KT-88 Data sheet question.

[rlaury]

Hi Group:
I've been looking at data sheets for a long time. For the most part I can figure out what I need to know. But on the Genalex, Gold Line and other data sheets
there are two parameters that specifies the Voltage for the Plate and Screen, Va, g2(b) and Va, g2(o). My question is what is the (b) and (o) indicate??
I've looked high and low for and explanation.

http://www.westernelectric.com/produ...spec_sheet.pdf

Any ideas

Thanks
RonL

[DF96]

No idea. (0) (i.e. zero) may mean no signal, but I don't know what (o) and (b) mean. Have you tried looking for the original GEC data sheet, not some modern rehash of it? The people who write modern valve data sheets often don't know what they are doing, as they were brought up on chips and transistors. Hence they make mistakes.

[rlaury]

Thanks for the reply. It seems to be on all of them:

http://www.datasheetcatalog.org/data...3/633155_1.pdf

[DF96]

OK, wild guess coming up: Va(b) could mean HT supply voltage, Va(0) means voltage at anode with no signal present (after DC drop through output transformer primary resistance). This doesn't quite seem to fit the figures they give, so don't take it as gospel. As I said, a wild guess.

[SY]

I checked a couple of the figures and your interpretation of the o is consistent- values at no signal.

[Rod Coleman]

Originally Posted by DF96

OK, wild guess coming up: Va(b) could mean HT supply voltage, Va(0) means voltage at anode with no signal present (after DC drop through output transformer primary resistance). This doesn't quite seem to fit the figures they give, so don't take it as gospel. As I said, a wild guess.

Wild guess can be confirmed as nearly correct!


Here is a clip from the 1952 edition of

Markus & Otte "Data and Circuits of Radio Receiver and Amplifier Valves" Book IIIa

A text well worth having, for many such instances of nearly-forgotten knowledge.

[richwalters]

Originally Posted by rlaury

Hi Group:
I've been looking at data sheets for a long time. For the most part I can figure out what I need to know. But on the Genalex, Gold Line and other data sheets
there are two parameters that specifies the Voltage for the Plate and Screen, Va, g2(b) and Va, g2(o). My question is what is the (b) and (o) indicate??
I've looked high and low for and explanation.

http://www.westernelectric.com/produ...spec_sheet.pdf

Any ideas

Thanks
RonL

Va(b) was an old term for battery voltage....now anode supply volts;

Ia+g2(o) = Combined anode and screen current at Zero output.
Va (o) = Anode volts at Zero output.
Ia+g2(max sig) = Combined anode and screen current at MAx output.

richy