Re: 7A16A high frequency compensation.


unclebanjoman
 

Ozan:
yes, I'm always using a x10 50 ohm attenuator and a 50 ohm feed-thru termination at the BNC plugin. The same pieces I use with a 7A16 (not A) without problem.
Using a cable 50 cm more long, the width of the first step increases a little. Remember that I measure the waveform after R10. Measuring directly at the BNC pin of the plugin, the waveform changes, in the sense that the middle step is a the 80% of the final value, instead of the former 50%.

Raymond:
I did not check the continuity between the input BNC and R132. The form of the signal gives me strong suspicions that there may be something anomalous in the signal path even if, being the input selector au 10, V / div, all the "A" contacts should be closed ... giving a direct path from the BNC to the R130/R132 junction.
I'll check the continuity with a DVOM tomorrow.
And yes, I'm from Italy.
I already tried to reverse the Q150 since it's symmetrical. No changes whatsoever.
Unfortunately I only have the 500 ohm probe original from Philips, given together with the 3340 having type N connectors. I have a good 7A19 but not a suitable probe (I'm searching one at a reasonable price).
I've already tried to swap U350 and U450 some days ago, with no results, so I doubt it's the culprit.
I will try to unplug U350 and measuring the signal at pin 14. At this point we might as well try all the possibilities ...
I have tried also a 155-0078-01 pulled out from a 465 I use for parts, still with no noticeable results.

Max

Max

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