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more channels to be inop.) Q206, 4207, & Q208 can cause loss of synth loop, no receive or no transmit. A quick check is to
look at the emitter votlage. It should be around .3 to .SV. If zero, transistor is open.
All pots can be intermrttent, especially if they are adjusted.
When a problem is suspected on this board. always check X enable, Y enable, and both hi-lo band switching tines. (1210 pin
14 & Q2l&collector) One of these is the inverse of the other.
TX drive output should be about 2.5MWCW.
L.O.Drive output should be about 5MWCW.
LO. tuning voltage should be adjustable from + 15 to + 21V.
Preselector tuning mbage should be adjustable from + 13 to ; 26'4.
L.O. tuning & preselectortuning voltage should be adjusted for optimum receiver, instead of absolute values of voltage. Monitor
detected output of IF Amp (RX video) and adjust L.O. 8. preselector tuning vottages for max. signal on all channels.
KN65 IFCVIDEO DECODER ( O D STYLE BOARD):
The old style IF board can be recognized by the number of IC's on the board. The old board has only (3) IC's. Of these 3,1402
& 1403 are no longer available. If one or both of these are bad, a new style IF must be used to replace the IF board.
W a k IF amp FETS can cause a loss of I or 2 DB in RX.
If IF has no "grass" (background noise), make sure decoder suppression 8 channel change are not ahvays high. A failure of
51.6 MHZ LO.causes no "grass". Grass level should be adjusted (WAGC pot) for .SW-P level on noisiest channel. Unit should
go into standby with no input signal. If not, grass level may be too high.
KN65 NEW STYLE IF BOARD, KN65A IF BOARD;
This has more 1C's than the old board and works with a higher video level than the old board. IF low "grass" level, C452, C453,
C454 & Q415 are good suspects. W a k IF AMP FETS can cause a loss of 1 or 2 DB of RX. Ifdecoder suppression or channel
change is always high, there will be no grass level or RX. A failure of 51.6 mhz L.O. will cause no grass or no RX.
RIT BOARDSOUD STATE DRIVER KN65, KN65A:
Make sure TX buffer is OK (on synth). C724, C719, & C713 can cause low power. Especially if the old style. (orange rubber
ring around base of part).Do not run SSD with back cover removed as Q702 will overheat.
C702, C704,C709, C7f 0,C716, C721 & C715 (de-coupling feed-through caps) can cause low power.
SSD output should be around BW, depending on the gain of the tubes. 5W may be enough. Q701 & Q702-class A stages 1ODB
gain. Q703 & Q704-pulsed stages 9DB gain. Doubler tube output should be 12W PA tube output should be 150W Final output
should be 100 W (KN65). 125W (KN65A)
Make sure L.V. modulator from PIS is OK
F37 BOARD-PRESELECTORKN65, KN65A:
CR705, CR707, CR708, CR709 & CR710
(matched varactor set) Can cause weak RX. Check for leaky feed-through caps while varactors are out.
CR706-mixer diode. Should have 100MVon TP703 all across band. The adjustment of synth 8 preselector will affect this
Duplexer diode failure can cause low power or TX freq problems.
Check for duplexer drive waveform.
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Check output of L.O. buffer on synthesizer board. C738 & C737 in L.0, quadruper can cause weak RX
VIDEO PROCESSOR KN65, KNGSA:
If C525 is old style (yellow cap) and is soft & spongy, replace. Unit will stay in standby if TP502 has less than 8 1VDC.Range
offset adjustment can cause thts.
TP520 is Hi in stby and Lo out of stby. Groundspeed problems are usually PIS faults.
If speed monostable output is at least .82 sec., and GIs is low, problem is speed fitter or speed buffer.