vintage C&H watt-hour meter test set

[djrm]

It was the FARS rally meeting at Sandtoft on Sunday, I look forward to it, there is usually a good selection of interesting electronic gear goar on sale there.  This time was no exception and I came back with HP and Tektronics 100 MHz scopes, a video vector analyzer and waveform monitor and also this old piece of test equipment. As far as I can tell it is for testing three phase watt hour meters, made by an early player if this field - Chamberlin and Hookham of Birmingham. It caught my attention as it seems to have a three phase transformer in it which I thought could be useful or interesting. I've not found anything like it by searching online. I'm tempted to try and get hold of an old watt-hour meter to see if I can exercise it before abandoning it into a cornet of my shed but if anybody knows anything about these I would like to hear about it.
   

My other acquisitions are more interesting, I have a Tektronix 2236 'scope. This one has a built in DVM VFD display to measure input waveform properties and also conventional 4mm jack inputs to use it as a traditional DVM. A precursor to modern scopes with everything displayed on the screen. its mainly working now, I'm waiting for some replacement transistors to fix the vertical display. The HP scope is a 1740A, I cant get the timebase to trigger so a bit more manual reading needed to identify where the problem could lie. The vectorscope and monitor are working, Ive tested them on my colour bar generator - a RIFA cap inside gave up during this test put it hasn't caused any further damage - I'm glad I tested it in the shed though because it smelt awful.

Best regards, David.

[Mike Watterson]

As bad as Selenium "rotted fish". Very distinctive.
I've never seen a Rifa cap across the mains in the last 25 years that hadn't failed badly.

[boater sam]

When you see a Rifa cap, you know that it will always end badly.
Sam.

[Nick]

Rifa were acquired by Kemet probably 20 years ago.  There are plenty of good Rifa caps around, especially their big industrial electrolytics, it's some of their PME 271 series X1/2 and Y1/2 caps that were dodgy.

The epoxy coating would fail over time, letting in moisture - this then resulted in failure with a readily identifiable smell - I had it happen on several bits of Tek & HP kit. They were also used internally in Schaffner encapsulated mains filters which were also commonly used in Tek, HP and many other bits of kit - these encapsulated IEC power inlets were also prone to failure.

[djrm]

Here are a couple of photos showing the vector scope and video analyser being fed from my old Grundig colour bar generator.
   
   
Now to try and understand what they can tell me. I know the basics but have no idea if they are revealing anything of value.
I had a quick demo of the vectorscope down at the BEM on my last visit, never thought I'd end up owning one.
I have another colour bar generator somewhere, much poorer design my Manor Supplies. The colours are not even in the correct order. When I find it I'll make a comparison.

[ppppenguin]

Which model Vectorscope do you have? Incidentally, Vectorscope is strictly speaking a Tektronix trademark but has become generic. It's of little use outside a TV studio or other facility where pictures are being originated. now that PAL and NTSC are obsolete it has much less meaning in a component environment, whether analogue or digital.

Your Grundig generator is giving a fairly nasty waveform. Lots of overshoots and no breezeway. That the gap between the end of sync and start of burst. Some TV mender's generators are much worse!

Perhaps surprisingly the vector display is pretty good. The dots are fairly clean and more or less in the boxes. The lines joining the dots are faint as expected but pretty straight. They can be quite curved or loopy. Though it's easy to blame the generator for errors in the vectorscope. When you're setting up a PAL or NTSC coder the vector display is only a final check. Most of the adjustments are done with a waveform monitor or oscilloscope.

Some vectorscopes have extra functions. My Tek 1755A, the last generation of classic analogue instruments, can measure SCH phase (the phase relationship between subcarrier and H sync) which is difficult to do. It's critical for editing on broadcast grade analogue analogue VTRs. It's also difficult to measure without a specialist instrument. It can also strobe out individual lines from anywhere in the 8 field PAL sequence.

[djrm]

Hi Jeffrey, Thanks for the display interpretation, very much appreciated. I have also found some manuals online which has helped.

This is the thing I bought, it consists of a Tektronix 1711B and 1721 bolted together as a single 19 inch unit. There were a couple on sale, I thought I had picked the better looking of the two, it had the line selection feature but I found when I tried it that I must have accidentally picked up the wrong unit.
   

Here is another oddity I came away with. its paper backed recording tape. I'll try playing it when I get my ferrograph out.
   
Best regards, David.

[ppppenguin]

The 1711 and 1721 are the most basic of the Tek 1700 series video instruments. We may have spare copies of the manuals if you need them .