"Owen Duffy" wrote in message
...
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.

Owen

Owen

I would like to see what mods are made to the 221 to do that and also what
kind of antenna system. I have a 221 I am using with a gasfet preamp in
the shack that should be less than 1 db of noise fugure and about 20 db of
gain. The antenna is a klm 22c and 75 feet of 9913 type of coax. I can
just see some sun noise with the antenna aimed at the sun. It sure does not
deflect the smeter several sunits. The antenna is on an azel mount. I am
sure the system is working as I compaired it to an Icom 706 and another
antenna that is mounted on a tower and I am getting about the differance in
signal levels I would expect at the horizon.