Anyone recognise this ancient CRO?

[Phil Allison]

"Bob Parker"
Phil Allison wrote:

BTW:

Did you know that Norm Edge drove a tank in WW2 ?

Sounds like you got to know the people behind the counter better than I
did.

** Went there several times a week from 1973 till the finish of business in
the late 80s. I even worked behind the counter for one day in 1973 and
topped the sales list - Julie did the adding up at the end of each day and
came over to tell me personally. There and then, Norm offered me a permanent
job and was quite forceful about it. Since I was working for his son Bill at
the time (Edge Electrix) I foolishly declined.

I remember Norm Edge well but I never knew he was a tank driver(!).

** I recall the conversation, Norm had added my invoice ( plus 27.5% sales
tax ) and it came to $19.44.

Me: " 1944, ah that was a good year " .

Norm: " Don't say that - 1944 was a terrible year !!

I was in the Army driving bloody tanks back then ".

The weird thing is that I think I still remember both of RDS's phone
numbers: 211-0191 and 211-0816. Was that them?

** Sorry, chucked all my yellow invoices decades ago.



.... Phil

 

[Chas]

"Bob Parker" <"bobp[deletethis]"@bluebottle.com> wrote in message
news:ZZudnV2EVLX9pEvMnZ2dnUVZ_uKdnZ2d@westnet.com.au...

A bloke's contacted me in the hope that I might know something about a
simple oscilloscope his late father built many years ago. It's got a 2" RCA
CRT and only four (octal) valves.

I've uploaded the photo he sent me, to
http://members.ozemail.com.au/~bobpar/CRO.JPG

One of the visible valves looks like it could be a 5Y3G and another a
6J7G. A lot of the visible capacitors look like those yellow Philips
polyester(?) ones from the 1960s but his father quite likely replaced
original waxed papers caps with them.

Does anyone recognise it?



Cheers,
Bob

That scope looks like the one described in the March 1950 edition of Radio &
Hobbies. It was designed by the late Derrick Williamson, with whom I had
the privelidge to know as a friend, colleague and mentor. A revised version
with a linear "hard" timebase was published the following month. The four
octal valves is slightly at odds with the original, which had a 6SJ7 to
drive each set of deflection plates, an 884 for the timebase, and a 6X5 for
the HT rectifier. An 80 supplied the EHT, making five valves. Perhaps one
of the valves is missing or not visible in the photo?
--
Regards,

Chas.

(To email me, replace "xxx" with letters tango papa golf.)

 

[Bob Parker]

On 9/07/2013 20:16 Chas wrote:

"@bluebottle.com> wrote in message
news:ZZudnV2EVLX9pEvMnZ2dnUVZ_uKdnZ2d@westnet.com.au...
A bloke's contacted me in the hope that I might know something about a
simple oscilloscope his late father built many years ago. It's got a 2" RCA
CRT and only four (octal) valves.

I've uploaded the photo he sent me, to
http://members.ozemail.com.au/~bobpar/CRO.JPG

One of the visible valves looks like it could be a 5Y3G and another a
6J7G. A lot of the visible capacitors look like those yellow Philips
polyester(?) ones from the 1960s but his father quite likely replaced
original waxed papers caps with them.

Does anyone recognise it?



Cheers,
Bob

That scope looks like the one described in the March 1950 edition of Radio &
Hobbies. It was designed by the late Derrick Williamson, with whom I had
the privelidge to know as a friend, colleague and mentor. A revised version
with a linear "hard" timebase was published the following month. The four
octal valves is slightly at odds with the original, which had a 6SJ7 to
drive each set of deflection plates, an 884 for the timebase, and a 6X5 for
the HT rectifier. An 80 supplied the EHT, making five valves. Perhaps one
of the valves is missing or not visible in the photo?

There's a much more comprehensive set of photos in my online photo album
now, at http://tinyurl.com/2inchcro

The valves have been identified as 2x 6J7G, 1x 80, 1x 884, 1x 902 (CRT).
It looks as though the builder of this instrument could have adapted the
design of the 1938 RCA 151-2 Oscillograph to use locally-available
parts. You can see it at
http://www.myvintagetv.com/vintage_test_equipment.htm a bit down from
the top of the page.

 

[yaputya]

"Bob Parker" <"bobp[deletethis]"@bluebottle.com> wrote in message newsidnZfLM7lHnEfMnZ2dnUVZ_h-dnZ2d@westnet.com.au...

On 7/07/2013 18:43 Phil Allison wrote:
"Bob Parker"
Phil Allison wrote:


** Not the same one - I built the simpler May '66 version, with 2MHz
bandwidth.

More compact, case less than half the size (5 x 7.5 x 8.5 inch) and used
only 5 valves:

1x12AT7 Schmitt trigger, 2x6BL8 for horizontal sweep and 2x6GH8 for the
vertical amp.

The shift, focus and astig pots were moved to the rear.

The 1S/cm time was left out as was DC coupling, illuminated graticule,
filter choke and brightness pot.

But the Mu-Metal CRT shield was kept and it uses a custom Ferguson tranny
( with copper strap) for all voltages.

The overall DC voltage on the CRT was increased to 650V, making the trace
quite bright and sharp.

I still have it and it still works with the original CRT.

It even got a recent up-grade with a BNC socket on the front !


Still quite a respectable instrument. The BNC socket makes it a hell of
a lot easier to connect a real probe to it.


** Others have mentioned seeing green CRTs used to make home brew TVs in the
B&W days.

Well, soon as I got my new CRO working, I hooked up the vertical, horizontal
and Z inputs to the vertical, horizontal and video circuits of a HMV 17
inch, console TV set.

Got a tiny green pic and my choice of negative or positive images - cool.

Current generation geeks have no idea ....



.... Phil


I tried doing the same thing in the early 1970s with a brand-name oscilloscope back in the PMG.

My own TV back then was an Astor 17", model ESJ if I remember correctly. I remember buying a new vertical output transformer for
it from Radio Despatch Service.... Geoff Wood served me.


Bob

I assume you mean RDS on Broadway near Harris St.
The pub on the corner (Agincourt) had a nice curry restaurant called
The Sri Lanka Room, I often had lunch there after going to RDS.