Heathkit OS-2 Oscilloscope - UK Vintage Radio Repair and Restoration Discussion Forum

LA9CHA Thorvald · 19th May 2021, 9:07 am

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!

ronbryan · 19th May 2021, 10:05 am

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

LA9CHA Thorvald · 19th May 2021, 11:08 am

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

Bazz4CQJ · 19th May 2021, 8:57 pm

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.

B

LA9CHA Thorvald · 20th May 2021, 7:19 pm

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?

ronbryan · 20th May 2021, 10:04 pm

Thorvald

The following address yields the Telequipment C2 plugin manual directly.

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

Ron

LA9CHA Thorvald · 21st May 2021, 11:45 am

Hi Ron, this time I got it all! I owe you one!! tanks a lot. Thorvald

orbanp1 · 21st May 2021, 3:53 pm

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

19th May 2021, 9:07 am	#1
LA9CHA Thorvald Pentode Join Date: Dec 2019 Location: Egersund, Norway Posts: 208	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!

19th May 2021, 10:05 am	#2
ronbryan Octode Join Date: Jan 2003 Location: Guildford, Surrey, UK. Posts: 1,960	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 Attached Thumbnails

19th May 2021, 11:08 am	#3
LA9CHA Thorvald Pentode Join Date: Dec 2019 Location: Egersund, Norway Posts: 208	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

19th May 2021, 8:57 pm	#4
Bazz4CQJ Dekatron Join Date: Apr 2009 Location: Oxfordshire, UK. Posts: 4,935	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. B __________________ Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch.

20th May 2021, 7:19 pm	#5
LA9CHA Thorvald Pentode Join Date: Dec 2019 Location: Egersund, Norway Posts: 208	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?

20th May 2021, 10:04 pm	#6
ronbryan Octode Join Date: Jan 2003 Location: Guildford, Surrey, UK. Posts: 1,960	Re: Heathkit nOS-2 Oscilloscope Thorvald The following address yields the Telequipment C2 plugin manual directly. https://w140.com/telequipment/module_c2.pdf Ron Last edited by ronbryan; 20th May 2021 at 10:24 pm.

21st May 2021, 11:45 am	#7
LA9CHA Thorvald Pentode Join Date: Dec 2019 Location: Egersund, Norway Posts: 208	Re: Heathkit OS-2 Oscilloscope Hi Ron, this time I got it all! I owe you one!! tanks a lot. Thorvald

21st May 2021, 3:53 pm	#8
orbanp1 Heptode Join Date: Nov 2009 Location: London, Ontario, Canada Posts: 675	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 Attached Thumbnails Last edited by orbanp1; 21st May 2021 at 3:59 pm.