Author Topic: EEVblog #693 - AVO Transistor Analyser Teardown (Read 20979 times)

EEVblog · « **on:** December 17, 2014, 03:11:57 am »

Dave tears down a 1962 vintage AVO Transistor Analyser.

The auction score video:

SeanB · « **Reply #1 on:** December 17, 2014, 04:24:12 am »

I have the baby brother of that one, it fits in the box in the middle.

ratdude747 · « **Reply #2 on:** December 17, 2014, 06:50:03 am »

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.

Lightages · « **Reply #3 on:** December 17, 2014, 07:05:00 am »

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?

digital · « **Reply #4 on:** December 17, 2014, 08:22:02 am »

Dave please replace that condenser and do a video of the tester working I am sure a lot of others would enjoy it.Regards

G7PSK · « **Reply #5 on:** December 17, 2014, 09:05:15 am »

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have the habit of storing equipment just in case they have a war and then after forty years or so realise that it is out of date, I have had a few bits of kit unused ex military.

German_EE · « **Reply #6 on:** December 17, 2014, 09:29:52 am »

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

jipihorn · « **Reply #7 on:** December 17, 2014, 10:08:21 am »

"Love a good set of balls"

Brilliant.

J.

nathanpc · « **Reply #8 on:** December 17, 2014, 10:45:44 am »

I would love to see a video of you replacing those old ~~capacitors~~ condensers and playing around with it analyzing some transistors.

fcb · « **Reply #9 on:** December 17, 2014, 11:33:21 am »

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.

JackOfVA · « **Reply #10 on:** December 17, 2014, 12:25:54 pm »

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.

R_Gtx · « **Reply #11 on:** December 17, 2014, 01:08:39 pm »

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.

c4757p · « **Reply #12 on:** December 17, 2014, 01:20:33 pm »

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?

Macbeth · « **Reply #13 on:** December 17, 2014, 01:25:36 pm »

Quote from: Lightages on December 17, 2014, 07:05:00 am

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...

Refrigerator · « **Reply #14 on:** December 17, 2014, 01:32:19 pm »

Imo a C cell battery would fit perfecly in those battery cans .

c4757p · « **Reply #15 on:** December 17, 2014, 01:33:51 pm »

Quote from: Refrigerator on December 17, 2014, 01:32:19 pm

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.

Quote from: Macbeth on December 17, 2014, 01:25:36 pm

Quote from: Lightages on December 17, 2014, 07:05:00 am
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.

Macbeth · « **Reply #16 on:** December 17, 2014, 01:34:13 pm »

Quote from: German_EE on December 17, 2014, 09:29:52 am

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.

German_EE · « **Reply #17 on:** December 17, 2014, 02:37:45 pm »

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.

Andy Watson · « **Reply #18 on:** December 17, 2014, 02:57:59 pm »

Quote from: Lightages on December 17, 2014, 07:05:00 am

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.

RobertoLG · « **Reply #19 on:** December 17, 2014, 03:36:39 pm »

Dave here are some battery adapters, maybe you are interested for future use, dunno anyways here is the link

http://www.amazon.com/C-sized-Adapter-Shells-AA-Battery/dp/B000855034

w2aew · « **Reply #20 on:** December 17, 2014, 04:06:09 pm »

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...

Dave Turner · « **Reply #21 on:** December 17, 2014, 04:59:35 pm »

According to http://www.vintage-radio.net/forum/showthread.php?t=78716
the 1289 4.5v cycle battery would yield 3 U10 sized cells. I've not tried it myself but may be worth checking out.

Electronics-Repairman · « **Reply #22 on:** December 17, 2014, 05:32:06 pm »

Yes Dave please fix it,I'd love to see it working.

PA4TIM · « **Reply #23 on:** December 17, 2014, 07:05:47 pm »

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.

fcb · « **Reply #24 on:** December 17, 2014, 07:45:53 pm »

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.


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