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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders. |
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10th Apr 2018, 2:38 pm | #1 |
Hexode
Join Date: Mar 2008
Location: Manchester, UK.
Posts: 478
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Cossor 339A Scope
Oh dear.. let's not talk about how I obtained this one.
A rusty Cossor 339A, complete (but missing the grid plate on the front) I haven't taken it out fully yet, the wing nuts are stopping the chassis from being taken out completely. It will need a complete brush and vacuum soon. It's now being stored in a dry place until I finish with the pet and the beeb master. My thoughts are either restore it or convert it into a scope clock (that if the CRT is in good condition) Your thoughts on this? Here are some photos anyway.
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10th Apr 2018, 4:06 pm | #2 |
Moderator
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 6,863
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Re: Cossor 339A Scope
Wow! I don't think I have seen one that rusty before
I suppose as it will need extensive restoration a clock is as good a use as any I can think of. It will double up as a room heater in the winter Cheers Mike T
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Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk |
10th Apr 2018, 6:00 pm | #3 |
Octode
Join Date: Nov 2011
Location: Manchester, UK.
Posts: 1,874
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Re: Cossor 339A Scope
I have two Thurlby DSA 524 Digital Storage Adaptors to sell as part of my (seemingly permanent) charity sell-up - thread here:
https://www.vintage-radio.net/forum/...d.php?t=142128 If your scope will do dc coupled 100mV / y.div, 50us / x.div, then you could couple one of them to it and turn it into a rather improbable dual-beam digital storage scope |
10th Apr 2018, 6:02 pm | #4 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,932
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Re: Cossor 339A Scope
I would attempt to restore as intended,a scope.I have one of these and the crt is fine.
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10th Apr 2018, 7:32 pm | #5 |
Hexode
Join Date: Apr 2012
Location: Chorley, Lancashire, UK.
Posts: 260
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Re: Cossor 339A Scope
Rebuild it! I have re-built 2 .... I was inspired by David Simpson's account https://www.vintage-radio.net/forum/...ad.php?t=53357 . At the end of this thread you can see my re-builds. I am just up the road from you and can probably find the spares that you need including the missing plate. I also have a spare chassis that has been shot blasted and sprayed - it looks good but you will have to ensure that you run some extra earth wires where connections went direct to chassis ... I did this on one of my re-builds and it works fine. Having a spare chassis greatly simplifies the build as one can transfer components/wiring directly across without having to do a complete dismantle.
Mark |
10th Apr 2018, 9:16 pm | #6 |
Nonode
Join Date: Mar 2008
Location: Aberdeen, UK.
Posts: 2,852
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Re: Cossor 339A Scope
Thanks for the nice reference Mark.
My main worry would be the state of the thumping great Transformer. One of the sec windings is the source of the 1200V EHT. It'll need careful drying out & every winding measured & meggered. If the T/F is phooked, then its pointless considering renovation or restoration. Also, the rust looks jolly extensive. Best bet would be to carefully remove the CRT & ask Mark to kindly test it by substitution. Whilst you carefully disconnect & remove the T/F & test it. All my Cossor 339 sets & documentation is now with Mark, which I guess makes him the one & only 339 expert UK enthusiast. The 339 was the main Oscillograph used in wartime projects & it would be great to see another fully restored. Regards, David |
10th Apr 2018, 9:45 pm | #7 |
Moderator
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 6,863
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Re: Cossor 339A Scope
OMG does that mean I have to restore the three I have
I am a Cossor fan but if I have to retore everything I need another 100 years Cheers Mike T
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Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk |
10th Apr 2018, 11:41 pm | #8 |
Dekatron
Join Date: Apr 2005
Location: Bewdley, Worcestershire, UK.
Posts: 4,748
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Re: Cossor 339A Scope
I have a soft spot for Cossor 339s, having partially restored one and repaired another. Apart from the historic interest, they aren't really a fat lot of use nowadays; the timebase and Y-amps aren't calibrated, the bandwidth is only 1 or 2 MHz if you're lucky, and they weigh a ton. David's warning about the transformer is very pertinent, too; I received a 1200V belt off mine and it was very painful, albeit via a leakage path so not fatal, but please beware.
I still have a brand new spare tube and Mu-metal shield here if you (or anyone else) wants it. No idea of colour or beams though. From memory, all the resistors in my unit were fine but I had to replace virtually all the waxies.
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11th Apr 2018, 8:29 am | #9 |
Nonode
Join Date: May 2007
Location: Preston, Lancashire, UK.
Posts: 2,511
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Re: Cossor 339A Scope
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11th Apr 2018, 10:23 am | #10 |
Nonode
Join Date: Mar 2008
Location: Aberdeen, UK.
Posts: 2,852
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Re: Cossor 339A Scope
Just one apiece, Mike & Andy. Think of the buzz you'll get(not from 1200V I hope), when you see those 807's glowing happily away. As Phil says, there are, I think 4 different CRT's. A single beam option & three double beam with different colours of phosphorescence & persistence. The 3339 & the 339's were not just a general purpose 'scope. What makes them special was their use in waveform photography. My only regret was never to acquire the special camera attachment.
Regards, David |
11th Apr 2018, 10:41 am | #11 |
Dekatron
Join Date: Apr 2005
Location: Bewdley, Worcestershire, UK.
Posts: 4,748
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Re: Cossor 339A Scope
David coined the wonderfully descriptive term "Harpic blue" for one of the colours, and it's bang-on!
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Phil Optimist [n]: One who is not in possession of the full facts |
11th Apr 2018, 10:46 am | #12 |
Hexode
Join Date: Mar 2008
Location: Manchester, UK.
Posts: 478
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Re: Cossor 339A Scope
What a great response. I am inspired by David's restoration, thats great!
I think I will strip everything down, clean up the chassis then rebuild it. But in addition to this, add in a scope clock (without spoiling the appearance). Mark I will be in touch soon as I get all the other project sorted out.
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11th Apr 2018, 11:24 am | #13 |
Nonode
Join Date: May 2007
Location: Preston, Lancashire, UK.
Posts: 2,511
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Re: Cossor 339A Scope
Although very primitive by today's standards, I think it was a very capable general purpose 'scope in its day. My manual is dated 1942, so it must have been introduced around then. It was adopted by the Air Ministry as their Oscilloscope Type 10, which is why I ended up with a second example, I couldn't resist the AM stamped label!
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