Re: Type CA Channel B Gain Adj Problem

Don Black <donald_black@...>

I've checked bot the CA and 536 manuals and neither seem to have the usual waveforms that would indicate the signal level from the plugin to the mainframe. However in the TU2 test plugin (attached) it indicates 0.1 volt per division. You should be able to measure this at the mainframe and see if it gives the correct sensitivity. I suggest looking for more than one divisions at 0.1 volts per division. You'll need another scope for this, however any scope will do, you can check it against the calibrator if necessary.
Incidentally, are you relying on the calibrator signal for your measurements? It's always possible that's drifted and may be fooling you. You could measure an AC signal with a meter, calculate its peak to peak voltage (V RMS X 2√2) and see how that agrees with your cal signal.
Don Black.

On 30-Apr-13 12:07 PM, Cliff White wrote:

I just finished repairing a Type CA plugin. Everything seems to have calibrated just fine, with the exception of the channel B gain. It won't go low enough. For example, if I apply a .1 volt P-P signal, at .05 volts/div, the lowest the gain will adjust to is about 2.3 divs. It will go higher, but not any lower. Channel A adjusts perfectly. All other adjustments on both channels work fine. Does anyone have any ideas as to how I can fix this?

Cliff White, W5CNW

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