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Old 19th May 2021, 8:07 am   #1
LA9CHA Thorvald
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Default Heathkit OS-2 Oscilloscope

Hello, is there anybody who know a way to increase the vertical sensitivity of this scope. Perhaps a DIY amplifier, transistor or valve ciricuit. Ideas are most welcome!
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Old 19th May 2021, 9:05 am   #2
ronbryan
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Default Re: Heathkit nOS-2 Oscilloscope

You could look at what Telequipment did for their C2 plug-in for the D43 scope. I've attached a snip of the circuit. The full C2 manual is available on Jonz Valve Page if you want further information.

It is a FET and transistor amplifier. DC drift should not be a problem as I expect the Heathkit C2 is AC coupled only. The transistors are supplied from the 235V HT via a dropper and zener.

Ron
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Old 19th May 2021, 10:08 am   #3
LA9CHA Thorvald
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Default Re: Heathkit nOS-2 Oscilloscope

Hello Ron an many thanks for answer. This looks as just what I need and was looking for. I shall to make it up on a bread-bord and try!
Tks again and best regards: Thorvald
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Old 19th May 2021, 7:57 pm   #4
Bazz4CQJ
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Default Re: Heathkit nOS-2 Oscilloscope

Wasn't the last gasp of valve oscilloscopes the use of Nuvistors; I'm sure I've seen some circuits using them as pre-amps. I've had some difficult experiences trying to make hybrid circuits work, though perhaps that's just me.

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Old 20th May 2021, 6:19 pm   #5
LA9CHA Thorvald
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Default Re: Heathkit nOS-2 Oscilloscope

Hello again Ron. I have tried several times to get the manual fro Johnz valve page, but every time I am redirected to another page where I am asked to fill in "Manufactor". What doe I doe wrong?
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Old 20th May 2021, 9:04 pm   #6
ronbryan
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Default Re: Heathkit nOS-2 Oscilloscope

Thorvald

The following address yields the Telequipment C2 plugin manual directly.

https://w140.com/telequipment/module_c2.pdf

Ron

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Old 21st May 2021, 10:45 am   #7
LA9CHA Thorvald
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Default Re: Heathkit OS-2 Oscilloscope

Hi Ron, this time I got it all! I owe you one!! tanks a lot. Thorvald
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Old 21st May 2021, 2:53 pm   #8
orbanp1
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Default Re: Heathkit OS-2 Oscilloscope

Hi Thorvald,

Here is an "interpretation" of the C2 pre-amp.
The OS-2 has a bandwidth from 2Hz to 3MHz.
The pre-amp has a gain of 40dB (100) and a bandwidth from 1Hz - 3.4MHz.
It starts clipping above 20mV RMS input.
You need to provide the 12V supply, the current draw is about 5mA.
The simplest (and safest) would be using a small extra transformer for it.

Regards, Peter
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