Discover and read the best of Twitter Threads about #AMSAT

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Recently, tens of #amsat ops made their 1st #moonbounce QSO. The thrill of #EME with a biggun creates an illusion of similarity to other modes. EME is different. How small a station you can hear? This thread elaborates on accurate predictions. No magic, only Physics! #hamradio
2/10 #EME is the only field in #hamradio that allows reliable predictions of station sizes that one can work. No smaller station beyond this prediction can be contacted under any conditions! You cannot bend the theory. The link budget can be expressed in Signal-to-Noise ratio-SNR
3/10 SNR represents the ratio of System Gain to Noise Temperature. #WSJTX in Q65 computes SNR in the bandwidth B=2500 Hz. That is the report that you exchange with each other. We want to maximise it by increasing the numerator and decreasing the denominator
#hamradio #moonbounce
Read 11 tweets
This is a simplified guide describing a bare minimum (!) for #EME operation of WSJT-X in Q65-60B on 432 MHz. A few settings are TRX-specific. Consult to your rig's manual for those

Step 1: Download stable version of WSJT-X at

#amsat #moonbounce #hamradio
Step 2: Install WSJT-X and open Settings
1) Fill in "My Call" and "My Grid"
2) Tick "Enable VHF and Microwave submodes"
3) Tick "Decode after EME Delay"
Step 3: Navigate to Radio tab
1) Choose your rig model
2) Choose your serial port and baud rate
3) Choose CAT as PTT
4) Mode and split operation depends on your rig. A minimum non-destructive set: Non and Fake it, respectively
You test CAT by a button
Read 8 tweets
Bernd DL7APV asked me to QSP to the #AMSAT community that he will QRV this coming Thu, Sat, Sun and listen especially for #satellite setups. Use your chance to make your first ever #EME QSO - biggest challenge in #AmateurRadio πŸŒ—

See how this can be done⬇️

#hamradio #moonbounce DL7APV and his EME antenna. Credit: DL7APV
Read 5 tweets
If you work via #GreenCube, try #EME with big guns. I promise, you will be amazed! As a proof of concept, I made a quick #moonbounce QSO with DL7APV with just a Yaesu FT-818, 40W, 1dB NF LNA and 15 el Diamond antenna held by hand! Easy QSO. Read on🧡
#amsat #io117 #hamradio #hamr Diamond A430S15 Yagi antennaEME QSO with DL7APV using 40W, Yaesu FT-818 and 15 el Yagi
2/9 There are a number of extremely capable #EME stations on 70cm: DL7APV, HB9Q, NC1I. If you are enjoying decode rates above 80% on #GreenCube, don't wait and try #EME. You will likely complete your first QSO over the Moon faster than on the congested #IO117
#amsat #hamradio Credit: HB9QCredit: DL7APVCredit: NC1I
3/9 I used my portable #Greencube set: Yaesu FT-818ND - 40W amp / 1dB NF preamp - Diamond A430S15 14.8dBi on wooden extension, held by hand and pointed visually. With a low NF frontend you can go with a 7el Arrow
#EME #amsat #hamradio #hamr #moonbounce
Read 10 tweets
So, you have only one radio and restrain yourself from LEO sat operations because you don't know how to deal with Doppler?

Or you have two radios and would like to find clear frequency to call, or to find exact frequency where that rare station is listening?

#amsat #dxcc

You know math, right?

And you already have ISS Detector for Android, with those valuable information about passes, paths, Doppler shift for your location?

How to calculate on what frequency you have to call, to be heard exactly where you heard someone calling?

Take a look at ISD Detector info. All you need is there.

Where to transmit? Where to set second VFO or second radio, without hola-holing or whistling around?

Let's say, you found a clear frequency on 435.630, and you would like to call CQ.

Read 6 tweets
LNA / preamp is an unpopular topic of the portable SAT discourse. Noise figure (NF) is assumed to be low due to absence of long cables. But what if NF of the system inherently is not top tier? Any benefit in using LNA with FT-817 & FT-818? 🧡
#hamradio #amsat #amateurradio #hamr ImageImageImage
NF & MDS are determined by the quality of the signal chain and the venerable FT-818 is not a star in that department. Under exact same conditions (antenna, cable etc) a very weak signal readable from IC9700 would not be copyable from FT-818. 2/7
#hamradio #amsat #hamr Image
The comparison of NF & MDS of IC705, IC9700 and FT-818 assumes favourable IMD performance of the FT-818 with a 500 Hz filter. In the field this is rarely true and even less so with a passband of 3 or 2.7 kHz in SSB. 3/7
#hamradio #amsat #amateurradio #hamr Image
Read 8 tweets
When operating SAT-portable, the automatic Doppler correction of 2xFT-818 can be conveniently performed by a #RaspberryPi Zero W running #Gpredict and #Hamlib. Proven solid and reliable in DXing over the last 2 years. Read on for details 🧡

#amsat #hamradio #amateurradio #hamr
Doppler adjustment can be made manually but beyond calling CQ things get cumbersome. An automated tracking allows to quickly hop between different stations in the very limited time of the pass. For DX skeds this setup brings you spot on on the transponder frequency. 2/8 #amsat
RasPi connects to the WiFi hotspot of my iPhone enabling control and time sync. RTCZero backs up the system time. 2x CH340 USB-TTL converters connect the FT-818s to the Pi through Zero4U hub. 3/8
#amsat #hamradio #amateurradio #hamr #raspberrypi
Read 8 tweets
How portable can a #QO100 station be? Ultraportable, when running #FT8. No dish, <100 mW out (note the 3dB attenuator) and a 5000 mAh battery can power it for the whole day. 486 FT8 QSOs using this setup from JO89πŸ‡ΈπŸ‡ͺ so far. Few notes and thoughts
#amsat #hamradio #GHz_bands #hamr

This is neither the most light-weight nor elegant setup, yet it takes less backpack space than my LEO gear (2xFT-818 & Arrow). The size can be further cut down if an SDR is used. I don't do #SOTA or #POTA but have not heard of anyone adopting similar approach in their activations
1) 13dBi RHCP cavity-backed patch antenna on TX (FPV drone racing antenna will do)
2) Bare, modified single LNB on RX
3) Primitive bias tee and high-pass filter to enable GPSDO input and IF out from LNB via one cable
4) DXPatrol upconverter
5) Leo Bodnar GPSDO
6) Cheap SDR dongle
Read 4 tweets

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