Sunday, December 8, 2019

Radio Astronomy 8.4 GHz, part 1: building antenna

It was my childhood dream, EME and radio astronomy. I took long years and now I do have room and rest parts but missing time :) This winter (2019) I have decided to do something. On the wine with my friend Lubos OK2BEN we have started to speak about mechanical parts. He sent me full mechanical drawings after a few weeks :) What a service. Also with the full list of parts so I just could order it and start...

The mechanical system is based on nice HW by Marek OK2DL

A few years ago we got nice 4m dish from NEC. It has got f/b = 0,25. It is not very usable for EME. I have decided to learn more about mechanical systems and good RX from the space. This is great possibility.

So I bought welding machine and started learning :) There is a lot of to improve and learn...

Thanks to my girlfriend Lucka for help :)

Franta OK1CA visited me one day and we spoke about satellites, EME and also 8.4 GHz. He offered me his septum feed design. I bought all parts for two pieces and found one Sunday. Result was one feed which I sent to Franta for tunning. Thanks a lot Franto! He allowed me to publish his designe: HERE you can download it.

I found small piece of CuAg sheet and started.

And there are results for port isolation and S11:

 Photos from Franta: Kumar for dish

Tuesday, November 26, 2019


We had a lot of work before contest on RX antennas, Top Band vertical etc. Finaly a few hours before the contest we were ready. Just 20min before contest start we lost tubes in OM-4000 (second time)...

We now do have ready 9 beverage antennas including 2 wire Bi-Directional one and 2 el end-fire to NA. Adding RX CMCC (common-mode current choke) helped and we feel lower noise from beverages. All HW is from :)

 Pavel OK1MU as OK6W SOSB 80m HP
 160m Top Band vertical tunning box
Beverages :)

3830 notes from PAvel OK6W:
Fantastic contest and great fun for 42 hours, which I spent on the band. For the last 3 weeks we have been working very hard on QTH to prepare all equipment for 160/80m, which proved to be crucial during the contest.

Btw, In 2016 I was also on SOSB80m HP, but the conditions for the directionforf the USA were poor, and excellent for JA. This year it was quite opposite. I did great number 640 x NA (previously only 300 NA) and 138 x JA (previously 184 JA). Amazing was the number of BY, which is 22 in the log and also 7 x VK on 80m is good from OK land.

Used IC-7800, OM Power and Sloping dipoles with 4SQ hybrid, antennas multibeaming and Rx switching. Good improvement on RX antennas with additionals CMCC (common-mode current chokes) and 2el end-fire beverage to NA. All parts from . For RX used 9 QTF BVRGs, totally over 2400 meters... 
My greatest thanks go to our technical guru Jan OK2ZAW, for complete technical setup and eating service during the contest!

Anyway, it was a beautiful contest that I will remember for a long time. I really appreciate that we managed to break the 15 years old country record held by a nice friend and a great contestman Jirka, OK2RZ!

Thanks a looooot for everybody who calling me, without you, the CQWW would not be what it was !

Pavel OK1MU/OK6W

Tuesday, October 1, 2019

CQ WW RTTY as OL9A SOSB20 again

RTTY again! I missed it a lot. I run last CQ WW RTTY from OL7M Contest QTH in 2016 on 80m.
Than we were guests at A44A - great experience! So it was time to try our almost full setup for 20m. We are now missing one TOP yagi (38m) fixed to NA and rotary 5el in 31m. Mainly the TOP NA antenna is missing a lot! 

We made some rest work around wood on Friday and all setup was set up really fast. All worked great. We had also luck, because we lost electricity on Monday thanks to the strong wind.

And how about the contest? I was thinking about one milion of points but Aurora (K = 27) said NO :)
There are results from my last participation on 20m in 2015:

I made 712 NA stations (K + VE), 7 KH6, 5 KL7... And 263 JA stations.
This year:
I made 400 NA stations (K + VE), 0 KH6, 1 KL7... And 138 JA stations.

Compare to 2015 here.

During the first day I had only ONE QSO to California :)

Anyway one highlight from 3830 of W6QU / W8QZA with QRP! :
I had no QSOs in this contest that were outstanding, all were regular contest
Qs. I did have a lot of trouble getting into Europe and it was late Sunday AM
before OL9A finally came back to my calls. That was the event of the contest! I
gradually picked up 3 more Euros for a total of 4. Last year I had 17. 

Second day was better to NA, also worked 12 CA (49 CA in 2015) and found some more mults.
I used my IC-7800 and the second RX for searchong the mults. It was really nice, I found about 5 mults, when I stopped somewhere, than looked to decoder after some time and multiplier was there :)

Lets do something before contest :)
 Part of your antennas