Background:

• We tested 8 MHz.This was to the first hf test with the 430MHz  tx since the mar18 campaign.
  

What we did:

• The mesh was in the 8 MHz position
  
• we transmitted at 8.175 MHz rcp.
• 430 tx, single beam -> gr. za at za=1.06
  
• gr -> usrp
• ch -> echotek [4.5,8.5]]
• 12:00 start to bring up tx's
• tx5 pa cathode current 17Amps with only 40Kw output.  decided not to raise tx5 any more than 50KW. alfredo will look into it later.
• 12:36 50KW each tx output.
  
• 12:48 had to restart synth gui, was 100% cpu cycles
• 13:40  disabled all tx but tx1. Measured rise time pulse through tx
  
• siggen -> scope T (hiImp) ->synth driver
• coupler power tx 1 -> scope.
  
• Use rf on/off button to see the rise time.
• Tried hp siggen, but the button bounces. Ended up using hte srs output and button.
• 14:07; all tx back online. the modulation was accidentally left on the srs drive.
• 14:17 modulation of srs drive turned off
• 14:21 disable rf for 10 secs.
• 14:30 cycle mode 4sec on, 6 sec off. 407 KW.
• 14:39:09 cycle mode 2 on 8 off
• 14:43 stop auto toggle to get power level.. about 420 KW.
  
• 14:46 done
  

HF output power

Plots showing hf tx drive and output power (.ps) (.pdf)

• page 1:
• Top: hf rf coupler output vs hour of day
• Each color is a different tx.
• the low purple level is when tx5 was offline.
• The rapid changes in power are during cycle modes.
  
• middle: output power in KW
• bottom: synth drive amplitude (in dbf)
• page 2: hf drive power vs hf output power
• the output power (in KW) vs input drive power (in dbf) is plotted for each tx.
• values that lie below the trend, occur when an rf off occurs during a spectrum analyzer power average. cycle mode points have been removed.
  
• 
  

• dbf Drive for 50 KW output.. 8MHz

  tx	dbf drive
  1	-5
  2	-8
  3	-6
  4	-8
  5	-2
  6	-5

  
  

Generator power vs hf output.

    The data from the 3 running generators was used to measure how much generator power was needed to drive the 5 then 6 hf transmitters.

Generator output power vs hf output power (.ps) (.pdf)

• Top: generator output power vs time.
• middle: total rf output from 5 then 6  hf tx
• bottom: gen power vs hftx output power

TX risetime,delay

    The rise time, delay through tx1 was measured. The setup was:

•  siggen output (8.175 MHzMhz sine wave)->
• T on oscilloscope chan1 (hi impedance) ->
  
• phase synth inputs
• rf  Coupler tx 1 output -> control room front panel -> oscilloscope chan2 input (50 ohms)

    We set the oscilloscope to single trigger on the rising edge of channel one. We then used the rf on/off button on the srs siggen to turn the 8.175 MHz sine wave on.

The plots show the delay from siggen output to tx1 rf coupler ouput (.ps) (.pdf)

•  Top frame: delay measured using srs siggen.
• Black is the signal leaving the srs
• red is the tx1 rf coupler routed back to the control room.
• The difference is about 3 useconds.
• There may be a large fraction of a usecond in cable delay going from the control to the tx and coming back.
• Bottom frame:
• this used the hp siggen for the test.
• The rf on/off button on the hp siggen bounces. Looks like it takes up to 400 usecs to stabilize.
  

Plasma line movies

• Plasma line movies were made using the echotek and the usrp data. They had 10 sec integrations.
  
• A higher resolution movie was made with the usrp data. It blows up the freq and range showing the f-reqion line. The time resolution is still 10 seconds.
• Link to the movies
  

Summary:

• Tx5 was not raised about 50KW because of the high PA collector current.
• The delay from siggen out to rf coupler output (back at the control room is 3 usecs).
• we tried autotoggle  4on, 6 off, and 2 on , 8 off.
• There was a large enhanced plasma line after fof2 got above 8.175 MHz.
• A hires movie showed that the plasma line peak was being modified (smoke..) well before fof2 hit 8.175MHz.
  

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