[1000mp] Key clicks meaurements

[Rick Stealey]

I just thought I would pass along to the group the status of some tests I 
have been making on key clicks with my original model 1000MP, unmodified.

I use an HP 141 series spectrum analyzer with settings similar to what ARRL 
used.  That is, a 30 Hz bandwidth, very slow sweep speed across the signal 
from the 1000MP which is keyed with a string of very fast dots from an elec. 
keyer.  ARRL did the same with a better analyzer, and then presented data 
"normalized to a 500 Hz bandwidth."  This means they added approximately 12 
db to the readings (10LOG(500/30) in my case).  With this setup I can see 
down to 85 db below the carrier.  My results are within about 2 db of what 
ARRL got so I feel quite confident I am doing this right.

Here's some interesting observations of what I saw in my 30 Hz window:
- At 0.5 KHz from the carrier sideband level (due to keying) is down 42 db.
- At 2.5 KHz I can see almost no increase in the noise whether the rig is 
keyed or not

So then I got out my Icom 746.
- at 0.5 KHz from the carrier the sidebands are down 50 db (8 db better than 
the 1000MP)
- at 1 KHz the Icom is 5 db better

Now the fun begins.  I wondered what an old xtal controlled DX60 would look 
like.  It should be better, right?  Failed the test!  It has such high 
levels of 60 HZ (or is it 120 Hz?) that I couldn't measure!!  Maybe in a day 
or so I will get it fixed.  Then the next rig to try was a Drake T4X.  It 
was blowing fuses and I have been trouble shooting it all day long but now 
got it going, so maybe tomorrow I can try it.

Then if I can get enough attenuators I may try some subjective tests using a 
receiver, and see if I can hear the differences in the rigs.
Maybe the 75S3 would be a good one to use, with its 200 cy cw filter, or the 
R4C.

Rick  K2XT



_________________________________________________________________
Chat with friends online, try MSN Messenger: http://messenger.msn.com