K1 transmitter dead

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K1 transmitter dead

Cherie and Lynn Hammond
My K1 died after several years of fine service. Very little of any RF
power output. Although the display suggests full power is there, the
external wattmeter shows a watt or less. Checked the wattmeter with the
K2 and it is working correctly.

RF probe measurements suggest that the problem is at Q5, since the OSC
test point measures .02   volts (in range) and the PRE test point
measures .033 volts (just below range) . However the ATTN point (TX
attenuator) shows .01 volts (should be .02 volts) and the MIX point
shows .01 volts (should be .1 volt) . These seem to suggest that either
Q5 or D18 has expired.  However my DC voltage chart gives no values for
Q5. No apparent bad joints or shorts in that area.

Should I just replace Q5 and D18 or what? Seems odd that they would fail
after several years. Any ideas appreciated.

73
Lynn KL7IKV


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