[DSP-10] 2nd EME2 Test, also nil, more questions.

[Courtney Duncan]

The improvements for today's moonrise:

- A better idea of where north is for rotator calibration, yesterday 
I was 20 degrees off (about half power right there).

- A boost from 6 W to 29 W.

- Looked for a "quieter" frequency, finally settled on 144.079300 
indicated, which is about 144.079150 correcting for my TCXO.

Other info:

- Local topography.  I'm not even sure I'm seeing the moon from here 
due to a nearby hillside to the east and lots of tree obscuration 
between here and there.  By the time the moon is high enough to see 
through all this, it's out of the vertical beamwidth of the antenna. 
Moonrises for the next few days are further south and later in the 
evening so that helps.  I also, potentially, have a better view 
towards moonsets.  I'll try one of those in a few days when it 
happens at a "reachable" hour.

Result:

Still nil, in fact the "central bin" spends most of its time < 0.000 
so it doesn't even report a Cntr Sig value.  I'm clearly not seeing 
any return, not even an ambiguous one.

New Questions:

- Are there gains or losses from operating near the horizon like 
this?  I'm trying to avoid antenna work, like fixing at some higher 
elevation than zero or, heaven forbid, an elevation rotator.

- What about the noise temperature?  This is a straight DSP-10 
without pre-amp.  I seem to remember Bob saying somewhere that it was 
about 600K.  Should I be using that for Te?  Would it help?  Or, 
conversely, should I not even consider attempting this without a 100K 
mast-mounted preamp?  (Seems like that could be 8 dB right there.)

- The frequency seems too quiet, actually.  The number in the lower 
right was around 5.75dB during the EME2 run and a subsequent noise 
measuring LTI run.  When I hooked the Brickette back to the antenna 
directly it's more like 7.75dB.  Is the amplifier passthrough or the 
cabling making me deaf?

In the "Oh Great" category:

- Well, in fact, recall all the trouble I was having getting my 
Brickette to show more than 5.0 - 5.5 watts on the Bird 10C?  Well, 
reconnecting with a different cable, I'm seeing 7.2 - 7.5.  Yep, 
that's 1.6 dB or so right there.  So never mind about the deaf thing. 
I have some cables to label "bad" now.

But let me just say that it is _so_ great to be using a radio where 
you can just do some built in measurement and figure out stuff like 
that!  When I originally did the "U15 Mixer Ground Modification" and 
was just able to diagnose and fix an important problem using 
measurements that the box would just take itself I was very impressed 
by what we've got to work with here.  What a great architecture!

73, Courtney, n5bf/6