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{{Monolithic IC | |||
|Manufacturer=Tektronix | |||
|Model=M077A | |||
|Part_nos=155-0059-00 | |||
|Description=HF amplifier | |||
|Used_in=7834;7844;7854;7904;R7903;R7912;7912AD | |||
|Designers=Thor Hallen | |||
}}, designed by [[Thor Hallen]]. The Tek custom chip catalog calls it a "Gain Trim Amplifier". | |||
It comes in a 12 lead TO-8 package and is used in the vertical amplifiers of the 400 MHz and 500 MHz scopes from the [[7000 series scopes|7000 series]]. | It comes in a 12 lead TO-8 package and is used in the vertical amplifiers of the 400 MHz and 500 MHz scopes from the [[7000 series scopes|7000 series]]. | ||
The final vertical gain adjustment is after this amplifier and it typically leads into either a [[155-0064-00]] or [[155-0065-00]] | The final vertical gain adjustment is after this amplifier and it typically leads into either a [[155-0064-00]] or [[155-0065-00]] output amplifier which drives the vertical deflection plates of the CRT. | ||
output amplifier which drives the vertical deflection plates of the CRT. | |||
==Repair issues== | ==Repair issues== | ||
Note that this IC can fail by becoming non-linear. It will continue to amplify but | Note that this IC can fail by becoming non-linear. It will continue to amplify but will show non-linear gain and clipping when using a step calibrator. | ||
will show non-linear gain and clipping when using a step calibrator. | |||
According to [http://hakanh.com/dl/docs/kitinstructions/050-0650-00.pdf Modification 050-0650-00, Vertical HF Amplifier Replacement], the emitter resistors need to be selected according to a code printed on the device. | According to [http://hakanh.com/dl/docs/kitinstructions/050-0650-00.pdf Modification 050-0650-00, Vertical HF Amplifier Replacement], the emitter resistors need to be selected according to a code printed on the device. |