Posted on 11/04/2003 5:22:38 PM PST by Davea
==== Please don't get him started on Vince Foster.Far be it from me to yank _Jim's chain. =)
(Where have I seen that done before?)
I'm still of the impression that he's led a somewhat sheltered (focused on a certain set of subjects?) life insofar as technology (electronics in general, RF and 'systems') goes. Don't paint me 'black' for those opinions, this is just my honest appraisal given my experience in life and among a wide range of technical 'types' (persons) and technologies (hardware, software, embedded software, RF, Cellular system design and operation, Telemetery, GaAs Foundary, broadcast and RADAR, etc) ...
ROTFLMAO! You certainly know how to use big words. Here is an interesting but true story from a field test I was running.
At a remote location there was a requirement to run tests against a Cassegrain feed dish antenna. We set up a small two-foot dish antenna about 30 miles away on top of a local water tower. However, the large dish antenna we were testing could not see a signal from the water tower. Hmmm… Was it the pointing resolvers, or the feed, possibly even the receiver? We ran local BERs on the big dish and they all came out ok. So the next thing to do was to find out what the small dish was doing. There was no electricity there so we had a portable generator running at the base of the tower. Here is where we ran into a snag.
The spectrum analyzer only went up to 1.9GHz and the frequencies we were testing were up past 8GHz. The other problem was that we needed to test over a wide frequency range. Fortunately we had a Wiltron Scalar Network Analyzer and a mixer that was in the required bands. That evening we built a downconverter (using a metal box and a bag of parts I brought along) allowing us to calibrate and troubleshoot the small test antenna. We used a cal amp brick for an LO and used an xtal oscillator to stabilize it. To prevent spurious noise in the system thru the power supplies, we filtered the heck out of the power and isolated each DC input from the other. We placed a low pass filter on the output of the mixer and a 1dB pad between the two and an inline amp on the output. Since I did not have any circulators with us (sigh) I places a 3dB pad between the LO and the mixer with a 3dB pad on the input.
We now could “see” the signal with the spectrum analyzer we had with us. (Don’t ask why we did not have one in the band we were using.) It was a snafu not related to our test. BTW, all the connectors were SMA connectors except the input and output, which were N connectors. All the signal lines were semi-rigid coax.
We used the Wiltron to calibrate the output and create a spreadsheet on the laptop to determine the output over the entire required frequency range. Using this setup we ended up finding a bad N connector on the line from the main test oscillator to the small dish antenna. Changing this connector fixed the problem and we were able to test the large antenna.
That is just one of many problems I had to solve on the fly over the past 20 years. Remind me sometime to tell you about MILA radiating our spacecraft (locking up our receivers) thru the payload bay doors on the space shuttle during tests at the Cape and how we determined the problem and solution. How about the time an 11kW klystron gave us fits at a satellite control facility. Does designing and upgrading from Parametric Amplifiers for a front end of a 60-foot dish antenna to GaAs Fet LNAs count?
Calpernia and Dog Gone, thank you for your support! :-)
You're not. You can't concede a point, and you can't admit a mistake. But at least you've been consistent here for years.
Nobody here doubts that you're smart and have important comments to make. But you hurt your own credibility when you make the dumb attacks you're making on this thread.
I make this post knowing full well that you'll probably launch out on me. Lord knows, you can't take criticism.
Having lived and breathed them, having worked in those various technological segments and left my 'fingerprints' as proof in each and every one (plus several I'm sure I missed) - it entitles me.
Now, quit showing off ...
There are no points to concede ...
LIKE I wrote to Calpernia - let RA show up here and debate with the facts and supporting rhetoric - and NOT on 'perceived or projected reputation alone' ...
Unless you guys want to give me an EO to charge my time to - I'm a) outa here onto more important things and b) not about to debate senselessly in this fashion. Simply stated; get lives ...
Ah, one teensie little moment here. I know RadioAstronomer personally, and he has extensive hands-on experience working with these sorts of systems not only for the USAF and NASA, but several other agencies I'd best not mention. He has built satellites and radiotelescopes and currently works with them. His resume is quite impressive. Please don't disparage a fellow FReeper whose credentials are already proven and accepted.
RA, this little fishy isn't worth the effort. Forget him.
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