What we did:

• tx 4 broad band amp was replaced (after 12oct14, before start of this run).
• looking offline, alfredo said it was drifting around.
• Setup 5.125 Mhz, mesh 15 feet below reference.
• Look to see reverse power when mesh this low (8 mhz likes this position).
• saw large reverse power
  
• fwd pwr: 20-30 KW
• rvs pwr : 0 to 5.5
• move to 8.175 MHz. mesh 15 feet low.
• tx 4, 6  forward power computer readout was saturating (around 30KW).
• Also saw large 2nd harmonics.
• Measured drive level at broad band input.
• values linear to 0 dbfs drive.
• Found the hittite   6 port rf  switch for tx4,6 was saturating..
  
• So previous values tx 4,6 may be inaccurate.
• replaced 6 port rf switch
  
• calibrated the loss (with cables).
• tx1: 10.5 db
• tx2: 10.6 db
• tx3: 10.4 db
• tx4: 10.4 db
• tx5: 10.7 db
• tx6: 10.4 db
• Continued to use 10.5 db offset in anritsu spectrum analyzer.
• Saw tx 4 monitored output continuing to drift with time.
• put tx4 front panel broad band output on spectrum analyzer (with 10db pad).
• ran 0 span 600 secs, 100KHz rbw, .1 db/division.
• saw .03 db drift down in 600 secs. so broadband output is stable.
• measured gain of tx4 broad band:
• -1dbfs = +1.2 dbm at input to broadband.
• broadband meter read 140 Watts into 50 ohms.
• 140 watts=51.5 dbm. so 50 db gain.
  

Summary plots of the day (.ps) (.pdf)

• Page 1: morning, 5 MHz, mesh 15 ft low
  
• Page 2: morning, 8  Mhz. mesh 15 ft low
• tx3 (green trace) tripping on reverse power 10.95 with 50KW output.
• tx4,tx6 low.. probably because of bad 6port monitor switch.
• Page 3: afternoon, 8 MHz, mesh 15 ft low, new 6port switch installed.
• tx4 power level moving around.
  
• output of broadband looked stable (to .03 db over 10 minutes).
  
• tx3 trips (15.02 ) on rvs power with fwd pwr=70 KW.
  
• 14.25thunder, lightning, rain.
  

ToDo

• put monitor cable loss through switch in table.
• plot rvs/fwrPwr for 5 Mhz at 15 ft low.
  

Problems we found:

• Hittite 6 port rf switch  (ports tx4, tx6) were bad.
• replaced the switch
• showed large 2nd harmonic, saturation of fundamental.
• Forward power meter tx 6 reads higher than the value from the coupler by up to 30 KW.
• This could be a calibration problem.. But we also saw large harmonics on tx6 ...
• 5MHz will not work with mesh 15 feet low.
• Tx4 output power still drifting.
• saw arcing on . turning of tx 4 (or maybe it was tx3) caused it to go away.
  

processing: x101/161014/procday.pro

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