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EEVblog #693 - AVO Transistor Analyser Teardown
Posted by
EEVblog
on 17 Dec, 2014 03:11
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Dave tears down a 1962 vintage AVO Transistor Analyser.
The auction score video:
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#1 Reply
Posted by
SeanB
on 17 Dec, 2014 04:24
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I have the baby brother of that one, it fits in the box in the middle.
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#2 Reply
Posted by
ratdude747
on 17 Dec, 2014 06:50
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A note: The two connectors to the battery board ARE latched... if you look, there are two barrel spacers bolted to the inside of the compartment that hold the plug in the socket.
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#3 Reply
Posted by
Lightages
on 17 Dec, 2014 07:05
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My first thought when seeing those flatish devices marked 1R is that they were diodes. I would never have thought them to be capacitors. Are you sure Dave?
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#4 Reply
Posted by
digital
on 17 Dec, 2014 08:22
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Dave please replace that condenser and do a video of the tester working I am sure a lot of others would enjoy it.Regards
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#5 Reply
Posted by
G7PSK
on 17 Dec, 2014 09:05
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Hi Dave, To make AA batteries fit you need a stack of coins to fit under the spring and on top of the cell.
I have a whole load of 1950's to early 1970's transistors I can send you to test all brand new and unused.
Your unit could well have been unused as the military have the habit of storing equipment just in case they have a war and then after forty years or so realise that it is out of date, I have had a few bits of kit unused ex military.
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#6 Reply
Posted by
German_EE
on 17 Dec, 2014 09:29
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Dave, I am almost certain that your analyser is ex-military. The secret is the brass plate which shows a small arrow pointing upwards, this was the symbol for the War Department in the UK (now called the Ministry of Defence). Now that we know you are dealing with a military device it explains the build quality including the laced wiring, the chunky switches and the rubber seals.
I was Sagan's age when this unit was manufactured
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#7 Reply
Posted by
jipihorn
on 17 Dec, 2014 10:08
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"Love a good set of balls"
Brilliant.
J.
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#8 Reply
Posted by
nathanpc
on 17 Dec, 2014 10:45
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I would love to see a video of you replacing those old capacitors condensers and playing around with it analyzing some transistors.
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#9 Reply
Posted by
fcb
on 17 Dec, 2014 11:33
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I think you'll find all AVO stuff of that vintage is equally well built.
What is slightly puzzling (mainly because I don't know the history of the UK<>ADF agreements) is why it has the UK MOD plaque on it.
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#10 Reply
Posted by
JackOfVA
on 17 Dec, 2014 12:25
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Battery holders appear to be based on 7 or 9 pin vacuum tube sockets and shields.
Yes, please see if you can make it work - would make a great 2nd part video.
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#11 Reply
Posted by
R_Gtx
on 17 Dec, 2014 13:08
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I hope Dave doesn't just swap the leaky dustbins with modern replacements, but correctly, as with all vintage equipment, re-stuffs the original cans.
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#12 Reply
Posted by
c4757p
on 17 Dec, 2014 13:20
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Ew, god, restuff the cans? I hate it when people do that. This is a tool, and a beautiful piece of engineering, not some wanky painting or something - its beauty comes from the practical, functional design, not the specific shape and size of the capacitors... Hiding nice, modern parts inside crusty old ones seems to me a bit of an insult to the spirit of the engineering work that went into building this in the first place. Do you think, given a choice between a modern capacitor from 2014 and one of the caps that were available in the 1960s, the original engineers would have chosen the latter?
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#13 Reply
Posted by
Macbeth
on 17 Dec, 2014 13:25
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My first thought when seeing those flatish devices marked 1R is that they were diodes. I would never have thought them to be capacitors. Are you sure Dave?
I instantly thought this too...
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Imo a C cell battery would fit perfecly in those battery cans .
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#15 Reply
Posted by
c4757p
on 17 Dec, 2014 13:33
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Imo a C cell battery would fit perfecly in those battery cans .
Do you think so? They looked just a bit too small to me - but then again, I don't handle C cells much.
My first thought when seeing those flatish devices marked 1R is that they were diodes. I would never have thought them to be capacitors. Are you sure Dave?
I instantly thought this too...
Yup, those look like diodes to me.
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#16 Reply
Posted by
Macbeth
on 17 Dec, 2014 13:34
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Dave, I am almost certain that your analyser is ex-military. The secret is the brass plate which shows a small arrow pointing upwards, this was the symbol for the War Department in the UK (now called the Ministry of Defence). Now that we know you are dealing with a military device it explains the build quality including the laced wiring, the chunky switches and the rubber seals.
I was Sagan's age when this unit was manufactured
Definitely Ministry of Defence. I also wonder about that "MOD" sticker Dave thinks is for recording modifications. I think it is for some other M.O.D. purposes myself.
The arrow you speak of is also printed on the clockface of UK military watches, ration packs, belt buckles, etc, etc.
I have to hand it to AVO, they made fantastic old school meters like the AVO-8 in their bakelite cases with hand wound resistors, and hand painted and calibrated dials with parallax mirror. I would say a whole magnitude in quality above an old Simpson.
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#17 Reply
Posted by
German_EE
on 17 Dec, 2014 14:37
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Wikipedia says that the War Department / War Office became the Ministry of Defence in 1964, after this unit was manufactured. 'MOD' on the inside plate is therefore to mark MODifications 1-25.
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My first thought when seeing those flatish devices marked 1R is that they were diodes. I would never have thought them to be capacitors. Are you sure Dave?
Agreed. They're IR (International Rectifier) 2E1 diodes.
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#19 Reply
Posted by
RobertoLG
on 17 Dec, 2014 15:36
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#20 Reply
Posted by
w2aew
on 17 Dec, 2014 16:06
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Gee - I hope I look as good as that thing does when I'm that old. Oh wait, I *am* that old! I was born the same year that it was born...
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Yes Dave please fix it,I'd love to see it working.
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#23 Reply
Posted by
PA4TIM
on 17 Dec, 2014 19:05
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CT models are military models/versions. I have a CT38, a huge avo VTVM , CV is also a militairy thing, many tubes have a CV number. I have seen those MOD plates on many english militairy stuff. Like on Murphy's (ao on a 1949 version) and Racals. I do not think it stands for modification.
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#24 Reply
Posted by
fcb
on 17 Dec, 2014 19:45
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Those MOD plates do stand for MODification - they are (or were) very common on gear here in the UK, you often see them with numbers punched out/scratched or ticked indicating which mods have been performed. I've seen brand new gear delivered with a few of these punched out before.