low pre-driver
Posted by
Robert Greenwalt-2 on
Jul 11, 2010; 9:35pm
URL: http://elecraft.85.s1.nabble.com/low-pre-driver-tp5280916.html
Hi,
When doing the 40-Meter Transmitter Alignment, I couldn't keep the output
power in th 1-2 watt range. Turning the power all the way up only got up to
.7 watts. I checked the output across the dumy load and it was practically
non-existent (.007Vrms) though key-down was noticeably different than
key-up.
I walked through the Transmitter signal tracing. Everything was within
tolerances until I got to the pre-driver output. I expected about .132Vrms
but got .07 Vrms.
I've checked all the components in the pre-driver section up through T1 (not
sure where pre-driver ends and driver begins) and they all have the right
markings. I verified T1 and reheated the connections.
On qth.net I only found references to high pre-driver issues. Suggestions?
Transmit mixer output: .016 Vrms
Buffer output: .216 Vrms
Bandpass filter output: .035 Vrms
TR switch output: .033 Vrms
Predriver output: .072 Vrms (expected .13 )
Robert, K6RJG
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