47 GHz EME

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Working on a 38 GHz TWT amplifier to test and modify to 47 GHz, not sure if it will work out

I found a Hughes 8000 TWT amplifier for 38 GHz able to make 40 Watt output.

The first I needed for testing this was a dummy load and a coupler to be able to measure the power output.

AEROWAVE 22-2020S WR22 Square Flange (UG719/U) Medium Power Load, 15 Watts average, 1.1 VSWR

Then I started up the TWT for the first time to see if operation looks normal, after heating up waited for some time and then switched to on
All looked OK but there was no indication of helix current.
I tried to get some more documentation and when I got the documentation I found that it was quite possible that the helix current is too low for indication
Next step is try to get power output on 38 GHz and see if I can measure 47 GHz noise from the output of the TWT

TWT heating up  

TWT in operation

At the end of may 2020 I received my new pre-amp LNA to be placed in front of my transverter

Mny Tnx to all who made this LNA possible, it will be a very important improvement of my RX system

I will need to make some mechanical changes in my RX system to place the LNA in my RX chain

On 7 april I mounted the encoders for antenna readout and I measured moonnoise

Encoder for measuring Azimuth
Encoder for measuring Elevation
Using OE5JFL controller still need to confirm if It is useable

Later that day I did moon noise measurements

My first moon noise measurement was at 17 degrees elevation 0,45 dB

The best measurements I did was at 25 degrees elevation with 0,58 dB, see picture above


During the testing of my gearbox I already found that it was turning much too fast for reliable tracking.

I searched for possible solutions and decided to try if a pulse width modulated power supply for the electromotor would help

I found these small PWM motor controllers and decided to try if this would give me the solution

On 12 march I received this unit and first indication during a test looked promising.

As soon as weather permits I want to test this on the gearbox and hope that it will work out as hoped for.

At 3 march 2020 I made my first solar noise measurement using the 1.8 mtr dish and my home made feed

I had, as can be expected. to optimize the position of the feed for best performance

My first solar noise measurement resulted in a bit more than 2 dB.
After first adjustment I had around 5 dB
After the second adjustment I had 6.4 dB solar noise

This is already a nice result after only 20 minutes of trying.
It must be repeated but for this I need to improve the gearbox drive to turn much slower

I also measured hot earth cold sky resulting in about 0.8 dB


In December 2019 I started with a first setup for 47 GHz EME

Hearing from several stations working to be QRV with low power I joined in and see what would be possible

My first trial will be to test RX on 47 GHz and see if my antenna would be useable

I had a gearbox available for this but it needed an other electro motor because the original motor was turning
 the antenna at 360 degrees per second and this is way too fast

After removing the motor I build a replacement able to mechanical fit at to place of the old one

Old Electro motor, quite heavy with special coupling element to fit to the gearbox
Replacement motor with small gearbox

Replacement motor with special coupling element    

Gearbox ready for use with the 47 GHz
Precision 1.8 mtr prime focus dish
Dish mounted

1.8 mtr precision instruments dish f/d =0.4

After the modification of the gearbox the antenna was still turning much too fast.
 I am now trying to control rotation speed using puls width modulator in stead of a DC power supply.
I expect that in this way I should be able to reduce rotating speed to acceptable speed for following the moon

I also had to make a feed holder. I started with the original 11 GHz feed which was a feedhorn for 11 GHz with a round feed and several chokes.
I removed the 11 GHz feed part of it leaving the holding of the hub with a possibility to mount the 47 GHz feed

The original 11 GHz feed with hub feeding support

The modified feed hub ready for mounting the 47 GHz feed




To understand the possibilities to make a 2 way QSO using WSJT or CW I tried to make calculations based on station parameters which are possible by now

My first calculation trial is based on 1Watt output and a noise figure of 5 dB
At this moment I found that the atmospheric attenuation is still not very well known and I had to search for information on mm wave atmospheric attenuation but then based on EME propagation through the atmosphere, so aiming at the moon.

I found a nice presentation from UA3AVR
https://www.moonbouncers.org/Orebro2017/UA3AVR_Calibrations of mm-wave antennas and RX systems
using Moon radiation_Orebro2017.pdf

explaining atmospheric attenuation

Take a look at 47 GHz EME performance data from several stations