David C. Hallam wrote:
Lothar,
I hate to be stubborn or dense, but where does the marker come from if the
"RF is dead on the tracking generator"?
I do have an operation and maintenance manual. I quote from the manual:
In Marker mode the scan ramp of the spectrum analyzer is stopped momentarily
at a point determined by the Model 844A Marker Position control. At the
point where the scan is stopped, a bright marker appears on the analyzer
display CRT. Simultaneously, the RF Output frequency from the tracking
generator is counted by the Model 8443A counter. If the Function switch is
set to Track Analyzer, the counter frequency indicates marker frequency,
independent of Spectrum Analyzer input signal frequency. If Function switch
is set to Restore Frequency, the counter indicates the Spectrum Analyzer
input signal frequency (as long as the marker is placed on the signal
response).
From the above statement it seems to me the generation of the marker on the
CRT display and the counting of the marker frequency are two independent
operations, i.e., you can generate a marker and still not be able to count
it.
Since I have demonstrated the counter portion of the 8443A is functional as
it will count an external signal from my signal generator and the RF output
the 8443A is functional since there is a marker on the CRT display, the
problem is in the counting of RF output frequency at the point where the
scan is stopped to generate the marker.
If I am still off base, HELP.
David
David,
You do seem to have been given a lot of advice on various topics, not all of which seem relevant to your problem. For example, the known 141 problem with bent D-sub connector brackets really only applies to the ones between the RF and IF sections. Usually due to the RF section being put on a flat surface, thus pushing on the connector. If the interconnect between the mainframe and TG is seated well at both ends, and locked in position, you should not have a problem there.
The marker is generated as you know by stopping the scan for a period depending on the resolution selected and simultaneously opening the counter gate. The marker will thus appear on the 141 display regardless of whether the TG is outputting anything. You can therefore have a marker and no output easily enough...
So your statemant:
the RF output (of)
the 8443A is functional since there is a marker on the CRT display
is not the case at all.
The easiest way to test for TG output is to select zero span on the SA and connect the TG output to the external counter input. With the TG output set above -20 dBm then you should now have a frequency reading identical to that you get normally. No output, no reading. You can also receive the TG output signal in a receiver tuned to the output frequency. Hard to avoid in fact with the full scan :^)
