nothing else. The dish feed is hung in front of the dish on the end of two glass fibre square section poles, and with ropes holding the end for stability. The dish feed is held firmly by cut and carved (!!) wooden blocks and lengths of M6 threaded rod. All of these threaded rods have been kept away from being a multiple of a quarter wave in length to remove any interaction with RF. Therefore the only bits of metal in the view of the dish are the Septum Feed and the co-ax, and nothing else.
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 This was my own design, and is in many ways the heart of the EME system. It's based on an Arduino Uno and the four relay Arduino shield, the [[https://github.com/g4klx/Sequencer|sketch]] is available from my GitHub. It has two transmit inputs and controls three relays, with timings of around 30ms between each. This was my own design, and is in many ways the heart of the EME system. It's based on an Arduino Uno and the four relay Arduino shield, the [[https://github.com/g4klx/Sequencer|sketch]] is available from my GitHub. It has two transmit inputs and controls three relays, with timings of around 30ms between each.
  
-Its job is to control the transmit and receive change over for the RF relays, the power amplifier, and the radio itself. The basis of the design is that the transceiver does not control the transmit/receive changeover, so that it is guaranteed that the rest of the system is changed over first. This means that the signal to change over comes from either a toggle switch on the front of the sequencer box or via a serial port from WSJT-X. The radio being the last to be switched.+Its job is to control the transmit and receive change over for the RF relays, the power amplifier, and the radio itself. The basis of the design is that the transceiver does not control the transmit/receive changeover, so that it is guaranteed that the rest of the system is changed over first. This means that the signal to change over comes from either a toggle switch on the front of the sequencer box or via a serial port from WSJT-X. The radio being the last to be switched. The serial port transmit control from WSJT-X goes via a [[https://radio.g4hsk.co.uk/2020/03/01/enhanced-usb-to-serial-ptt-interface/|G4HSK PTT opto-isolator]].
  
 The sequencer lives in a 2U rack mount case alongside 12V and 24V power supply for the relays and pre-amplifiers, and a co-ax relay used to switch the IC-905 RF between transmit and receive. The sequencer lives in a 2U rack mount case alongside 12V and 24V power supply for the relays and pre-amplifiers, and a co-ax relay used to switch the IC-905 RF between transmit and receive.
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 +{{:member-projects:img_1938.jpg?200|}}
  
 ** Sundry Bits and Pieces ** ** Sundry Bits and Pieces **
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 All RF relays are powered in receive mode to ensure that a loss of power puts everything into a safe mode and doesn't have any transmit RF going into the pre-amplifier for example. All RF relays are powered in receive mode to ensure that a loss of power puts everything into a safe mode and doesn't have any transmit RF going into the pre-amplifier for example.
 +
 +Much of the hardware sits in a wheeled 16U rack mount case which is moved into position when needed. My shack is on the wrong side of the house for EME operation and so EME operation is done from a conservatory and apart from the rack mount, the rest of the equipment sits on a dining table when in operation.
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 +{{:member-projects:img_3192.jpeg?200|}} {{:member-projects:img_3194.jpeg?200|}}
  
 ** The Software ** ** The Software **
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 An extra program is also used for band monitoring named QMAP. It takes the output of an SDR and can monitor almost the whole of the EME section of the band for activity and lists all of the QSOs and CQs that it can detect. It is about 2dB less sensitive than the full WSJT-X program, but is an invaluable tool. I use an AirSpy SDR feeding into SDR Console and that feeds into QMAP, between the SDR and the pre-amplifier is a 3dB splitter and my old pre-amplifier being used as a rather over engineered gain block. An extra program is also used for band monitoring named QMAP. It takes the output of an SDR and can monitor almost the whole of the EME section of the band for activity and lists all of the QSOs and CQs that it can detect. It is about 2dB less sensitive than the full WSJT-X program, but is an invaluable tool. I use an AirSpy SDR feeding into SDR Console and that feeds into QMAP, between the SDR and the pre-amplifier is a 3dB splitter and my old pre-amplifier being used as a rather over engineered gain block.
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 +{{:member-projects:img_3193.jpeg?200|}}
  
 Feedback on operation is done via the [[https://logger.hb9q.ch/|HB9Q EME Logger]]. Other EME software is available, most notably from [[https://www.vk5dj.com/doug.html|VK3UM]] (SK). Feedback on operation is done via the [[https://logger.hb9q.ch/|HB9Q EME Logger]]. Other EME software is available, most notably from [[https://www.vk5dj.com/doug.html|VK3UM]] (SK).
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 The results have been spectacular. I expected EME to be a struggle, and it sometimes is, but not a lot of the time. I started on my first evening running 150 Watts, the old pre-amplifier, and a linear dish feed. This latter item means that I started with a 3dB penalty immediately compared to most other operators. As was right, my first EME QSO was with Dave G0LBK, with no stress whatsoever. The sked was arranged via WhatsApp, but all information was exchanged via the moon. On that first night I worked 13 different stations! The results have been spectacular. I expected EME to be a struggle, and it sometimes is, but not a lot of the time. I started on my first evening running 150 Watts, the old pre-amplifier, and a linear dish feed. This latter item means that I started with a 3dB penalty immediately compared to most other operators. As was right, my first EME QSO was with Dave G0LBK, with no stress whatsoever. The sked was arranged via WhatsApp, but all information was exchanged via the moon. On that first night I worked 13 different stations!
  
-By the next night I had replaced the pre-amplifier with the lower noise one, and proceeded to work a total of 65 unique stations in my first week of operation with my compromised system. For the next period of operation I had replaced the dish feed with my Septum Feed and slowly increased my power to 300W or so. By March 2025 I had worked 133 unique stations off the moon, in all continents, in 102 grids, and in 37 DXCC entities. I think I have worked 15 US states.+{{:member-projects:img_2344.jpeg?200|}} 
 + 
 +By the next night I had replaced the pre-amplifier with the lower noise one, and proceeded to work a total of 65 unique stations in my first week of operation with my compromised system. For the next period of operation I had replaced the dish feed with my Septum Feed and slowly increased my power to 300W or so. By March 2025 I had worked 133 unique stations off the moon (known as initials), in all continents, in 102 grids, and in 37 DXCC entities. I think I have worked 15 US states. 
 + 
 +{{:member-projects:23cms-march-europe.png?200|}} {{:member-projects:23cms-march-na.png?200|}}
  
 WSJT-X incorporates an Echo mode which transmits short pulses and detects the echo, and I can usually see returns of around -19dB (in a 3kHz bandwidth) which is more than enough to be able to work myself, if that were possible. Indeed I have worked many people running systems similar or smaller than mine. The smallest station that I have worked is G0HIK with two 33 element yagis, OE3JPC who uses two 56 element yagis is also regularly worked when the path loss is low. WSJT-X incorporates an Echo mode which transmits short pulses and detects the echo, and I can usually see returns of around -19dB (in a 3kHz bandwidth) which is more than enough to be able to work myself, if that were possible. Indeed I have worked many people running systems similar or smaller than mine. The smallest station that I have worked is G0HIK with two 33 element yagis, OE3JPC who uses two 56 element yagis is also regularly worked when the path loss is low.
 +
 +An invaluable resource for EME operations above 2m is the 432 and Above EME Newsletter. The [[https://eme.radio/|eme.radio]] site is more than just the home of this newsletter and its archives and is highly recommended.
  
 ** The Future ** ** The Future **
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 A potential problem is the results of WRC-23 which may have a huge impact on EME operation on 23cms, but at this time no-one knows for sure what it may be. In the extreme case I, and many others, may have to pack up on 23cms and look at getting going onto 13cms. This wouldn't be the most difficult change, the IC-905 can easily accommodate it, and the sequencer and relays would operate on 13cms without modification, but it would be an unwelcome termination of activity on 23cms, a band I have been active on since 1985. A potential problem is the results of WRC-23 which may have a huge impact on EME operation on 23cms, but at this time no-one knows for sure what it may be. In the extreme case I, and many others, may have to pack up on 23cms and look at getting going onto 13cms. This wouldn't be the most difficult change, the IC-905 can easily accommodate it, and the sequencer and relays would operate on 13cms without modification, but it would be an unwelcome termination of activity on 23cms, a band I have been active on since 1985.
  
 +{{:member-projects:img_3098.jpeg?200|}}
member-projects/g4klx-23cms-eme.1743180849.txt.gz · Last modified: 2025/03/28 16:54 by g4klx