Adjusting the meters: procedure
adjusting the meters: measurements


Adjust power table template

Intro:

    Try to figure out the reverse power clipping levels:
What we know:

• Maximum forward power 100 Kw per TM
• maximum acceptable VSWR for band A : 1.75 to 2.25 (tx manual 1 page 520)
  
• test procedure to adjust reverse power trip should be set to 8.5Kw reverse power (txMan 2. p1367)
• For band A they say to use 5.83 Mhz (we used 5.125 Mhz)
• 
  

• Table of expected power values for given VSWR

  VSWR	RevPwr KW (for 100KW forward pwr)	50db coupler output (dbm)
  1.6	5.3	17.2
  1.75	7.4	18.7
  1.823	8.5	19.3
  2.0	11.1	20.5
  2.25	14.8	21.7

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Adjusting the  meters: procedure

    We altered the procedures for adjusting the meters (Txmanual p1249 6-6.3.1) since we are only using bands A &B , and we aren't going to use the rf feedback loop (we inject directly into the broadband amp). The sequence we used is:

• When removing, inserting cards 1,2 turn off the 120 v ride through breaker at hv control. back on when inserted.
  
• power meter forward
  
• 20dbm into hyb2, used 7.82 Mhz (band b) meter switch on forward, front panel rf sample to spectrum analyzer
• card 1a1 on extender (1st card).
  
• adjust R39 to meter reads 100 (sch p1-23 )
• linearity test. 20,17,14,11,10 dbm.. check meter.. verify on spectrum analyzer
• power meter reverse
• switch pwr meter position to reverse
• 20 dbm into AT16 , freq 7.82Mhz, select band B
• spectrum analyzer on reverse power sample (front panel)
  
• card 1a2 on extender (2nd card)
• adjust R104 to give 100 on meter
• check linearity:, 20,17,14,11,10 on meter and spectrum analyzer
• if not linear, you need to back off at5 (sch p1-14) until 20db is in the linear region.. then go back to r104 adjust
• reverse power trip
• band B: pwr meter select  reverse, sigGen  sitll in AT16, freq  7.82Mhz spectrum analzyer reverse power sample FP.
  
• adjust siggen to give 85 on meter
• card 2,
• trip comparator: U6 pins 2,3. use voltmeter
  
• pin 3 is the rf level that should generate a trip
• pin 2 is the reference we adjust
• move front panel pot reverse trip B till pin2 equals pin 3.. it was usually around 1 volt
• if you can't adjust the pot to pin 3:
• R102 rf level pot. Adjust this so that pin3 is around 1 volt. then go back to front panel B adjust
• Band A. siggen 5.83 Mhz into AT15, pwr meter reverse, spectrum analyzer on reverse power out sample (front panel) select band A
  
• 20 dbm should give 100..on meter
  
•  If not, there is no separate for bandA,B.. you could trouble should the gain difference between:
• AT15 ->at5,ar5,ar2 and AT16 going this same route
• linearity test 20,17,14,11,10
  
• set meter to 85, adjust card 2 front panel pot reverse trip A
  
• Look at pin2,3 again of U6
• adjust potA reverse trip so pin 2 equals pin 3. 
• Forward power BandA,B adjust atten
• BandA:20dbm , 5.83Mhz into AT9 (band a), select band A, spectrum analyzer on forward power sample
• adjust AT9 (from front.. remove narrow panel) to give 100
• linearity test 10,17,14,11,10 dbm. check meter and spectrum analzyer
• BandB: 20dbm, 7.82Mhz into AT10 . select bandB. spectrum analzyer as above
• adjust AT10 to give 100 on pwr meter
• linearity test: 20,17,14,11,10

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meter adjustments:

    The table below has the adjustments done.
green:  implies we're done with this tx
-- implies i didn't record any value, but the adjustment was done correctly

tx	date	band	fwd pwr siggen: 20,17,14,11,10 dbm		reverse power siggen,20,17,14,11,10			Notes
			meter	spcAnalyzer dbm	linear fullscale	trip level
						meter	siggen
tx1	150526	A	100,45,20,8,6	1.73,-1.20,-4.19,-7.16,-8.17	95,46,20,8,6 1.74,-1.18,-4.16,-7.14,-8.14	85	19.5
		B	100,45,20,9,6	1.76,-1.19,-4.16,-7.16,-8.15	100,46,20,8,6 1.87,-1.08,-4.05,-7.05,-8.05	87	19.5
tx2	150521	A	100,50,25,12,9	1.8,-1.12,-4.1,-7.08,-8.08	98,49,24,11,8 1.64,-1.25,-4.2,-7.2,-8.2	86	19.5	4
		B	100,50,24,12,9	-.92,-3.88,-6.85,-9.,88,-10.87	100,50,24,11,9 -.9,-3.9,-6.9,-9.9,-10.9	86	19.3
tx3	150518	A	98,-,-,-,8	2.0,-,-,-,-7.8	yes
		B	98,-,-,-,8	2.0,-,-,-,-7.8	yes	85	18.6
tx4	150519	A	100, was linear, no record	-,-,-,-,-	yes
		B	100,was linear, norecord		yes
tx5	150522	A	104,50,24,11,9	1.8,-1.11,-4.08,-7.09,-8.08	95,46,22,11,8 1.25,-1.66,-4.63,-7.61,-8.60	85	19.5	2
		B	100,48,23,11,9	-1.1,-4.01,-6.99,-10.,-10.99	104,50,24,12,9 -1.26,-4.20,-7.13,-10.11,-11.12	87	19.3
tx6	150519	A	100,45,-,-,7	-,-,-,-,-	95,-,-,-,- .. linear but no record	80	-	1.
		B	100,45,-,-,6	-,-,-,-,-	100,45,-,-,8		-

• 1. AT9 resistor bad. replaced with 3 resistors from at17,at19,at20.
  
• 2. power meter was sticking at 20kw.alfredo fixed it than reinstalled. For reverse power, A,B was  a bit off so we split the difference.
• 3. 150520: +15 volts U7 card 2 has 3 volt pkTopk ripple. need to fix supply
• 4: 150520  +26volt supply ps1 .. no voltage, no band select.
• on 150521 the +26volt supply was working again so we did the calibration.
  

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