John,
The base of Q8 is very low - it should be about the same as Q7. Check the
components of the base circuit for proper values and proper soldering. Use
the schematic to identify the components.
Your DMM is showing the forward voltage of the diodes.
73,
Don W3FPR
-----Original Message-----
I rechecked Q5 base and collector values and they are as I stated.
W1 remains at 40V on xmit.
I do not have a wattmeter.
Now, I am going down the DC voltage tables for the RF board. So far,
D1 thru Q2 are normal.
I am confused by the directions. Directions are for receive unless
specified, zero AF, mid set RF gain. If, as you instruct, I turn
power down to zero to read DC, then Q5 collector is zero, as is B, C
and E of Q6. Am I wrong, or is this to be expected when power is at
zero? If getting DC readings on transmit is fruitful, based on what
you told me, how do I proceed to get accurate TRANSMIT DC readings?
Here are "Transmit, Mixer, Buffer, Band-Pass Filter, T-R Switch
readings from page 14 of troubleshooting.
(Power set at 2)
RF readings:
2. Xmit Mixer Output Expected .016 Vrms Actual .03
3. Buffer Output: Expected .2 Actual
.211
4. Band-Pass Filter Output .03
.35
5. T-R Switch Output .029
.011
Pre-driver, Driver and PA
1. Pre-Driver Output Expected .120 Actual .11
2. Driver Output .026
.16
3. Driver Output 1.8
3.6
4. PA Input Q7 .38
.82
5, PA Input Q8 .38
.04
6. RF Detector Input 2
.7
7. PA Transistor Tests
Q7&Q8
positive lead on base: Expected at emitter and collector:
.6
Actual .537
negative lead on base: Expected at emitter 1.3 Actual
.511
Expected at collector
>3 Actual "OL"
My PA voltage is too high and Detector voltage is too low: indicating
defective PA transistor(s). Does the above test eliminate them as
the culprit?
Note: On my DMM, diode test shows "v" not "k"...the values seem to
match but is this voltage or resistance?
John
AB8WH
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