Owen Duffy wrote in
:

Dave Oldridge wrote in
:

...
I used to have an FT-221 tricked out with a hot front end. Solar
noise would run the S meter up to well over the S9 mark and you could
even see the galactic plane passing through the antenna pattern.
Needless to say, it heard well on terrestrial 2m SSB.

That is no mean feat!

I think ambient noise temperature at 144MHz for an antenna pointed at
cold sky is somewhere around 200K to 250K, when you add a pretty good
receiver at say 30K, you are talking 230K to 280K total system noise,
and the sun is probably around 800K with a low end 4 bay EME antenna
setup (Gain~22dBi), for a noise rise of 10*log((800+255)/255) or 16dB.

A single yagi of gain around 15dBi is much poorer, not only is the sun
noise reduced proportionately to the gain reduction, but the ambient
noise increases with higher gain in the side and back area of the
antenna, but it still should be possible to reliably 'see' the sun
with a very good receiver.

Ambient noise temperature for a beam at zero elevation here in
suburbia varies from 1000K to 6000K depending on the day and time...
so a very low temperature receiver is wasted for terrestrial contacts.

This was a VERY quiet location. The only VHF stuff around was a bit of
156mhz and 161mhz stuff on a tower about 5 miles away. I could JUST see
the big tower downtown that most of the FM broadcast stations used, but
it was about 12 miles away and partially obscured by trees and a hill.
But to the south and west was mostly ocean. VERY quiet VHF location. One
time I worked a guy in a plane flying from St. Johns, Newfoundland to
Montreal, on 146.49 simplex FM. He just had a handheld in the cockpit
window and we stayed in contact (from my suburban Halifax location) from
the time he reached cruising altitude (30-some thousand) until he began
his descent into Montreal. The distance at the end of the QSO was
approaching 800 miles.

I did not notice any particular propagation that day, this was just plain
simplex FM. Now I was running about 600 watts at my end of the pipe, but
I could hear his handheld just fine.

Near as I could measure it, the NF of the receiver after my mod was
1.2db. I had to resort to boiling and freezing water and a tiny dummy
load to measure it at all.


--
Dave Oldridge+
ICQ 1800667