[Moon-Net] Q65 120a QSO's on 2 meter EME.

Earl Shaffer wb9uwa at gmail.com
Sat Apr 17 17:33:11 CEST 2021


Hi All

In keeping with the requirement  of using WSJTx rc4 I am reporting recent
activity using that software.

This is a timeline of my initial QSO with VK2XN.
I think degradation was something like -5db and 600k noise.
My noise level was about 4 to 5 db above a dummy load.

VK2XN  17EL 300 no elevation.

Q65 120a

17Apr 00:47 CQ CQ CQ 1ST 144.144 Q65 120A ====== {WB9UWA/4XP12/1K
17Apr 01:06 moon visible @ 0104Z and you magically appear on my waterfall -
VK2XN
17Apr  0118 -27  2.7 1493 :  WB9UWA VK2XN QF59  q0
17Apr  0130 -35  2.7 1502 :  WB9UWA VK2XN R-35  q3
17Apr  0132 -27  2.8 1155 :  VK2XN WB9UWA RR73  q3       Thanks Earl..
17Apr  0134 -28  2.5 1503 :  WB9UWA VK2XN 73    q3
17Apr  -24 your best deepest decode -35 ====== {VK2XN Wayne

You can see that between 0118 and 0130 there was an extended fade.
We noted at times that the fade was same at both ends.

Initial. Many times the signal was present on the waterfall but no decode.
I could have seen short hand signals in this case shortening up the QSO.
There were many peaks and fades over this period of time as is usual.
Of course I am used to adaptive polarization and I have only vertical or
horizontal RX with WSJTx rc4 right now. I was monitoring the waterfall from
Map65 and comparing it to the waterfall on WSJTx. Any time I saw a better
signal on Map65, I would change RX polarity. That works pretty well for me.
One thing I like about 2 meter EME is that there are many tropo stations
that I can work off the moon. With proper timing I think this QSO could be
done on JT65b where the short hand signals would be decoded by eye using
the waterfall during the first fade. I have decoded JT65b signals at -27db
before on both Map65 and WSJTx. Wayne noted that I was much stronger
(speaker copy) after the QSO. Perhaps he had better ground gain at this
time.

JA5EEU   4RP 500
I worked JA5EEU after this QSO and he was a bit stronger. On another
occasion I easily made a quick JT65b QSO with him. This QSO lasted about 20
minutes and as noted in the previous QSO there were many fades and peaks
over that period of time.
There were times that the signal was strong enough that it should have
decoded but it was not.
JA5EEU may have had more frequency drift than VK2XN.  JA5EEU also reported
early on that he saw strong but undecoded signals from me.
These two Q65 120a QSO's reminded me a lot of the old 1 hour CW skeds where
you have to ride several peaks and valleys to piece together calls and
reports.

UA9YJM 4X10H 300
UA9YJM Called CQ after this and I answered his CQ. We had a fast JT65b QSO
and his best was -20db which is the strongest I have ever seen him.
Generally my noise level was 6db above a dummy load and my moon elevation
was 28 degrees by this time.  Any 300 watt station is a great catch for me.

I really, really wish I could use short hand signals for Q65. At that point
I think Q65 120a would make a good DX mode for working very small (initial)
stations. There were many times I would have seen the short cut signal on
the waterfall but instead was presented with a no decode. This is true
especially considering that the sync tone of Q65 is considerably weaker
than for a JT65b sync tone. I can see that weak QSO's on Q65 300a could
easily go on for over an hour.  Signal fades are often so severe that even
more sensitive modes do not make up the difference. Even after all these
years, JT65b remains a great DX and contest digital mode. I suspect that
Urban noise makes for more QSB than what might be expected by those lucky
few that live in a quiet neighborhood. Very strong bursts of noise may take
out a digital signal while a simple pattern may still be decoded by eye on
a waterfall.  In my mind it is much like digital TV. In the days of analog
TV you may see noise bursts or tears in the image, but never lose the
picture. Digital TV is all or nothing. When people ask me about what
antenna to use for digital TV, I tell them it is easy to pick up digital TV
but hard to do it reliably.

-- 
Earl Shaffer,  WB9UWA

My EME array photos
https://www.dropbox.com/sh/bbn2ktonko8e3az/AACHBBOhf6Djk5Pf2c86Br5ja
Detailed array photos
http://www.gm4jjj.co.uk/WB9UWA/
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